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To evaluate the effects of including extra alfalfa hay (AH) in high-concentrate diets fed to beef heifers on intake, ADG, G:F, and carcass and meat quality, we used 24 Simmental heifers (initial BW 235.6 ± 4.19 kg). Heifers were blocked in four BW blocks and allotted in groups of 3 in a randomized block design with 2 treatments and 12 heifers per treatment. Treatment diets offered as total mixed ration (TMR) were (i) TMR with 10% barley straw (BS), considered the control diet, and (ii) TMR with 19% AH. The experiment was performed over four 28-d experimental periods, and we took measurements in the last week of each period. After this period of performance control, heifers were fed the corresponding diet until each BW block reached the target weight of 400 kg on average. Feed intake and ADG were greater for AH than BS (9.5 vs. 8.4 kg/d, and 1.45 vs. 1.29 kg/d, respectively; P < 0.05), but G:F was unaffected by diet (P > 0.10). Diet did not affect HCW, dressing percentage, backfat color, pH and meat color, or carcass grade. The sixth rib was dissected to determine the proportion of fat, lean, and bone, which were unaffected by diet. Diet did not affect the LM composition in water, protein, collagen, intramuscular fat, and cholesterol. The intramuscular fat proportion of C18:1 n -7 was greater in BS than in AH (P = 0.016), whereas the proportion of C18:3 n -3 tended to be greater in AH than in BS (P = 0.09). When fatty acid concentration was expressed as gram per 100 g of LM, these differences disappeared, and only the content of C15:0 tended to be greater (P = 0.08) in BS than in AH. Meat characteristics evaluated by trained panelists did not differ in toughness, chewiness, juiciness, odor, taste, and overall acceptability, and there were no differences between diets in Warner–Bratzler shear force values after 3 or 10 d of aging (P > 0.10). In summary, heifers fed TMR with AH at 19% of inclusion showed a greater feed intake and ADG than those fed BS at 10% of inclusion, but without affecting G:F ratio. However, this extra AH was not sufficient to cause any relevant change in the carcass and meat quality of the heifers fed this diet. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effects of different forms of hydrolyzable tannin [ HT ; source (chestnut, CN ; tannic acid, TA); subunit (gallic acid, GA)] on apparent total-tract digestibility, methane (CH 4 ) production, and nitrogen (N) utilization in beef cattle fed an alfalfa silage-based diet. Eight ruminally cannulated heifers with an initial BW of 480 ± 29.2 kg (mean ± SD) were used in a double 4 × 4 Latin square experiment. The experiment consisted of four 28-d periods (14-d adaptation, 14-d measurements) and a 7-d washout between periods. The animals received a basal diet with 19.8% CP (DM basis) content containing 75% alfalfa silage, 20% barley silage, and 5% supplement (DM basis) with or without different forms of HT. The dietary treatments were as follows: control (no HT), GA (1.5% of diet DM), TA (1.5% of diet DM), and CN (2% of diet DM). Animals were fed 95% of their ad libitum intake during the measurement phase. Total fecal excretion was collected for 4 d, CH4 was measured for 72 h using respiration chambers, and ruminal fermentation variables and plasma urea N (PUN) concentration were measured on 2 nonconsecutive days before and after feeding. The restricted DM (DMI; 10.79 ± 1.076 kg/d) and nutrient intakes did not differ (P ≥ 0.22) among treatments. Furthermore, apparent DM digestibility (60.3 ± 0.86%) was not affected (P = 0.20) by treatment, but CP digestibility decreased for TA and CN compared with control and GA treatments (63.1 vs. 69.0%; P < 0.001). Total VFA concentration tended (P = 0.089) to increase for GA compared with control and TA (134 vs. 125 and 126 mM) and intermediate for CN (129 mM). The PUN concentration was lower for all HT treatments compared with control (196 vs. 213 mg/L; P = 0.02). Both TA and CN increased the proportion of N excreted in feces and decreased the proportion in urine compared with control and GA (43.9% vs. 37.8% and 56.1% vs. 62.2%; respectively; P < 0.001). However, the proportion of urea N in urinary N decreased for all HT treatments compared with control (47.2% vs. 51.2%; P = 0.02). Also, GA tended to decrease CH4/DMI (20.4 vs. 22.3 g/kg DMI; P = 0.07) and decreased the proportion of GE intake emitted as CH4 (5.16 vs. 5.71%; P = 0.04) compared with control. Thus, among the different forms of HT applied to a high-protein alfalfa silage-based diet, both TA and CN had no effect on CH4 production, but decreased CP digestibility and shifted N excretion from urine to feces, whereas GA (i.e. HT subunit) decreased CH4 production and decreased the proportion of urea N in urinary N in beef cattle without affecting CP digestibility. Thus, feeding the HT subunit, GA, has the potential to decrease environment impact of ruminants (lower CH4 and ammonia emissions), without decreasing animal performance. [ABSTRACT FROM AUTHOR]

Highlights • Increasing feed efficiency in livestock is seen as a way to improve farm sustainability. • The role of social dominance and activity in efficiency was assessed in beef steers. • Dominance affected feed intake, but did not directly affect efficiency. • A more consistent length of feeding bout was associated with efficiency. • Reducing feeding competition may allow all animals to express full growth potential. Abstract To increase the profitability and sustainability of beef production systems, the use of animals with high feed efficiency is preferred. Efficient animals eat less than their peers for the same or better growth. This efficiency can be measured using feed conversion ratios (FCR) and residual feed intake (RFI) parameters. However, the biological mechanisms, particularly those related to the animal's behaviour and personality, are poorly understood. An individual animal's behaviour, such as its activity levels, may contribute to efficiency. Feed intake is also a factor in efficiency, and therefore, social dominance rank may also indirectly affect efficiency through its influence on feeding behaviour. This experiment investigated the effects of dominance on feeding behaviour, as well as of dominance and activity on average daily gain (ADG), FCR and RFI in two breeds of beef cattle. The study used a 2 × 2 design with 80 cattle of two breed-types (Charolais-cross (CHx) (n = 41) and Luing (n = 39)) and two diets (a concentrate-based diet (CONC) and a mixed forage and concentrate diet (MIXED)). For each individual steer, FCR and RFI were measured over a 56-day performance test. Feed intake, patterns of feeding behaviour, activity and dominance were also measured. Feed intake was affected by dominance, with more dominant steers having significantly higher dry matter intakes (P = 0.001) and feeding rates (P = 0.006) suggesting that dominant animals had priority of access to the feeders. Steers with higher ADG had higher intakes and performed more standing bouts. Steers with better FCR values performed more standing bouts and younger animals had better FCR. For RFI there was also an interaction between breed and variation in length of the feeding events, showing that Luing steers with more consistent feed bout lengths had better RFI, with no association shown for CHx steers. There was no direct effect of dominance on ADG, FCR or RFI. However, the effect of dominance on feed intake suggests that measures of performance in any study may be affected by feeder-space allocation. The associations between standing bouts and feeding bouts with efficiency measures also suggest that individual animal behavioural characteristics influence efficiency and that overall efficiency of all animals may be improved by allowing animals to express individual patterns of behaviour. [ABSTRACT FROM AUTHOR]

Genetic and phenotypic parameters for feed efficiency, growth, and carcass traits for Australian Angus beef cattle were estimated. Growth traits included birth weight (BWT), 200-d weight (200dWT), 400-d weight (400dWT), and 600-d weight (600dWT). Traits associated with feed efficiency were average daily weight gain (ADG), metabolic midweight, average of daily feed intake (FI), feed conversion ratio (FCR), residual feed intake (RFI), and residual gain (RG). Carcass traits involved were carcass eye muscle area (CEMA), carcass intramuscular fat (IMF), subcutaneous fat depths at the 12th/13th rib (CRIB), rump P8 fat depth (P8FAT), and carcass weight (CWT). For growth traits, heritability estimates ranged from 0.14 ± 0.03 for 200dWT to 0.48 ± 0.06 for 600dWT. For feed efficiency traits, direct heritability estimates for FI, FCR, RFI, and RG were 0.55 ± 0.08, 0.20 ± 0.06, 0.40 ± 0.07, and 0.19 ± 0.06, respectively. High heritability estimates were observed for CEMA, IMF, P8FAT, and CWT of 0.52 ± 0.09, 0.61 ± 0.09, 0.55 ± 0.09, and 0.66 ± 0.09, respectively. Strong positive genetic correlations were found for FI with 200dWT, 400dWT, and 600dWT of 0.68 ± 0.09, 0.42 ± 0.11, and 0.61 ± 0.07, respectively. Weak genetic correlations were observed between RFI and growth traits. For carcass traits, genetic correlations between RFI and CEMA, IMF, CRIB, P8FAT, CWT were −0.19 ± 0.14, 0.31 ± 0.14, 0.18 ± 0.16, 0.24 ± 0.13, and 0.40 ± 0.12, respectively. There was a tendency for low to moderate unfavorable genetic associations between feed efficiency traits, evaluated as RFI and RG, with growth and carcass traits. This implies that selection for RFI would have slight negative impacts on growth and reduce carcass quality. To avoid this, it would be necessary to build selection indices to select feed efficient animals without compromising growth and meat quality. [ABSTRACT FROM AUTHOR]

In this study the determination of micro mineral elements (selenium, iron and zinc) in meat, spleen and liver of beef were carried out. Brahman cross steers reared under intensive production system in feedlot for 87 days. Samples of meat, spleen and liver were collected from 16 steers aged 24-36 months with four types of feeding treatment, feeding without Se (group I) and feeding with additional supplementary of 0.3 ppm selenium for 25, 50 and 75 days (group II, III and IV, respectively). Samples characterization were carried out by instrumental neutron activation analysis (INAA) using irradiation facility in G.A Siwabessy Serpong reactor. Analysis results showed that there is an increasing of selenium content in meat and liver after 75 days feeding. The mean of selenium in liver for group I, II, III and IV were 0.13, 0.17, 0.20 and 0.31 mg/kg wet weight, respectively, while for liver were 0.43, 0.53, 0.60 and 0.70 mg/kg wet weight, respectively. The mean concentrations for iron in meat, spleen and liver were 11.85, 139, and 38.94 mg/kg, respectively, for zinc were 27.90, 21.70 and 25.27 mg/kg, respectively. In this study, the meat and liver contribute more than 100% of recommended daily allowance (RDA) of Se for children and adults. Spleen have contribution of RDA of Fe 53 to 154%, while the RDA of Zn is contributed mostly from meat by 21 to 56%. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that supplementation with three protein levels improves fermentation parameters without changing the rumen microbial population of grazing beef cattle in the rainy season. Four rumen-cannulated Nellore bulls (432 ± 21 kg of body weight) were used in a 4 × 4 Latin square design with four supplements and four experimental periods of 21 days each. The treatments were mineral supplement (ad libitum) and supplements with low, medium (MPS), and high protein supplement (HPS), supplying 106, 408, and 601 g/day of CP, respectively. The abundance of each target taxon was calculated as a fraction of the total 16S rRNA gene copies in the samples, using taxon-specific and domain bacteria primers. Supplemented animals showed lower (P < 0.05) proportions of Ruminococcus flavefaciens and greater (P < 0.05) proportions of Ruminococcus albus and Butyrivibrio fibrisolvens than animals that received only the mineral supplement. The HPS supplement resulted in higher (P < 0.05) proportions of Fibrobacter succinogenes, R. flavefaciens, and B. fibrisolvens and lower (P < 0.05) proportions of R. albus than the MPS supplement. Based on our results, high protein supplementation improves the ruminal conditions and facilitates the growth of cellulolytic bacteria in the rumen of bulls on pastures during the rainy season. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to evaluate the effects of crude glycerin (CG) and virginiamycin (VM) diets on ruminal fermentation and microbial population of feedlot Nellore cattle. Eight rumen fistulated bulls (BW = 600 ± 34 kg; 26 ± 3 months) were used in a replicated 4 × 4 Latin square (21-d periods) with 2 × 2 factorial arrangement of treatments: diets without virginiamycin (VM−) or virginiamycin at 25 mg/kg DM (VM+) combined with diets without crude glycerin (CG−) or CG (80% glycerol) at 100 g/kg DM (CG+). The sugar cane bagasse was used as the exclusive roughage in the proportion of 200 g/kg in dry matter of diet and crude glycerin replaced corn in the diet formulation. Ruminal samples were collected immediately before feeding and at 3, 6, 12 and 18 h post feeding on days 20 and 21 of the sampling week. Data were analyzed in a replicated 4 × 4 Latin square with a 2 × 2 factorial using the MIXED procedure of SAS (SAS Inst., Inc., Cary, NC). There were no CG × VM interactions for any variable measured ( P ≥  0.10). The intake of DM had a tendency to be greater in CG+ than CG− diets ( P =  0.07). Apparent total tract digestibilities of nutrients were similar among diets ( P ≥  0.10). Diets with CG or VM had similar values of pH (mean = 6.15; P ≥  0.10). Data showed that CG or VM did not affect the concentration of total VFA (116.92 mM; P ≥  0.10). The proportion of propionate increased 27.5% in CG+ diets, regardless of VM inclusion ( P =  0.01). Acetate:propionate ratio was lower in CG+ compared to CG− diets (3.58 vs. 2.12; P ≥  0.10). Valerate and butyrate proportion was greater in CG+ than CG− diets ( P <  0.05). The inclusion of VM or CG did not alter the relative abundance of fibrolityc bacteria (P ≥ 0.10). Total protozoa counts ( P =  0.052) and Metadinium spp. ( P =  0.058) had a tendency to decrease in VM+ than VM− diets ( P <  0.10). Crude glycerin had positive effects on rumen fermentation products and can replace virginiamycin with increment of Megasphaera elsdenii abundance. However, combining virginiamycin and glycerin does not affect positively rumen fermentation and growth of bacteria that metabolize lactate. [ABSTRACT FROM AUTHOR]

Because enteric methane (CH4) production from ruminants represents a source of greenhouse gas emissions and an energy loss for the host animal alternatives to minimize emissions is a current research priority. Seven 37-d trials tested the effect of encapsulated nitrate (EN) and sodium monensin (MON) in diets commonly fed to dairy (DAIRY; 50:50 forage to concentrate; four trials) and beef cattle (BEEF; 15:85 forage to concentrate; three trials) on rumen fermentation and CH4 production using a semi-continuous fermentation system. A 3 × 2 factorial arrangement was used and additives (0, 1.25, and 2.5% of EN; 0 and 4 mg/L of MON) were tested alone and combined (EN + MON) totaling six treatments. Rumen fluid was pooled from five nonadapted lactating cows fed 50:50 forage to concentrate diet 3 h after morning feeding, and 1 L of processed inoculum was transferred to 2.2-L vessels. Treatment diets were added to nylon bags which remained in the anaerobic fermentation of mixed rumen microorganisms for 48 h. Nitrate decreased CH4 production in DAIRY (24.7 vs. 32.1 mM/d; P < 0.01) and BEEF trials (33.5 vs. 43.5 mM/d; P < 0.01). Methane production was decreased by MON in DAIRY (26.3 vs. 32.1; P < 0.01) and BEEF (26.6 vs. 43.5 mM/d; P < 0.01). The combination of EN + MON further decreased CH4 in DAIRY (21.3 vs. 32.1 mM/d; P = 0.03) and BEEF (19.3 vs. 43.5 mM/d; P = 0.01). Nitrate did not affect major VFA production in DAIRY and BEEF trials, but significantly decreased digestion of protein (96.8 vs. 97.6%; P < 0.01) and starch (79.0 vs. 80.4%; P < 0.01) in DAIRY and NDF (29.3 vs. 32.5%; P < 0.01) and starch (88.5 vs. 90.3%; P < 0.01) in BEEF. Monensin significantly affected VFA pattern with an increase in propionate (P < 0.01) and a decrease on acetate (P < 0.01) production with consequent decrease on acetate-to-propionate ratio in DAIRY (1.6 vs. 2.0; P < 0.01) and BEEF (1.6 vs. 1.9; P < 0.01). Monensin decreased NDF digestion in BEEF only (29.3 vs. 32.5%; P < 0.01). Significant concentrations of nitrate and nitrite were detected only for EN and EN + MON (P < 0.01). Nitrate and MON effectively decreased CH4 production when fed separately and the combination of additives additively decreased CH4 production. [ABSTRACT FROM AUTHOR]

Heterotrophic production of microalgae biomass provides a consistent, high-quality source of docosahexaenoic acid (DHA; C22:6 n-3) in triglyceride oils that could be used as a ration supplement for feedlot steers to improve nutritional qualities of beef. Sixty Angus × Simmental steers (438 ± 6.4 kg) were allotted to two treatments (30 steers each, six pens, five steers/pen) to determine the effects of ForPLUS (DHA-rich microalgae Aurantiochytrium limacinum; 63.6% fat; 17.9% DHA; 30 mg/kg Sel-Plex; Alltech Inc.) on performance, insulin sensitivity, LM fatty acid composition, and meat quality. Steers were fed basal diets containing 45% corn, 30% distillers dried grains with solubles, 20% corn silage, and 5% supplement. Basal diets were formulated to contain 16.1% CP and 1.32 Mcal/kg NEg. Treatments were delivered to steers in a ground corn-based top-dress (454 g total/steer) and contained no microalgae for control steers or 100 g/steer daily of ForPLUS for microalgae steers. A glucose tolerance test (GTT) was performed 10 d prior to slaughter. Steers were slaughtered when a target pen BW of 621 kg was achieved. Fatty acid oxidation potential was determined by measuring thiobarbituric acid reactive substances (TBARS) on LM samples collected 24 h after slaughter and aged for 48 h or 21 d. Weight and BW gain did not differ during the study (P = 0.13); however, steers fed microalgae remained in the feedlot seven more days compared to steers fed the control diet (111 vs. 104 d; P = 0.04). Overall DMI decreased (P = 0.002) and G:F increased during the second half of the study (P = 0.04) in steers fed microalgae compared to steers fed the control diet. Steers fed microalgae secreted less insulin (P = 0.01) and took longer to clear glucose (P = 0.01) during a 2-h GTT. Carcass traits did not differ between treatments (P = 0.23). Microalgae had no effect on n-6 content (P = 0.67), but more than doubled the n-3 fatty acid percentage and the n-3:n-6 ratio of the LM (P < 0.0001). The percentage of n-3 fatty acids C20:5 and C22:6 were increased (P < 0.0001) 4-fold and 6.25-fold, respectively, by microalgae supplementation. Concentration of TBARS did not differ in LM aged for 48 h (P = 0.91); however, when aged for 21 d, steers fed microalgae tended to produce LM with greater TBARS concentration compared to steers fed the control diet (P = 0.08). In conclusion, DHA-rich microalgae decreased DMI of steers, and increased n-3 fatty acids and beef oxidation in steaks aged for 21 d. [ABSTRACT FROM AUTHOR]

Hereford and Charolais beef cows (n = 24 per breed) were used to study the effect of breed and to evaluate late-cut reed canarygrass (RC) and whole-crop oats plus urea (WCO) compared with late-cut timothy (TG) with respect to feed intake and digestibility, rumination time, fecal particle size (PS) distribution, N excretion, and ruminal microbial CP production (MCP). The TG and RC were cut at flowering and WCO at hard dough stage of maturity. Cows were grouphoused, 6 groups per breed, and fed 3 diets ad libitum in 3 periods. The study was designed as two 3 × 3 Latin squares amalgamated to form a 3 × 6 rectangle for each breed. All data were statistically analyzed on group level. Indigestible NDF (iNDF) and urinary creatinine excretion were used as markers to estimate apparent diet digestibility and daily urine volume, respectively. Fecal PS distribution was determined by dry sieving, and ruminal MCP synthesis was estimated based on urinary output of purine derivatives. The TG diet had a higher apparent digestibility of OM and NDF (P < 0.001) than RC and WCO, which did not differ. The TG diet resulted in the greatest daily DMI, followed by WCO and RC (P < 0.001). Intake of NDF (NDFI, kg/d and % of BW) was greatest for TG, followed by RC and WCO (P < 0.001). Rumination time per kg DMI was longest for RC (P < 0.001), and RC and WCO resulted in longest rumination time per kg NDFI (P < 0.001). The WCO diet resulted in the largest geometric mean fecal PS and proportion of large particles and in the smallest proportion of small particles, whereas the opposite was found for RC, with TG being intermediate (P < 0.001). Intakes in kg per day were higher for Charolais than for Hereford (P = 0.002), but no breed effect was detected when intake was expressed in relation to BW. Charolais ruminated longer per kg NDFI corrected for BW (P = 0.02) and had smaller mean fecal PS (P = 0.049) than Hereford. Total N excretion was highest for RC and lowest for WCO (P < 0.001). The TG diet stimulated MCP production to a greater extent than RC and WCO (P < 0.001). The results indicate that late-cut RC and WCO could be suitable alternatives to late-cut TG for ad libitum feeding of early pregnant beef cows, and that intake was associated with cow BW, but not with breed. The variations in NDF and iNDF concentrations between forage diets were reflected in their effects on intake, rumination, apparent digestibility, and fecal PS. [ABSTRACT FROM AUTHOR]

Fourteen Nellore and 14 Angus young bulls with BW of 381 ± 11.8 kg were randomly assigned into 2 feeding groups (whole shelled corn without forage (WSC) or corn silage and ground corn (GC)) to evaluate chemical composition and expression of genes involved in lipid metabolism in the longissimus thoracis (LT). We hypothesized that bulls fed the WSC diet have greater amounts of intramuscular fat and Angus have higher expression levels of PPAR and SREBF . Meat from Angus bulls had greater ether extract compared to Nellore ( P < 0.05). Muscle from bulls fed the WSC diet had greater expression of PPARA ( P < 0.05) and lower levels of SREBF1 expression ( P < 0.01). The LT of Nellore fed GC had greater expression of FABP4 , ACACA and SCD genes ( P < 0.01). In conclusion, the greater concentration of starch in the WSC diet did not increase marbling in the beef of bulls fed this diet due to the reduced expression of SREBF1 . [ABSTRACT FROM AUTHOR]

In Kenya, most of the livestock are reared on grass using extensive pastoral systems. Nevertheless, intensive feed-lot systems to finish beef cattle have become popular among local producers. The two systems are likely to have a different impact on the eating quality of beef, because quality is determined by the combined effects of breed, nutrition and management. The effect of free-range and semi-feed lot feeding strategies on the eating quality of beef from Zebu and Sahiwal breeds was assessed. A 2 x 2 between subjects factorial design was used (two breeds fed using two feeding strategies). From each single breed and feeding strategy combination, seven cattle were selected after three months of feeding. The cattle were slaughtered and their rump steaks sampled. The samples were frozen for 24 h then thawed for 4 h prior to analysis. The steaks' pH was measured after cooking. They were then subjected to Texture Profile Analysis (TPA), 'Warner-Bratzler' Shear (WBS) tests, and organoleptic evaluations. The pH did not differ significantly with feeding strategy or breed (P≥0.05). The result from TPA and WBS revealed that semi feed-lot Sahiwal beef was tender than free-range Sahiwal beef (P<0.05). On the other hand, there was no difference in tenderness between feed-lot and free-range Zebu beef (P≥0.05). An analysis between the breeds showed that feed-lot Sahiwal beef was tender than feed-lot Zebu beef (P<0.05), but there was no difference in tenderness between beef from free-range Sahiwal and free-range Zebu (P≥0.05). In the sensory analysis, there was a significant difference for each of the sensory parameters (P<0.05, each). Steaks from semi-feed lot Sahiwal were preferred to the other beef steaks. In conclusion, a semi-feed lot feeding strategy has the potential to improve the eating quality of beef from Sahiwal breed. Nevertheless, the improvement in the eating quality observed with Zebu breed, although not statistically significant, gives an opportunity for value chain actors to explore other management systems that can be combined with those assessed in this study to improve eating quality. [ABSTRACT FROM AUTHOR]

Degraded animal fats, characterised by the presence of palmitic (C) and stearic (C) fatty acids and related glycerolipids are the most common class of preserved lipids in organic residues trapped in the porous clay matrix of archaeological ceramic vessels. The ubiquitous presence of fatty acids in animal fats and plant oils precludes identification of fat types by the solely molecular composition of residues. Hence, animal fats are identified by determining their fatty acyl lipid distributions and stable carbon (δC) values allowing distinctions to be drawn between non-ruminant and ruminant, and dairy and adipose fats. The ΔC proxy (= δC - δC) originally proposed in the 1990s by Evershed and co-workers was based on modern reference fats sampled from animals raised in Britain on C plant diets. Further analyses on adipose and dairy fats from ruminants grazing in a wide range of isoscapes have shown that the ΔC proxy can be applied in mixed C/C environments, such as in Africa. Here we show, however, through the investigation of milk fats, how the ΔC proxy can be perturbed when animals are reared on modern diets, specifically maize silage. It is thus shown that extreme care has to be taken when choosing modern reference fats for archaeological studies, and especially that insecurely sourced animal fats should be excluded from such databases. [ABSTRACT FROM AUTHOR]

A 2-yr study was conducted to determine effects of N fertilization level on fiber digestion kinetics and protein degradability characteristics of stockpiled Tifton 85 bermudagrass (T85). Six 0.76-ha pastures of stockpiled T85 were cut to a 10-cm stubble height on August 1 of each yr and fertilized with 56 (56N), 112 (112N), or 168 (168N) kg N/ha (2 pastures/treatment). Fiber digestion kinetics included the 72-hr potential extent of NDF digestion (PED), rate of NDF digestion, and lag time. In yr 1 and 2, PED decreased over the stockpile season. Rates of NDF digestion did not differ (P > 0.05) among N fertilization treatments in either yr. In yr 1, rate of NDF digestion was greatest (P < 0.05) in October/November, and decreased beginning in December. In yr 2, rate of NDF digestion decreased (P < 0.05) in January compared with November, but digestion rates were similar for November and January 21 sampling dates. Lag time was greater (P < 0.05) for the 112N than 56N and 168N treatments, and increased (P < 0.05) across sampling dates in yr 1. In yr 2, lag time increased (P < 0.05) from 9.0 to 17.7 h across the season. In yr 1 and 2, a negative correlation (P < 0.05) between forage lignin concentration and both PED (r = -0.91 and -0.87 in yr 1 and 2, respectively) and rate of NDF digestion (r = -0.60 and -0.25 in yr 1 and 2, respectively) was observed. There was a trend (P = 0.06) for lignin concentration to be positively correlated with lag time (r = 0.39) in yr 1, and a strong relationship was observed in yr 2 (r = 0.91; P < 0.05). The RDP fraction as a % of CP was ≥ 90% throughout both years. Concentration of RDP (% of total DM) decreased across the stockpiling season through January in yr 1 and 2. Results suggest that kinetic parameters of NDF digestion in stockpiled T85 were influenced more by temporal changes over the stockpile season than by N fertilization level. Supplement formulations based on kinetic parameters of fiber digestion may require periodic adjustment to insure that energy-yielding components of NDF are sufficient to meet animal requirements throughout the stockpile season. The CP fraction in stockpiled T85 contains sufficient RDP to support fibrolytic activity and growth of ruminal microorganisms throughout the stockpile season. Toward the latter end of the season, supplementation with sources of digestible fiber and RDP could be expected to increase MP supply to the host animal. [ABSTRACT FROM AUTHOR]

Four Thai native steers were used to determine the adequate levels of supplementary desalted mother liquor ( DML) for energy and nitrogen balances and ruminal fermentation. The crude protein and sodium chloride contents of DML were 25.5% and 60.3% on a dry matter (DM) basis, respectively. A 4 × 4 Latin square design experiment was conducted by adding different amounts of DML to three experimental diets (T1: 1.1%, T2: 2.2%, T3: 3.4% sodium chloride concentration with supplementary DML on a DM basis) and comparing their effects with those of a control diet (C) containing 1.0% commercial salt on a DM basis. The animals were given the experimental diets and rice straw daily at 1.2% and 0.8% of body weight, respectively, on a DM basis. No significant differences in the apparent digestibility of nutrients were observed among treatments. T3 achieved the lowest nitrogen retention ( P < 0.05), followed by C, T2 and T1. The ratios of energy retention to gross energy were higher in T1 and T3 than T2, and that in C was lowest ( P < 0.05). Supplementary NaCl concentration at 1% and 2% can be replaced with DML without an adverse effect on the digestibility of nutrients or on the nitrogen and energy retention. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the inclusion of technical cashew nut shell liquid (tCNSL) in the concentrate for cattle fed on a high-grain diet on feed intake, ruminal and total apparent digestibility coefficients of nutrients, fermentation characteristics and microbial efficiency. Four Holstein steers (445 ± 23.39 kg of body weight) fitted with ruminal and duodenal cannulae were used. The diets had (in DM basis) 144 g kg-1 of crude protein and 799 g kg-1 of total digestible nutrients, with a forage to concentrate ratio of 15:85. The experimental design was a 4 x 4 Latin square with 10-day experimental periods. The diets consisted of 0; 300; 600 and 1200 mg of tCNSL in DM of the concentrate. Intake and total apparent digestibility coefficient of nutrients, on DM basis, were not affected by experimental diets. However, ruminal digestibility of ether extract showed quadratic response in which animals fed 0 and 300 mg tCNSL kg-1 of concentrate had the lowest values for ruminal digestibility. Ruminal ammonia nitrogen, plasma urea nitrogen and microbial efficiency were not affected by treatments. However, ruminal pH tended to increase when animals were fed with tCNSL. [ABSTRACT FROM AUTHOR]

Objective: This study was aimed at evaluating effects of cattle breed resources and alternative mixed-feeding practices on meat productivity and emission intensities from household farming systems (HFS) in Daklak Province, Vietnam. Methods: Records from Local Yellow×Red Sindhi (Bos indicus; Lai Sind) and 1/2 Limousin, 1/2 Drought Master, and 1/2 Red Angus cattle during the growth (0 to 21 months) and fattening (22 to 25 months) periods were used to better understand variations on meat productivity and enteric methane emissions. Parameters were determined by the ruminant model. Four scenarios were developed: (HFS1) grazing from birth to slaughter on native grasses for approximately 10 h plus 1.5 kg dry matter/d (0.8% live weight [LW]) of a mixture of guinea grass (19%), cassava (43%) powder, cotton (23%) seed, and rice (15%) straw; (HFS2) growth period fed with elephant grass (1% of LW) plus supplementation (1.5% of LW) of rice bran (36%), maize (33%), and cassava (31%) meals; and HFS3 and HFS4 computed elephant grass, but concentrate supplementation reaching 2% and 1% of LW, respectively. Results: Results show that compared to HFS1, emissions (72.3±0.96 kg CH4/animal/life; least squares means± standard error of the mean) were 15%, 6%, and 23% lower (p<0.01) for the HFS2, HFS3, and HFS4, respectively. The predicted methane efficiencies (CO2eq) per kg of LW at slaughter (4.3±0.15), carcass weight (8.8±0.25 kg) and kg of edible protein (44.1±1.29) were also lower (p<0.05) in the HFS4. In particular, irrespective of the HSF, feed supply and ratio changes had a more positive impact on emission intensities when crossbred 1/2 Red Angus cattle were fed than in their crossbred counterparts. Conclusion: Modest improvements on feeding practices and integrated modelling frameworks may offer potential trade-offs to respond to climate change in Vietnam. [ABSTRACT FROM AUTHOR]

Background: Single nucleotide polymorphism (SNP) arrays for domestic cattle have catalyzed the identification of genetic markers associated with complex traits for inclusion in modern breeding and selection programs. Using actual and imputed Illumina 778K genotypes for 3887 U.S. beef cattle from 3 populations (Angus, Hereford, SimAngus), we performed genome-wide association analyses for feed efficiency and growth traits including average daily gain (ADG), dry matter intake (DMI), mid-test metabolic weight (MMWT), and residual feed intake (RFI), with marker-based heritability estimates produced for all traits and populations. Results: Moderate and/or large-effect QTL were detected for all traits in all populations, as jointly defined by the estimated proportion of variance explained (PVE) by marker effects (PVE ≥ 1.0%) and a nominal P-value threshold (P ≤ 5e-05). Lead SNPs with PVE ≥ 2.0% were considered putative evidence of large-effect QTL (n = 52), whereas those with PVE ≥ 1.0% but < 2.0% were considered putative evidence for moderate-effect QTL (n = 35). Identical or proximal lead SNPs associated with ADG, DMI, MMWT, and RFI collectively supported the potential for either pleiotropic QTL, or independent but proximal causal mutations for multiple traits within and between the analyzed populations. Marker-based heritability estimates for all investigated traits ranged from 0.18 to 0.60 using 778K genotypes, or from 0.17 to 0.57 using 50K genotypes (reduced from Illumina 778K HD to Illumina Bovine SNP50). An investigation to determine if QTL detected by 778K analysis could also be detected using 50K genotypes produced variable results, suggesting that 50K analyses were generally insufficient for QTL detection in these populations, and that relevant breeding or selection programs should be based on higher density analyses (imputed or directly ascertained). Conclusions: Fourteen moderate to large-effect QTL regions which ranged from being physically proximal (lead SNPs ≤ 3Mb) to fully overlapping for RFI, DMI, ADG, and MMWT were detected within and between populations, and included evidence for pleiotropy, proximal but independent causal mutations, and multi-breed QTL. Bovine positional candidate genes for these traits were functionally conserved across vertebrate species. [ABSTRACT FROM AUTHOR]

We evaluated the effects of different methods for conserving and crushing rice grain on rumen fermentation characteristics and whole-tract apparent digestibility in steers. The preparation of dietary treatments followed a 2 × 2 factorial design with conservation method (drying vs . ensiling) and crushing method (using an impeller crusher vs . a double–roller crusher) of rice grain as main effects. Rice grain was crushed by the impeller crusher (volume weight: 490.4 g/L, mean particle size: 1382 μm) or the double–roller crusher (volume weight: 373.9 g/L, mean particle size: 2043 μm). Dried rice was prepared by drying to adjust the moisture to 100 g kg −1 . Ensiled rice was prepared by sealing crushed rice with the addition of water and lactic acid bacteria to adjust the moisture to 300 g kg −1 , and stored for 4 months. Eight ruminally cannulated steers (366 ± 32.2 kg initial body weight [BW]) were randomly assigned to a replicated 4 × 4 Latin square design. The experimental diets contained 434 g kg −1 grass silage, 96 g kg −1 soybean meal and 470 g kg −1 treated rice grain (dry matter [DM] basis). Steers were offered experimental diets at 1.55 kg DM/100 kg of BW/day. The conservation method had a large impact on the ruminal fermentation and nutrient digestibility. The ruminal fermentation characteristics and nutrient digestibility (except for starch digestibility) were not affected by the crushing method. No significant interactions were observed between the conservation and crushing methods of rice grain for all fermentation and digestion measurements. The ruminal pH was lower ( P < 0.01) and the lactic acid and total volatile fatty acid concentrations were higher ( P < 0.01 and P = 0.02, respectively) for the steers fed ensiled rice than those fed dried rice. The proportions of acetate, propionate and butyrate were not affected by ensiling treatment. The whole-tract apparent digestibility of organic matter, crude protein and starch were increased ( P = 0.04, P < 0.01 and P < 0.01, respectively) and the digestibility of neutral detergent fiber and acid detergent fiber were decreased ( P = 0.046 and P = 0.03, respectively) by replacing dried rice with ensiled rice. The starch digestibility was higher ( P < 0.01) for steers fed rice crushed by the impeller crusher compared to the double-roller crusher. These results show that the feeding of ensiled instead of dried rice increases the likelihood of decreasing fiber digestibility because it reduces ruminal pH, but it improves organic matter, crude protein and starch digestion, and thus an ensiling process can be a strategy to improve the nutrient value of rice grain. [ABSTRACT FROM AUTHOR]

Lipid supplementation may adversely affect rumen fermentation, microbial abundance, nutrient utilization and the duodenal flow of fatty acids (FA). In a 5 × 5 Latin square design, 10 Nellore steers with ruminal and duodenal cannulas (292 ± 28 kg BW) were fed one of the five following dietary lipid sources in the concentrate, as follow: (1) no additional fat (WF); (2) palm oil (PO) derived from the Palmaceae plant Orbignya oleifera ; (3) linseed oil (LO); (4) protected fat (PF); and (5) whole soybeans (WS). The dry matter intake (DMI) was greater for the animals supplemented with WF than for those supplemented with PO, PF, and WS. The DM digestibility was 11% greater for the animals in the WF group than for those in the PO group. The animals in the PO group had greater duodenal flows of capric (C10:0), lauric (C12:0) and myristic (C14:0) saturated fatty acids (SFA) than did animals in the other groups. The amount of flows of vaccenic acid and total unsaturated acids (UFA) was greater with LO supplementation. The unsaturated fatty acid (UFA) biohydrogenation ratio was greater in the animals supplemented with WS than in those supplemented with PO, LO, and PF. The acetate: propionate ratio was lower in the animals supplemented with PO and LO, at 2.9 and 3.0, respectively. The ruminal flow of particles and rate of fiber degradation were lower with PO supplementation. The proportion of archaea was reduced with the inclusion of PO, LO and PF. PO supplementation resulted in lower total apparent NDF digestibility than did WF, PF, and WS supplementation. Therefore, LO, PF and WS can be used as dietary supplements for grazing cattle without impairing fermentation. The inclusion of PO in the diets of grazing cattle may reduce the number of methanogens and alter fiber utilization. [ABSTRACT FROM AUTHOR]

Methane (CH4) loss from finishing cattle is important as it represents an energy loss that could be used for maintenance and growth, and CH4 is a greenhouse gas with a global warming potential 21 to 25 times that of CO2. Our objectives were to determine hourly CH4 production from growing cattle fed diets differing in corn processing method (dry rolling or steam flaking) and wet distillers grains with solubles (WDGS) inclusion rate. Eight steers (195 kg ± 2.3 in Exp. 1 and 322 kg ± 3.7 in Exp. 2) were fed the following diets: 1) steam-flaked corn (SFC)-based diet with 0% WDGS (SFC-0); 2) SFC-based diet with 15% WDGS (SFC-15); 3) SFC-based diet with 30% WDGS (SFC-30); 4) SFC-based diet with 45% WDGS (SFC-45); 5) Dry-rolled corn (DRC)-based diet with 0% WDGS (DRC-0); and 6) DRC-based diet with 30% WDGS (DRC-30). All hourly CH4 data were analyzed using the MIXED procedure of SAS. Individual animal was the experimental unit. The model included the fixed effect of h, diet, and the h × diet interaction. Hourly differences in CH4 were analyzed using repeated measures. There were numerous h × diet interactions and thus simple-effect means are presented. In steers fed DRC-0 or DRC-30 at 2-times maintenance, the greatest hourly CH4 emissions occur 6 h after feeding (P < 0.01) with a secondary peak between 10 and 11 h after feeding (P < 0.01). For cattle fed SFC-0, SFC-15, SFC-30, and SFC-45 at 2-times maintenance, all diets had peak CH4 emissions 5 and 6 h after feeding (P < 0.01), with a secondary CH4 peak for SFC-45 nine to 11 h after feeding (P < 0.01). Cattle fed all diets at a maintenance level of intake exhibited 1 peak in hourly CH4 production between 3 and 6 h after feeding (P < 0.01). All steers fed SFC-30 and SFC-45 had sustained CH4 production over several hours, irrespective of intake level. Steers fed SFC-45 produced more CH4 beginning 4 h after feeding (P < 0.01) and produced a greater amount of CH4 than any other treatment (P < 0.01). Methane production generally peaked 6 h after feeding irrespective of intake level or diet type. Additionally, when fed above a maintenance level of intake, a secondary peak in CH4 production was observed 9 to 11 h after feeding, and steers fed at a maintenance level of intake had only 1 peak in CH4 production in a 23-h period. [ABSTRACT FROM AUTHOR]

The effects of handling intensity on the physiological response and carcass characteristics of feedlot cattle fed ractopamine hydrochloride were evaluated at the time of transport to slaughter. Eighty steers (BW = 668 ± 36 kg) representing 10 lots of similar breed, frame size, and degree of finish were blocked by lot, stratified by weight, and randomly assigned to 1 of 2 handling intensities (HI) over a 1,600 m dirt alley course: 1) low-stress handling (LSH) or 2) high-stress handling (HSH). For the LSH treatment, 4 penmates were kept at a walk with the use of a lead rider. For the HSH treatment, 4 penmates were kept at a minimum of a trot and received 2 applications of an electric prod (approximately 1 s per impulse) at 2 separate instances: first in the alley before post-handling sampling, and again during loading for transportation to the abattoir. Behavioral observations and physical indicators of stress were recorded a minimum of 1 h before handling (baseline), immediately after handling (POSTHAND), and while in lairage after a 200 km transport to the abattoir. Vital parameters were recorded at baseline and POSTHAND. Venous blood samples were collected via jugular venipuncture at baseline and POSTHAND, and mixed arterial and venous blood samples were collected during exsanguination at slaughter. Muscle tremors tended to be more prevalent in HSH cattle at POSTHAND (P = 0.10). The HSH cattle tended to have greater POSTHAND heart rate (P = 0.08); however, there was no effect of HI on POSTHAND respiration rate or rectal temperature (P ≥ 0.34). The HSH cattle had greater lactate, epinephrine, norepinephrine, cortisol, and glucose concentrations at POSTHAND (P ≤ 0.02). Additionally, HSH cattle had lower POSTHAND blood pH, bicarbonate, base excess, and partial pressure carbon dioxide (P < 0.0001). Bicarbonate concentrations were greater in HSH cattle at slaughter (P = 0.05); however, there were no differences between HI treatments for the remaining blood variables (P ≥ 0.11). Concentrations of stress hormones and CK were significantly greater at slaughter relative to baseline and POSTHAND for both LSH and HSH cattle (P < 0.001). These findings suggest cattle trotted without a lead rider develop metabolic acidosis, and illustrate the importance of low-stress handling at the time of transport for slaughter. Further research is warranted to develop strategies to mitigate stress at the time of transport and ensure the welfare of beef cattle presented to abattoirs. [ABSTRACT FROM AUTHOR]

The effect of restricting the time of access to a high-quality fresh forage on the intake and digestion of nutrients was studied in heifers. Twenty-four Hereford heifers (body weight (BW) 153 ± 18 kg) housed in metabolic cages were randomized according to a BW-based block design and were randomly assigned to receive one of the four following treatments: 24, 8, 6 or 4 h of daily access to freshly cut pasture ( Lolium multiflorum and Trifolium repens ) (T24, T8, T6 and T4, respectively). Their feeding behavior (classified according to the categories of ‘eating’, ‘ruminating’ or ‘other’), intake rate, intake and digestibility of nutrients, ruminal environment, microbial protein synthesis and blood markers of energy and protein metabolism were assessed. The intake for all of the feed fractions decreased at an increasing rate (from 6 h of access) as the time of access to forage decreased (linear: P < 0.001; quadratic: P < 0.035). During the first 4 h of feeding, animals linearly increased the eating time and the intake rate ( P < 0.001 and P = 0.006, respectively), and decreased the ruminating time ( P = 0.014) as the time of access to forage decreased. Neither forage digestibility, nor ruminal microbial protein synthesis efficiency, were affected by the restrictions. The metabolizable energy balance linearly decreased ( P < 0.001) and N retention decreased at an increasing rate (from 8 h of access; linear: P < 0.003, quadratic P < 0.030), with decreasing time of access to forage. The ruminal pH and NH 3 -N concentration were affected by treatment and time ( P < 0.001). Ruminal pH increased at an increasing rate (from 8 h of access) as the time of access to forage decreased. Meanwhile, NH 3 -N concentration linearly decreased as the time of access to forage decreased. There was a significant interaction between treatment and time for pH and NH 3 -N ( P < 0.001), being both variables less stable during the day in restricted animals than in unrestricted ones. The concentrations of blood glucose, urea and insulin were not affected by the restrictions. In general, the effects of the restriction seem to have been less evident on digestion than on ingestion. Fasting beef heifers led to behavioral changes in order to maintain the dry matter intake, but these changes resulted insufficient when the time of access to forage drops below 6 h per day. [ABSTRACT FROM AUTHOR]

It was hypothesized that replacement of corn with soybean hulls as the energy source, combined with ground soybean as the lipid source, would reduce methane emissions from feedlot animals without affecting their performance. This study aimed to evaluate the effects of including ground soybean combined with either a high or a low level of starch on intake, digestibility, performance, and methane emission of young Nellore bulls (n = 28, initial weight = 395 ± 32 kg) in the feedlot during the finishing phase. Diet treatments consisted of high (HS; approx. 250 g/kg) or low (LS; approx. 110 g/kg) starch levels, with (WSB) or without (NSB) soybean. Ground soybean was added as a lipid source to diets HS-WSB, LS-WSB, HS-NSB, and LS-NSB, representing 58.7, 64.6, 24.8, and 31.4 g/kg ether extract in the total dry matter, respectively. Animals were distributed in a completely randomized design, in a 2 × 2 factorial arrangement. After 119 days, the animals were slaughtered. Animals fed soybean demonstrated an average reduction of 11% in their intakes of dry matter, organic matter, and crude protein (P = 0.01). There was a significant effect of the association between starch and soybean on neutral detergent fiber intake (P = 0.01). Diets containing soybean affected the digestibility of the animals, reducing the apparent digestibility of dry matter by 3% (P = 0.02) and the digestibility of organic matter by 2.8% (P = 0.03). A significant interaction was detected between starch and soybean on the apparent digestibility of ether extract (P = 0.02) and neutral detergent fiber (P = 0.04); the lowest values for ether extract (750 g/kg) and neutral detergent fiber (432 g/kg) were obtained with HS-WSB. The animals that received WSB had their feed efficiency increased by 17% (P = 0.01). The enteric CH 4 emissions of the animals fed WSB reduced significantly (P = 0.01), with 28% decrease in g CH 4 /d and g CH 4 /y, 16% decrease in g CH 4 per kg of dry matter intake, and 23% decrease in CH 4 losses per percent of gross energy intake. The inclusion of approximately 250 g/kg of soybean in the diet of young Nellore bulls in the feedlot provides an increase in their feed efficiency and reduces their enteric methane emission, regardless of the level of starch in the concentrate. [ABSTRACT FROM AUTHOR]

Our objective was to evaluate the effect of Cu, Zn, and Mn source on measures of 1) preferential intake of mineral-concentrated supplements and 2) mineral status and pre- and postweaning performance of beef calves. In Exp. 1, 4 trials were conducted to assess the effect of source of Cu (750 mg/kg; Trial 1), Zn (2,000 mg/kg; Trial 2), Mn (3,000 mg/kg; Trial 3), and all 3 elements (Trial 4) on preferential intake of mineral-concentrated supplements. Supplements differed only by source of Cu, Zn, and Mn, which included hydroxychloride (hydroxy), sulfate, and organic options. In each trial, the 3 supplements were simultaneously offered to 8 pens of early-weaned calves (2 calves/pen; 126 ± 8.0 kg average BW) for a 4-h period and preferential intake was determined. When offered the opportunity to select among 3 supplement options, calves consumed more (P < 0.001) supplement containing hydroxy vs. organic or sulfate sources of Cu (Trial 1), Zn (Trial 2), and Mn (Trial 3). In Trial 4, when all 3 elements were combined within a single supplement, calves almost exclusively selected (P < 0.001) the hydroxy vs. organic or sulfate sources (82.9, 10.4, and 6.7% of total supplement intake, respectively [SEM 3.16]). In Exp. 2, calves were supplemented at a rate of 114 g/calf daily for 84 d before weaning (2 calves/pasture; 10 and 12 pastures in yr 1 and 2, respectively). Supplements were formulated to contain no supplemental minerals (control); hydroxy Cu, Zn, and Mn; or copper sulfate, zinc sulfate, and manganese oxide (sulfate/oxide). Total supplement intake was greater (P = 0.01) for calves consuming the hydroxy vs. the sulfate/oxide sources of Cu, Zn, and Mn (9.0 vs. 7.2 kg [SEM 0.45]). Preweaning calf BW gain did not differ (P = 0.15) among treatments; however, calves provided mineral-fortified supplements had greater (P = 0.003) liver concentrations of Co and Se and tended (P = 0.07) to have greater liver concentrations of Cu at weaning compared with the controls. Calves provided mineralfortified vs. control supplements had greater (P = 0.05) peak concentrations of ceruloplasmin and haptoglobin and less BW gain during in the 16-d postweaning period. These data demonstrate greater voluntary intake of mineral-concentrated supplements among calves offered hydroxy vs. sulfate or organic sources of Cu, Zn, and Mn. Preweaning mineral-fortified supplementation increased calf mineral status, heightened inflammatory responsiveness, and decreased BW gain during the immediate postweaning period. [ABSTRACT FROM AUTHOR]

This study evaluated intake, microbial efficiency, and ruminal, small and large intestinal, and total digestibility of DM, OM, CP, and NDF, as well as availability of Ca, P, Mg, Na, K, Cu, Mn, and Zn in Zebu cattle fed with or without supplemental sources of Ca and P or a micromineral premix. Five rumenand ileum-cannulated Nellore bulls (BW = 200 ± 10.5 kg; 9 mo) were used in the experiment, distributed in a 5 × 5 Latin square design. The experiment was developed in a 2 × 2 + 1 factorial design to measure the effects of mineral supplementation on intake, digestibility, and site of nutrient absorption. The factors consisted of 2 Ca and P levels (macromineral factor; CaP+ or CaP-) and 2 microminerals levels (micromineral factor; CuMnZn+ or CuMnZn-). In addition, a treatment with alimentary restriction (REST) was evaluated at 1.7% of BW. Nutrient fluxes were measured in the omasum and ileum, in addition to intake and fecal excretion. Microbial efficiency was estimated using purine derivative excretion. Dry matter, OM, NDF, CP intake, and total digestibility were not affected (P = 0.058) by the absence of Ca, P, Cu, Mn, and Zn supplementation. Intake of Ca, P, and Mg were reduced (P < 0.01) by CaP-. The absence of CuMnZn reduced (P < 0.01) Cu, Mn, and Zn intake. Ruminal recycling of P, Na, and K is significant for increasing the influx of these minerals to the digestive tract; however, influences of treatments were not observed. The small and large intestines contributed to mineral absorption in different proportions (P < 0.05), according to minerals and treatments. Because of the similarity (P > 0.05) of OM, NDF, and CP digestion sites and coefficients, we assume that omitting supplemental sources of Ca, P, Cu, Mn, and Zn may be an option in raising cattle on feedlots. If supplementation is viable, knowledge about the specific absorption site of each mineral could positively impact choices about the supplemental source. [ABSTRACT FROM AUTHOR]

Roughage is fed in finishing diets to promote ruminal health and decrease digestive upset, but the inclusion rate is limited because of the cost per unit of energy and feed management issues. Rumination behavior of cattle may be a means to standardize roughage in beef cattle finishing diets, and increasing the particle size of roughage could modulate the ruminal environment and aid in maintaining ruminal pH. Therefore, this experiment was conducted to determine the effects of corn stalk (CS) inclusion rate and particle size in finishing diets on digestibility, rumination, and ruminal fermentation characteristics of beef steers. Four ruminally cannulated steers were used in a 4 × 4 Latin square experiment. Treatments were arranged as a 2 × 2 factorial with treatments consisting of 5% inclusion of a short-grind roughage (5SG), 10% inclusion of a short-grind roughage (10SG), 5% inclusion of a long-grind roughage (5LG), and 10% inclusion of a long-grind roughage (10LG). Differences in particle size were obtained by grinding corn stalks once (LG) or twice (SG) using a commercial tub grinder equipped with a 7.6-cm screen and quantified using the Penn State Particle Separator (PSPS) to estimate physically effective NDF (peNDF). Each period included 14 d for adaptation and 4 d for diet, fecal, and ruminal fluid collections. Animals were outfitted with rumination monitoring collars to continuously measure rumination activity. The 10LG treatment had a greater (P < 0.01) percentage of large particles (retained on the top 3 sieves of the PSPS) compared to the other treatments. This resulted in a greater (P < 0.01) percentage of estimated peNDF for the 10LG diet compared to the others. Feeding diets containing 5% roughage tended to increase (P = 0.09) DM, NDF, and starch total tract digestibility compared to diets containing 10% roughage. Cattle consuming LG treatments had greater (P < 0.01) rumination time and greater (P < 0.01) ruminal pH than cattle consuming diets containing SG roughage. Cattle receiving the 5% inclusion rate of roughage tended to have greater (P = 0.09) time (h/d) under a ruminal pH of 5.6 and a larger (P = 0.03) area under the threshold compared to cattle receiving the 10% roughage treatments. Overall, feeding a lower inclusion of roughage with a larger particle size may stimulate rumination and aid in ruminal buffering similar to that of a higher inclusion of roughage with a smaller particle size, without negatively impacting digestibility and fermentation. [ABSTRACT FROM AUTHOR]

The objectives of this study were to quantify the mineral balance of Nellore cattle fed with and without Ca, P, and micromineral (MM) supplementation and to estimate the net and dietary mineral requirement for Bos indicus cattle. Nellore cattle (n = 51; 270.4 ± 36.6 kg initial BW and 8 mo age) were assigned to 1 of 3 groups: reference (n = 5), maintenance (n = 4), and performance (n = 42). The reference group was slaughtered prior to the experiment to estimate initial body composition. The maintenance group was used to collect values of animals at low gain and reduced mineral intake. The performance group was assigned to 1 of 6 treatments: sugarcane as the roughage source with a concentrate supplement composed of soybean meal and soybean hulls with and without Ca, P, and MM supplementation; sugarcane as the roughage source with a concentrate supplement composed of soybean meal and ground corn with and without Ca, P, and MM supplementation; and corn silage as the roughage source with a concentrate supplement composed of soybean meal and ground corn with and without Ca, P, and MM supplementation. Orthogonal contrasts were adopted to compare mineral intake, fecal and urinary excretion, and apparent retention among treatments. Maintenance requirements and true retention coefficients were generated with the aid of linear regression between mineral intake and mineral retention. Mineral composition of the body and gain requirements was assessed using nonlinear regression between body mineral content and mineral intake. Mineral intake and fecal and urinary excretion were measured. Intakes of Ca, P, S, Cu, Zn, Mn, Co, and Fe were reduced in the absence of Ca, P, and MM supplementation (P < 0.05). Fecal excretion of Ca, Cu, Zn, Mn, and Co was also reduced in treatments without supplementation (P < 0.01). Overall, excretion and apparent absorption and retention coefficients were reduced when minerals were not supplied (P < 0.05). The use of the true retention coefficient instead of the true absorption coefficient provided a better estimate of mineral requirements. Dietary mineral requirements were lower for P, Cu, and Zn and greater for Fe compared with previously published recommendations. This study provides useful information about mineral requirements and mineral supplementation to obtain adequate dietary mineral supply of Nellore cattle in tropical conditions. [ABSTRACT FROM AUTHOR]

Four adult Simmental male cattle (376 ± 9.0 kg initial BW), fitted with permanent rumen cannulas, were used in a 4 × 4 Latin square design to investigate the effects of dietary supplementing tannic acid ( TA) on rumen fermentation, methane (CH4) production, rumen microbes, nutrient digestibility and plasma biochemical parameters. Four levels of TA, that is 0, 6.5, 13.0 or 26.0 g/kg dry matter ( DM), were added to the basal ration (composed of corn silage and concentrate mixture) as experimental treatments respectively. Each experimental period consisted of a 12-day adaptation phase followed by a 3-day sampling phase. The results showed that supplementing TA at 26.0 g/kg DM decreased the relative abundance of protozoa, methanogens and Ruminococcus albus to the total ruminal bacterial 16S rDNA in beef cattle (p < 0.05). The results also showed that supplementing TA at 6.5, 13.0 or 26.0 g/kg DM decreased (p < 0.01) the CH4 production (l/kg DM intake) by 11.1%, 14.7% and 33.6% respectively. Supplementing TA at 13.0 or 26.0 g/kg DM decreased the ratio of acetate to propionate and ammonia nitrogen ( NH3-N) (p < 0.05) and tended to decrease the total volatile fatty acid (VFA) concentration of rumen fluid (p = 0.07). Supplementing TA at 26.0 g/kg DM decreased DM and organic matter (OM) digestibility (p < 0.05), supplementing TA at 6.5, 13.0 or 26.0 g/kg DM decreased (p < 0.01) crude protein ( CP) digestibility by 5.0%, 8.6% and 15.7%, respectively, and supplementing TA at 6.5, 13.0 or 26.0 g/kg DM increased (p < 0.05) the plasma total antioxidant capability. It was concluded that supplementing TA in the ration of beef cattle decreased the CH4 production and digestibility of CP of beef cattle. Supplementing TA could be an effective option to mitigate CH4 emission form cattle, further research is necessary to study the effects of TA on the performance of cattle. [ABSTRACT FROM AUTHOR]

Objective: The effects of particle size of processed barley grain, enzyme addition and microwave treatment on in vitro dry matter (DM) disappearance (DMD), gas production and fermentation pH were investigated for feedlot cattle. Methods: Rumen fluid from four fistulated feedlot cattle fed a diet of 860 dry-rolled barley grain, 90 maize silage and 50 supplement g/kg DM was used as inoculum in 3 batch culture in vitro studies. In Experiment 1, dry-rolled barley and barley ground through a 1-, 2-, or 4-mm screen were used to obtain four substrates differing in particle size. In Experiment 2, cellulase enzyme (ENZ) from Acremonium cellulolyticus Y-94 was added to dry-rolled and ground barley (2-mm) at 0, 0.1, 0.5, 1, and 2 mg/g, while Experiment 3 examined the interactions between microwaving (0, 30, and 60 s microwaving) and ENZ addition (0, 1, and 2 mg/g) using dry-rolled barley and 2-mm ground barley. Results: In Experiment 1, decreasing particle size increased DMD and gas production, and decreased fermentation pH (p<0.01). The DMD (g/kg DM) of the dry-rolled barley after 24 h incubation was considerably lower (p<0.05) than that of the ground barley (119.1 dry-rolled barley versus 284.8 for 4-mm, 341.7 for 2-mm; and 358.6 for 1-mm). In Experiment 2, addition of ENZ to dry-rolled barley increased DMD (p<0.01) and tended to increase (p = 0.09) gas production and decreased (p<0.01) fermentation pH, but these variables were not affected by ENZ addition to ground barley. In Experiment 3, there were no interactions between microwaving and ENZ addition after microwaving for any of the variables. Microwaving had minimal effects (except decreased fermentation pH), but consistent with Experiment 2, ENZ addition increased (p<0.01) DMD and gas production, and decreased (p<0.05) fermentation pH of dry-rolled barley, but not ground barley. Conclusion: We conclude that cellulase enzymes can be used to increase the rumen disappearance of barley grain when it is coarsely processed as in the case of dry-rolled barley. However, microwaving of barley grain offered no further improvements in ruminal fermentation of barley grain. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate herbage dry matter intake in 16 beef cows which grazed continuously on permanent pastures within the "The Warta Estuary" National Park (Poland), using the minimally invasive method based on n-alkanes as markers (C29, C31, C33). Significant differences were observed in the nutritive value of herbage collected for analyses by cutting or nipping. The calculated content of energy and protein in the nipped herbage was higher: UFL by 58.1% and PDI by 50%, with a higher digestibility of nutrients. The values obtained for DM intake in pasture herbage by cows were closest to the standards when calculations were based on the C29/C32 pair of n-alkanes. However, the best prediction of DM intake estimation from creeping bentgrass (Agrostis stolonifera) pasture, in agreement with the accepted energy and protein standards, was based on the proportions between alkanes C31/C32. [ABSTRACT FROM AUTHOR]

Reducing daily methane production (DMP) via selection for lower estimated daily (pasture) feed intake (DFI) has the potential to be more cost effective than direct selection for DMP. Daily feed intake has a high heritability and high genetic correlation to DMP and has a potential lower cost of measurement. This study's main aim was to determine for a breeding nucleus the optimal proportion of randomly selected young male and female cattle in which to estimate DFI. This optimum proportion was determined by modeling the measurement costs and response to selection of Angus cattle on a (standard industry) Angus breeding index (ABI) augmented with DFI and DMP in a combined breeding objective (BO), but without DMP being measured. For the assumed herd structure and considering a 20 yr planning horizon, the highest net present value (NPV) occurred when 64% of males and no females were measured for DFI. The highest breakeven DFI test cost (A$41.51/head) and highest returns on investment (ROI) occurred when 36% of males and no females had DFI estimates. Higher ROI were achieved when all males had DFI estimates before any females had DFI estimates. There was a diminishing increase in rate of genetic gain when moving from 36% to 64% of males with DFI estimates, thus ROI decreased from 29.7% to 23.1%. When 36% of males had DFI estimates (and no females), herd DMP genetic gain was slightly positive as the DMP reduction per generation from male selection (-0.086) was more than offset by the DMP increase per generation from female selection (+0.110). The selection response for DMP only became negative when at least 40% of males had DFI estimates. Having 64% of males with DFI estimates resulted in a predicted genetic decrease in DMP (-0.018 kgCO2e/head per yr), compared to an increase of 0.052 kgCO2e/head per yr when no animals had DFI estimates. The optimum proportion of males with DFI estimates (36 to 64%) depends on the breeders attitude toward ROI and the value of genetic change for DMP. Sensitivity analysis showed that the economic value (EV), heritability and genetic variance of DFI had a higher impact on the NPV and ROI outcomes than parameters related to ABI and DMP, so future work should focus on obtaining robust estimates for DFI parameters. Higher EV for feed intake and DMP would result in higher percentages of animals being profitably measured for DFI, leading to larger reductions in DMP. [ABSTRACT FROM AUTHOR]

Dose response curves to various supplements were established in two pen-feeding experiments (Exp1 and Exp2) with Bos indicus crossbred steers of two age groups Young, 10-12 months; Old, 33-36 months) fed low-quality tropical grass hays ad libitum. Diets included supplements based on (Exp1) cottonseed meal (CSM; intake (as fed) 0-10 g/kg liveweight (W).day) and a barley mix (Bar; 0-20 g/kg W.day) and (Exp2) a molasses mix (MUP) and a Bar mix, both fed at 0-20 g/kg W.day. Urea was provided with the Bar mixes and urea/copra meal with the MUP mix. Growth rates of Young steers increased linearly with Bar and MUP supplements but asymptotically with CSM whereas those of Old steers increased asymptotically with all supplement types. With supplement intake expressed on a liveweight basis (g/kg W.day), responses were greater for both steer age groups with CSM compared with Bar (Young, P < 0.001; Old, P < 0.01) and Bar compared with MUP treatments (Young, P < 0.01; Old, P < 0.05). Furthermore, Old steers outperformed their Young counterparts with both CSM (P < 0.05) and Bar (P < 0.001) supplements fed in Exp1 and with Bar and MUP supplements (P < 0.01) fed in Exp2. When supplement intake was expressed in absolute terms (kg/day), growth responses were not different between age groups for different supplements except that Old steers had a higher daily W gain on Bar than their Young counterparts (P < 0.05). Intake of hay (W-corrected) was higher for Young compared with Old steers without supplement but was variably reduced for both steer groups with increasing supplement intake. The results of these experiments have implications for supplement formulation for steers at different stages of maturity grazing low-quality forages. [ABSTRACT FROM AUTHOR]

Response curves were established for different supplements, offered at intakes ranging from 0 to 20 g/kg liveweight (W).day to young Bos indicus crossbred steers fed low-quality Rhodes grass (Chloris gayana) hay ad libitum in two pen experiments. Supplements included protein meals of varying rumen-degradability (cottonseed meal (CSM) or fishmeal), as well as 'energy sources' comprising grains of high and low ruminal starch degradability (barley and sorghum) and a highly fermentable sugar source (molasses), with all diets adjusted for rumen-degradable nitrogen and mineral content. Unsupplemented steers gained 0.08 and 0.15 kg/day, in Experiments 1 and 2, respectively. Growth of steers increased linearly with intake of 'energy source' supplements in increasing order of molasses, sorghum and barley (all differences P < 0.05). Steer growth rate also increased linearly with fishmeal, albeit over a narrow intake range (0-4.1 g/kg W.day), whereas the response with CSM was asymptotic, showing a steep response at low intake before levelling at ~1.2 kg/day. All supplement types were associated with a linear reduction in hay intake by the steers (energy substitution) where the reduction was greater (P < 0.05) for barley and molasses (not different) than for sorghum (P < 0.05), and for fishmeal compared with CSM (P < 0.05). In concurrent metabolism studies with the same rations, organic matter digestibility of the total ration (561-578 g/kg DM, unsupplemented) was increased linearly by barley and molasses (both P < 0.05) but was unaffected by CSM and sorghum supplements. The efficiency of microbial protein synthesis in steers increased linearly, from 91 g microbial crude protein/kg digestible organic matter (unsupplemented), in both molasses and CSM-supplemented steers, with the trend for a higher response to molasses (P = 0.05), and appeared most closely related to digestible organic matter intake. The response curves from these studies provide the practical framework upon which to formulate rations for cattle grazing low-quality forages. [ABSTRACT FROM AUTHOR]

Objective: The objectives were to assess the effects of purified lignin from wheat straw (sodium hydroxide dehydrated lignin; SHDL) on in vitro ruminal fermentation and on the growth performance of feedlot cattle. Methods: In vitro experiments were conducted by incubating a timothy-alfalfa (50:50) forage mixture (48 h) and barley grain (24 h) with 0, 0.25, 0.5, 1.0, and 2.0 mg/mL of rumen fluid (equivalent to 0, 2, 4, 8, and 16 g SHDL/kg diet). Productions of CH4 and total gas, volatile fatty acids, ammonia, dry matter (DM) disappearance (DMD) and digestion of neutral detergent fiber (NDF) or starch were measured. Sixty Hereford-Angus cross weaned steer calves were individually fed a typical barley silage-barley grain based total mixed ration and supplemented with SHDL at 0, 4, 8, and 16 g/kg DM for 70 (growing), 28 (transition), and 121 d (finishing) period. Cattle were slaughtered at the end of the experiment and carcass traits were assessed. Results: With forage, SHDL linearly (p<0.001) reduced 48-h in vitro DMD from 54.9% to 39.2%, NDF disappearance from 34.1% to 18.6% and the acetate: propionate ratio from 2.56 to 2.41, but linearly (p<0.001) increased CH4 production from 9.5 to 12.4 mL/100 mg DMD. With barley grain, SHDL linearly increased (p<0.001) 24-h DMD from74.6% to 84.5%, but linearly (p<0.001) reduced CH4 production from 5.6 to 4.2 mL/100 mg DMD and NH3 accumulation from 9.15 to 4.49 µmol/mL. Supplementation of SHDL did not affect growth, but tended (p = 0.10) to linearly reduce feed intake, and quadratically increased (p = 0.059) feed efficiency during the finishing period. Addition of SHDL also tended (p = 0.098) to linearly increase the saleable meat yield of the carcass from 52.5% to 55.7%. Conclusion: Purified lignin used as feed additive has potential to improve feed efficiency for finishing feedlot cattle and carcass quality. [ABSTRACT FROM AUTHOR]

A survey study was conducted to determine the management practices and constraints faced by beef cattle producers in 200 households in communal areas of Chief Albert Luthuli Municipality in Mpumalanga province. In this context, the results indicated that while 91.5% of farmers practiced continuous breeding in heifers at younger than two years of age, a higher number approximately 68.5% of farmers relied upon neighbours for breeding bulls. Also, calving percentage was between 50% and 70% as reported by 43.5% of farmers whereas 54.5% of farmers reported 50% to 60% weaning percentage. However, 77.5% of the farmers weaned their calves at five to seven months. 100% of farmers freely grazed their beef cattle on the mountainside and over 93.5% of farmers used veld as a source of feed with 82% of farmers supplementing their beef cattle depending on the season. Overall, the main constraints reported by the respondents were disease (26%) and malnutrition (18%) during dry season. In conclusion, the study finds that regular and proper medication in addition to supplementing feeds can assist by reducing mortality rates and enhancing productivity. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to evaluate the effects of feeding condensed distiller's solubles (DS) and crude glycerin alone or in combination on performance of finishing beef cattle and in vitro fermentation. In both experiments, dietary treatments consisted of a steam-flaked corn-based diet with 0% DS or crude glycerin (CON), 10% DS (CDS), 10% crude glycerin (GLY), or a combination of 5% DS and 5% crude glycerin (C+G) included on a DM basis. All treatment diets contained 15% (DM basis) wet distiller's grains plus solubles. In Exp. 1, crossbred steers (n = 256; 322 ± 15 kg initial BW) were used in a randomized complete block finishing trial. Growth performance and gain efficiency were not different (P > 0.10) across all treatments. Treatment had no effect (P > 0.10) on carcass weight, marbling score, yield grade, LM area, or percent grading USDA choice. In Exp. 2, ruminal fluid was collected from 2 ruminally cannulated steers to evaluate in vitro fermentation characteristics. No differences (P = 0.43) were observed for DM disappearance across all treatments. The GLY and C+G treatments had decreased (P = 0.02 and P = 0.05, respectively) NDF disappearance (NDFD), whereas the CDS treatment tended to have decreased (P = 0.06) NDFD compared with CON. Concentrations of NH3 decreased (P < 0.04) with GLY and C+G treatments compared with CON. Total gas production decreased (P < 0.01) for the C+G treatment compared with other treatments. The CDS treatment had increased (P < 0.02) total VFA compared with the CON or C+G treatments. Treatments had no effect (P > 0.17) on concentrations of acetate, propionate, and butyrate, but valerate concentrations were the greatest (P < 0.04) for the CON treatment. Concentrations of isobutyrate increased (P < 0.05) for the CON and C+G treatments compared with the GLY treatment and tended to increase (P < 0.10) compared with the CDS treatment. Including DS or glycerin in the substrates decreased (P < 0.08) isovalerate compared with CON. Feeding additional byproducts such as DS and crude glycerin alone or in combination in a finishing diet did not alter live animal performance or carcass characteristics; however, feeding a combination of the 2 byproducts may alter in vitro fermentation. [ABSTRACT FROM AUTHOR]

The objectives of this research were to test interactions of supplement type, liquid versus dry, and forage type, hay versus corn stover, on digestibility and ruminal metabolism of beef cattle. Ruminally fistulated steers were fed in a replicated 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments: 1) hay with liquid supplement, 2) hay with dry supplement, 3) corn stover with liquid supplement, and 4) corn stover with dry supplement. The liquid supplement was molasses and glycerin based (23.3% CP and 1.63 Mcal/kg NEm) whereas the dry supplement was ground corn based (16.8% CP and 1.81 Mcal/kg NEm). Each period, steers were adapted to diets for 14 d and samples were collected for 8 d. In situ disappearance was determined by a 24-h incubation of Dacron bags, containing soybean hulls, in the rumen. There were no interactions (P ≥ 0.25) of supplement and forage type on DMI, apparent total tract digestibility, or ruminal pH. There was a tendency (P = 0.08) for a forage × supplement type interaction for in situ NDF disappearance (ISNDFD). There were no differences in ISNDFD in steers fed hay, but liquid supplement increased ISNDFD in steers fed corn stover. There were no main effects (P ≥ 0.12) of supplement type on DMI, apparent total tract or in situ digestibility, or ruminal pH. There was a supplement × hour interaction (P = 0.04) for acetate concentrations. Although no effect occurred at 0 h after feeding, at 3 and 6 h after feeding, acetate concentrations were reduced in steers fed liquid supplements when compared with those fed dry supplements. In addition, there was a supplement × hour (P = 0.02) interaction for butyrate concentrations, where at all time points, butyrate concentrations increased (P ≤ 0.01) in steers fed liquid supplements when compared with those fed dry supplements. Steers fed hay had increased DMI (P < 0.01) and apparent total tract NDF digestibility (P = 0.07) when compared with steers fed corn stover, regardless of supplement type. At 0, 1.5, and 18 h after feeding, ruminal pH was greater (P ≤ 0.01) in cattle consuming corn stover when compared with those fed hay, regardless of supplement type. However, steers fed hay had increased (P < 0.01) concentrations of acetate and total VFA compared with steers fed corn stover, regardless of supplement. Feeding liquid supplement increased ISNDFD when steers were fed corn stover; however, these changes were not associated with differences in total tract digestibility. Regardless of forage type fed, the liquid supplement increased ruminal butyrate concentrations. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the use of fecal near-infrared reflectance spectroscopy (NIRS) profiling to predict diet nutritional characteristics and voluntary DMI in beef cattle. Fecal samples were collected for growing cattle across 11 experiments in which individual animal performance and DMI was measured. Dried and ground fecal composite samples collected from each animal were subjected to fecal NIRS analysis by a Foss NIRS 6500 scanning monochromator (Foss, Eden Prairie, MN) at the Grazingland Animal Nutrition Laboratory (Temple, TX). Fecal spectra were then used to develop equations to predict diet composition (trials 1 to 11; n = 408), digestibility (trials 1 to 5; n = 155), and DMI (trials 1 to 11; n = 408). Coefficients of determination for calibration (R²c) and cross-validation (R²cv) for prediction of diet nutritional characteristics were lower for NDF (R²c = 0.85; R²cv = 0.82) than for CP (R²c = 0.90; R²cv = 0.88). For the prediction of DMI, R²c and R²cv ranged from 0.69 and 0.67 for the prediction of trial-average DMI to 0.76 and 0.73 for the prediction of fecal-collection-period DMI. While the R²c and R²cv obtained for the prediction of DMI were lower than those obtained for the prediction of diet composition or digestibility, fecal NIRS prediction equations for DMI were successful in predicting the mean DMI of groups, as no differences were found for the prediction of fecal-collection-period DMI (Diff. = 1.10; P = 0.72) or trial DMI (Diff. = -0.47; P = 0.86). [ABSTRACT FROM AUTHOR]

Two experiments were conducted to evaluate the effects of ractopamine hydrochloride (RAC) dose and duration on growth performance and carcass characteristics of finishing steers. In Exp. 1, 336 crossbred steers (initial BW of RAC feeding = 539 kg [SD 22]) were used in a 2 × 2 factorial arrangement of treatments with one factor being RAC dose (0 or 200 mg/steer daily) and the other factor being RAC duration (28 or 42 d prior to harvest). There were no RAC dose × duration interactions (P ≥ 0.08) for growth performance or carcass characteristics. Feeding 200 mg RAC/steer daily increased (P < 0.01) live final BW by 9.0 kg compared with steers not fed RAC. Carcass-adjusted final BW, ADG, and G:F were greater (P < 0.01) for steers fed 200 mg RAC/d compared with steers not fed RAC. Hot carcass weight was 4.7 kg heavier (P < 0.01) for steers fed 200 mg RAC/d compared with steers not fed RAC. In Exp. 2, crossbred steers (n = 576; experiment initial BW = 408 kg [SD 29]) were used in a randomized block design with a 3 × 3 factorial arrangement of treatments. Factors included RAC dose (0, 300, and 400 mg/steer daily) and RAC duration (14, 28, or 42 d prior to harvest). There was a tendency (P ≤ 0.08) for an interaction of RAC dose × duration for final live BW, DMI, and live G:F; therefore, simple effects are presented. At 28 d, live final BW for steers fed 400 mg RAC/d were heavier (P < 0.01) than for steers fed 0 mg RAC/d. There was a tendency at 28 d for increased live final BW for steers fed RAC at 300 mg/d (P = 0.08) compared with steers fed RAC at 0 mg and for steers fed 400 mg RAC/d compared with steers fed 300 mg RAC/d (P = 0.06). Live final BW was greater (P < 0.01) for steers fed RAC for 42 d at 300 and 400 mg/d compared with steers fed 0 mg; however, live final BW was similar (P = 0.48) between steers fed 300 and 400 mg RAC/d. Despite no RAC dose × duration interaction (P = 0.30) for HCW, simple effects will be presented for consistency. Hot carcass weight was greater for steers fed 300 and 400 mg RAC/d for 28 and 42 d compared with steers fed 0 mg at 28 (P ≤ 0.02) and 42 d (P < 0.01). Feeding 300 mg RAC/d for 28 or 42 d increased HCW by 5.1 and 7.6 kg, respectively, compared with steers fed 0 mg RAC. Additionally, feeding 400 mg RAC/d for 28 or 42 d resulted in increases of 8.9 and 9.4 kg, respectively, in HCW compared with steers fed 0 mg RAC. In conclusion, our results confirm that feeding RAC improves growth performance and carcass weight, with an optimal duration of feeding RAC being 28 d. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the use of 2 byproduct supplements and conserved warm-season forage as winter feeding options for primiparous beef cows. Gestating Angus (n = 48) and Brangus (n = 24) 2-yr-old cows were stratified by BW and breed to 1 of 12 pens. Pens were randomly assigned 1 of 2 supplements, wet brewers' grains (WBG) or dried distillers' grains (DDG). Coastal bermudagrass hay or round bale silage (RBS) was fed free choice (6 pens each) and cows received WBG or DDG supplements at a daily rate of 0.05% BW (DM basis) prorated for feeding 3 d/wk. Total BW and BCS changes did not differ (P = 0.65 and P = 0.93, respectively) between DDG- and WBGsupplemented cows. Total amount of forage DM offered and mean calculated daily forage DM offered did not differ (P = 0.59 and P = 0.20, respectively) between supplement treatments. Estimated daily mean and total supplement DM offered was greater (P < 0.001) for WBG than for DDG treatments. The same 2 supplements and forage sources were used in an unbalanced 6 × 4 design to measure intake, digestibility, and rumen parameters in ruminally fistulated steers. Supplement did not affect forage DMI of hay (P = 0.31) or RBS (P = 0.63). Total DMI was not different (P = 0.37 and P = 0.73) for hay-based and RBS-based diets, respectively. Total tract digestibility tended to be greater (P = 0.06) for DDG than for WBG in hay diets but was not different (P = 0.76) for RBS diets. Daily mean ruminal pH was greater (P = 0.03) for WBG than for DDG when supplemented to hay-based diets. In RBS diets, a supplement × hour interaction (P = 0.05) existed for ruminal pH. Daily mean ruminal ammonia N concentration was greater (P < 0.001) for WBG-supplemented diets compared with DDG-supplemented diets. A supplement × hour interaction existed for ruminal ammonia in hay- (P < 0.001) and RBS- (P = 0.09) based diets. Ruminal pH and ammonia N concentrations stayed in ranges adequate to support ruminal metabolism and cattle performance. Marginal differences in ruminal measures between high-moisture and dry byproduct supplements resulted in no differences in cow performance when offered with hay or high-moisture forage. High-moisture forage sources can be coupled with high-moisture byproduct supplements. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of supplementing energy daily vs. on alternate days at levels that were 1.5 and 2 times the daily amount on DMI, rumen fermentation parameters, and apparent total tract digestibility of beef heifers fed grass hay. Four cannulated Hereford heifers (339 ± 11 kg) were randomly assigned over 4 periods to a 4 × 4 Latin square design. Heifers were fed a coolseason perennial grass (CSPG) hay (10% CP and 42% ADF) and supplemented with a pelleted feed formulated to provide 3.2 Mcal/kg of DE. Treatments consisted of a nonsupplemented control (CON) and 3 supplemented treatments where the supplement was offered daily at 0.6% BW (DLY) or on alternate days at 0.9% BW (LA) and 1.2% BW (HA). Heifers fed DLY had lower (P ≤ 0.04) CSPG hay DMI (7.1 vs. 8.1 kg/d) and mean ruminal pH (6.65 vs. 6.75) and greater (P < 0.01) total short-chain fatty acid (SCFA; 77.1 vs. 69.2 mM) and NH3–N (4.6 vs. 3.4 mg/dL) concentrations in ruminal fluid than CON heifers. The concentration of ruminal NH3–N for LA (5.8 mg/dL) was greater (P < 0.01) than for DLY. Total tract DM digestibility was greater for DLY (52.5%; P ≤ 0.03) than for CON (44.2%) and LA (49.7%), whereas no effects were found (P ≥ 0.11) for DLY vs. HA. When data was analyzed for days when LA and HA were supplemented, hay DMI was greater (P < 0.05) for DLY (7.3 kg/d) vs. HA (6.0 kg/d) but not different (P = 0.16) vs. LA (6.4 kg/d), mean ruminal pH of DLY (6.64) was greater vs. HA (6.59; P = 0.04) and tended to be greater vs. LA (6.60; P < 0.09), and total SCFA concentration of DLY (77.9 mM) was lower (P < 0.01) vs. HA (88.2 mM) and tended (P = 0.08) to be lower vs. LA (84.0 mM). On days when LA and HA were not supplemented, hay DMI was not different (P ≥ 0.48) for DLY vs. LA and HA, mean ruminal pH was greater (P ≤ 0.03) for LA (6.79) and HA (6.85) compared with DLY (6.67), and total SCFA concentration of DLY (76.2 mM) was not different (P = 0.15) vs. LA (67.5 mM) but greater (P = 0.03) vs. HA (62.0 mM). These results show that reducing the amount of supplement fed on alternate supplementation programs from 2 to 1.5 times the amount of daily programs can minimize the negative effects on rumen fermentation and forage DMI. [ABSTRACT FROM AUTHOR]

Objective: Two trials were conducted in order to examine the effects of level of supplemental methionine on productive performance, dietary energetic, plasma amino acid concentration, and digestive function. Methods: Dietary treatments consisted of a steam-flaked corn-based diet containing urea as the only source of supplemental nitrogen supplemented with no supplemental amino acid (control), or control plus 1.01% lysine and 0.032%, 0.064%, 0.096%, or 0.128% methionine. In Trial 1, 150 Holstein steer calves (127±4.9 kg) were utilized to evaluate the influence of treatments on growth-performance, dietary energetic, plasma amino acid concentration during the first 112 days of growing period. During the initial 56-d period calves received the 5 experimental diets. During the subsequent 56-d period all calves were fed the control diet. Results: During the initial 56-d period, methionine supplementation increased (linear effect, p<0.01) plasma methionine. In the presence of supplemental lysine, increases on level of methionine in diet did not affect average daily gain. However, increased gain efficiency (quadratic effect, p = 0.03) and estimated dietary net energy (NE; linear effect, p = 0.05). Estimated metabolizable methionine supply was closely associated (R² = 0.95) with efficiency NE utilization for maintenance and gain. During the subsequent 56-d period, when all calves received the control diet (no amino acid supplementation), plasma amino acid concentrations and growth performance was not different among groups. However, the effects of methionine supplementation during the initial 56-period carried over, so that following a 56-d withdrawal of supplementation, the overall 112-d effects on gain efficiency (quadratic effect, p = 0.05) dietary NE (linear effect, p≤0.05) remained appreciable. In Trial 2, 5 cannulated Holstein steers were used to evaluate treatment effects on characteristics of digestion and amino acid supply to the small intestine. There were no treatment effects on flow of dietary and microbial N to the small intestine. Postruminal N digestion increased (p = 0.04) with increasing level of supplemental methionine. Methionine supplementation linearly increased (p<0.01) duodenal flow of methionine. Likewise, lysine supplementation increased an average of 4.6% (p = 0.04) duodenal flow of lysine. In steers that received nonsupplemented diet, observed intestinal amino acid supply were in good agreement with expected. Conclusion: We conclude that addition of rumen-protected methionine and lysine to diets may enhance gain efficiency and dietary energetics of growing Holstein calves. Observed amino acid supply to the small intestine were in good agreement with expected, supportive of NRC (2000, Level 1). [ABSTRACT FROM AUTHOR]

Objective: Two experiments were performed to evaluate the effects of coated slow-release urea on nutrient digestion, ruminal fermentation, nitrogen utilization, blood glucose and urea concentration (Exp 1), and average daily gain (ADG; Exp 2) of steers. Methods: Exp 1: Eight ruminally fistulated steers [503±28.5 kg body weight (BW)] were distributed into a d 4×4 Latin square design and assigned to treatments: control (CON), feed grade urea (U2), polymer-coated slow-release urea A (SRA2), and polymer-coated slow-release urea B (SRB2). Dietary urea sources were set at 20 g/kg DM. Exp 2: 84 steers (350.5±26.5 kg initial BW) were distributed to treatments: CON, FGU at 10 or 20 g/kg diet DM (U1 and U2, respectively), coated SRA2 at 10 or 20 g/kg diet DM (SRA1 and SRA2, respectively), and coated SRB at 10 or 20 g/kg diet DM (SRB1 and SRB2, respectively). Results: Exp 1: Urea treatments (U2+SRA2+SRB2) decreased (7.4%, p = 0.03) the DM intake and increased (11.4%, p<0.01) crude protein digestibility. Coated slow-release urea (SRA2+SRB2) showed similar nutrient digestibility compwared to feed grade urea (FGU). However, steers fed SRB2 had higher (p = 0.02) DM digestibility compared to those fed SRA2. Urea sources did not affect ruminal fermentation when compared to CON. Although, coated slow-release urea showed lower (p = 0.01) concentration of NH3-N (-10.4%) and acetate to propionate ratio than U2. Coated slow-release urea showed lower (p = 0.02) urinary N and blood urea concentration compared to FGU. Exp 2: Urea sources decreased (p = 0.01) the ADG in relation to CON. Animals fed urea sources at 10 g/kg DM showed higher (12.33%, p = 0.01) ADG compared to those fed urea at 20 g/kg DM. Conclusion: Feeding urea decreased the nutrient intake without largely affected the nutrient digestibility. In addition, polymer-coated slow-release urea sources decreased ruminal ammonia concentration and increased ruminal propionate production. Urea at 20 g/kg DM, regardless of source, decreased ADG compared both to CON and diets with urea at 10 g/kg DM. [ABSTRACT FROM AUTHOR]

Four Japanese Black steers (16 months of age) were assigned to a 4 × 4 Latin square design to investigate the effect of graded levels of sweet-potato condensed distillers solubles (SCDS) in their diets on intake and urinary excretion of minerals. The four diets consisted of 0%, 10%, 20% and 30% (dry matter (DM) basis) SCDS, with SCDS replacing commercial concentrate (CC). Intake of K, Cl, S, P and Mg increased linearly with increasing SCDS content. Urinary pH increased linearly with increasing dietary SCDS content. SCDS feeding increased urinary K concentrations (linear and quadratic effects). Urinary concentrations of Cl increased linearly with increasing SCDS content. In contrast, urinary concentrations of Mg decreased with increasing SCDS content. Feeding of SCDS did not apparently affect urinary NH3,P, Na or Ca concentrations. These results suggest that high SCDS feeding is not a risk for crystallization of minerals leading to the formation of magnesium-phosphate type calculi: although SCDS contains large amounts of P and Mg, high SCDS feeding decreased the Mg concentration and did not affect the P concentration in urine. Additionally, high SCDS feeding had no apparent effects on plasma concentrations of Na, K, Cl, Ca or inorganic P. [ABSTRACT FROM AUTHOR]

The objective of the work was to describe and group units of fattening of commercial Zebu bulls grazing with low supplementation. We studied 44 bovine meat production units belonging to credit and service cooperatives by private farmers, in the municipality Sibanicú, Camagüey province, Cuba. Visits to each of the units were carried out for three years and took the official records of each producer for the variables: the resources, animals, management, production and economics. The major statisticians for this variables were calculated. The average initial weight, final weight, the weight gain and the production by hectare were 202,6; 371,6; 0,501 and 326,2 kg 339,7 days of fattening. Five principal components rotated (Varimax) were obtained. The Principal Analysis Components (PCA) showed a higher than 0,66 Kaiser-Meyer-Olkin coefficient, a coefficient of sphericity of significant Bartlett (P < 0,01) and eigenvalues greater than 1. Pooled units in two groups using two cluster analysis. [ABSTRACT FROM AUTHOR]

Concerns have been raised that in-feed chlortetracycline (CTC) may increase antimicrobial resistance (AMR), specifically tetracycline- resistant (TETr) Escherichia coli and third-generation cephalosporin-resistant (3GCr) E. coli. We evaluated the impact of a 5-day in-feed CTC prophylaxis on animal health, TETr E. coli, and 3GCr E. coli. A control group of cattle (n 150) received no CTC, while a CTC group (n150) received in-feed CTC (10 mg/lb of body weight/day) from the 5th to the 9th day after feedlot arrival. Over 25% (38/150) of the animals in the control group developed illnesses requiring therapeutic treatment with antimicrobials critically important to human medicine. Only two animals (1.3%) in the CTC group required such treatments. Fecal swab and pen surface occurrences of generic E. coli (isolated on media that did not contain antimicrobials of interest and were not isolated based on any specific resistance), TETr E. coli, and 3GCr E. coli were determined on five sampling occasions: arrival at the feedlot, 5 days posttreatment (5 dpt), 27 dpt, 75 dpt, and 117 dpt. On 5 dpt, TETr E. coli concentrations were higher for the CTC group than the control group (P<0.01). On 27 dpt, 75 dpt, and 117 dpt, TETr E. coli concentrations did not differ between groups. 3GCr E. coli occurrences did not differ between control and CTC groups on any sampling occasion. For both groups, generic, TETr, and 3GCr E. coli occurrences were highest on 75 dpt and 117 dpt, suggesting that factors other than in-feed CTC contributed more significantly to antimicrobial-resistant E. coli occurrence. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare voluntary feed intake, nutrient digestibility, and rumen fermentation of Thai native and Thai native x Lowline Angus crossbred beef cattle fed with different diets. Three different diets consisting ofad libitumrice straw (RS),ad libitumRS supplemented with 0.5% body weight (BW) concentrate (RS+C), andad libitumPangola grass hay (PH). The experiment was conducted as 3 × 3 replicated Latin square design with a factorial arrangement of dietary treatment and breed. It was found that Thai native and Thai native x Lowline Angus crossbred beef cattle had comparable roughage intake, BW change, nutrient digestibility, and all parameters from rumen fluid. Cattle fed with different type of feed showed similar roughage intake, BW change, and number of protozoa and fungal zoospore in rumen fluid. However, nutrient intake and digestibility of cattle supplemented with concentrate were higher than those fed the roughage alone. Accordingly, concentration of total volatile fatty acid and proportion of propionic acid in rumen fluid of cattle received concentrate was higher than cattle fed only RS (P < .05) but not for cattle fed with PH. Moreover, the PH-fed group had a higher ammonia concentration in rumen fluid than did the RS-fed group (P < .05). Therefore, the two breeds of beef cattle showed comparable feed response while supplementation of concentrate at 0.50% BW was a useful alternative feeding pattern. [ABSTRACT FROM AUTHOR]