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This experiment evaluated the influence of protein supplementation frequency (SF) and amount offered on intake, nutrient digestibility, and ruminal fermentation by rumen-fistulated beef steers consuming low-quality [2.9% crude protein (CP); dry matter (DM) basis], cool-season forage. Seven Angus × Hereford steers (300 ± 27 kg) fitted with ruminal cannulas were randomly assigned to 1 of 7 treatments in an incomplete 7 × 4 Latin square. Treatments, in a 2 × 3 factorial design plus a non-supplemented control (CON), consisted of 2 levels of supplemental soybean meal, 100% (F) or 50% (H) of the estimated rumen-degradable protein requirement, provided daily (D), once every 5 d (5D), or once every 10 d (10D). Experimental periods were 30 d and dry matter intake (DMI) was measured from days 19 to 28. On days 21 (all supplements provided) and 30 (only daily supplements provided; day immediately prior to supplementation for 5D and 10D treatments) ruminal fluid was collected for ruminal pH, ammonia-N (NH3), volatile fatty acids (VFA), and determination of ruminal fermentation variables. Forage and total DM, organic matter (OM), and nitrogen (N) intake increased with supplementation (P ≤ 0.04). However, a linear effect of SF × amount of supplement interaction was observed for forage and total DM, OM, and N intake (P ≤ 0.04), with each variable decreasing as SF decreased, but the decrease being greater with F vs. H. Apparent total tract DM, OM, and neutral detergent fiber digestibility was not affected by supplementation or amount of supplement provided (P ≥ 0.10). In contrast, N digestibility increased with supplementation and for F vs. H (P < 0.01). Digestibility of DM, OM, and N increased linearly as SF decreased (P ≤ 0.03). When all supplements were provided, ruminal NH3 , total VFA, and molar proportions of all individual VFA increased with supplementation (P ≤ 0.04), whereas acetate:propionate ratio decreased (P < 0.01). When only daily supplements were provided, none of the aforementioned fermentation parameters were affected (P ≥ 0.09). In summary, reducing the amount of supplemental CP provided to ruminants consuming low-quality forages, when supplementation intervals are >5 d, can be a management tool to maintain acceptable levels of DMI, nutrient digestibility, and ruminal fermentation while reducing supplementation cost. [ABSTRACT FROM AUTHOR]

We evaluated the influence of amount and crude protein (CP) supplementation frequency (SF) on nitrogen (N) use by wethers and the performance of late-gestation beef cows. In exp. 1, seven Western whiteface wethers (31.8 ± 1.4 kg) were used in an incomplete 7 × 4 Latin square to evaluate intake and N use. Wethers received one of the seven treatments in a 2 × 3 factorial design containing two levels of supplemental soybean meal offered at a rate of 100% (F) or 50% (H; 50% of F) of the estimated CP requirement daily, once every 5, or once every 10 d, plus a non-supplemented control (CON). Low-quality cool-season forage (4.9 % CP; dry matter [DM] basis) was provided daily for ad libitum intake. Experimental periods lasted 30 d. In exp. 2, 84 Angus × Hereford cows (560 ± 35 kg) were stratified by age, body condition score (BCS), and expected calving date and allocated to 1 of the 21 feedlot pens (three pens per treatment). Pens were randomly assigned to receive the same treatments as in exp. 1 and cows had free access to low-quality cool-season forage (2.9% CP; DM basis). Cow body weight (BW) and BCS were measured every 14 d until calving and within 24 h after calving. In exp. 1, supplementation did not alter total DM and organic matter (OM) intake (P ≥ 0.26), but both parameters linearly decreased as SF decreased (P = 0.02). Supplementation increased DM, OM, and neutral detergent fiber (NDF) digestibility (P ≤ 0.02). Additionally, F feeding linearly increased DM, OM, and NDF digestibility as SF decreased (P ≤ 0.04). Digestibility of N, N balance, and digested N retained were greater with supplementation (P < 0.01), and N digestibility linearly increased as SF decreased (P = 0.01). Mean plasma urea-N concentration was not only greater (P < 0.01) for supplemented vs. CON wethers but also greater (P = 0.03) for F vs. H. In exp. 2, pre-calving BCS change was greater (P = 0.03) for supplemented cows. A linear effect of SF × supplementation rate for pre-calving BCS change was noted (P = 0.05), as F-supplemented cows lost more BCS compared with H as SF decreased. When considering supplementation intervals greater than 5 d, reducing the quantity of supplement provided, compared with daily supplementation, may be a feasible management strategy to maintain acceptable nutrient use and animal performance while reducing supplement and labor costs. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of gradual reduction in frequency of energy supplementation following vaccination on growth and measurements of innate and humoral immunity of beef steers. At 14-d postweaning (d 0), Angus steers (n = 42; 200 ± 5 kg of BW; 175 ± 4 d of age) were stratified by BW and age, and randomly assigned into 1 of 14 drylot pens (three steers/pen). From d 0 to 42, steers were provided ad libitum ground tall fescue hay (57% TDN, 13% CP of DM basis) and supplemented with concentrate at 1% of BW (50:50 soybean hulls and corn gluten feed; 71% TDN, 15% CP of DM basis). Treatments were randomly assigned to pens, and consisted of similar weekly concentrate DM supplementation (1% of BW multiplied by 7 d) that was divided and offered daily from d 0 to 42 (7X; 4 pens), 3 times weekly from d 0 to 42 (3X; Monday, Wednesday, and Friday; 5 pens), or daily from d 0 to 15 and then 3 times weekly from d 16 to 42 (7-3X; 5 pens). Steers were vaccinated against infectious bovine rhinotracheitis (IBR), bovine viral diarrhea virus (BVDV), parainfluenza-3 (PI-3), Mannheimia haemolytica, and Clostridium on d 0 and 15. Individual shrunk BW was collected on d 0 and 42, following 12 h of feed and water withdrawal. Blood samples were collected via jugular venipuncture 4 h after concentrate supplementation on d 0, 1, 2, 3, 7, 15, 16, 17, 18, 22, and 42. Mean BW, ADG, G:F, hay DMI, and total DMI over the 42-d period did not differ among treatments (P ≥ 0.26). Plasma concentrations of cortisol and mean serum BVDV-1a titers also did not differ among treatments (P ≥ 0.35), but overall plasma haptoglobin concentrations were greater for 3X vs. 7-3X and 7X steers (P ≤ 0.05; 0.44, 0.37, and 0.33 ± 0.026 mg/mL, respectively). Also, 3X steers had less mean serum IBR titers (P ≤ 0.05; 0.29 vs. 0.88 and 0.79 ± 0.179 log2, respectively) and less seroconversion to PI-3 virus on d 15 than 7-3X and 7X steers (P ≤ 0.05; 36.0 vs. 76.6 and 57.8 ± 8.24%, respectively). In summary, a gradual reduction in frequency of energy supplementation during a 42-d preconditioning period did not negatively impact growth, but alleviated indices of inflammation and prevented reductions in vaccine response against BVDV-1a and PI-3 viruses compared to steers offered concentrate 3 times weekly during the entire study. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine if supplementation frequency of rumen-protected fat (RPF) influences circulating serum concentrations of fatty acids (FA), NEFA, and urea nitrogen in beef heifers and lactating cows. In Exp. 1, 12 early gestation beef heifers were supplemented 0.5 kg of corn gluten feed (CGF) daily during a 2-wk adaptation period. During the last 3 d of adaptation, blood samples were collected immediately before supplementation and then 8 and 16 h postsupplementation daily. Each heifer was then randomly assigned to 1 of 3 supplementation frequency treatments of RPF (3, 5, or 7 d/wk) for 3 wk in a 3 x 3 Latin square design with 3 periods (4 heifers per treatment per period), with each treatment receiving the same amount of RPF and CGF per wk (1.0 and 2.7 kg as fed, respectively). Blood samples were collected during the final 3 d of each supplementation period as described in the adaptation period. In Exp. 2, 18 Angus crossbred cows in early lactation were supplemented with 4.54 kg (as fed) of CGF weekly either at 3, 5, or 7 d/wk during a 2-wk adaptation period. Blood samples were collected during the last 3 d of adaptation as in Exp. 1. For the subsequent 3 wk, RPF (530, 318, and 227 g/d when supplemented) was added to the CGF supplement so that each supplementation frequency received 1.59 kg as fed/wk of RPF. Blood samples were collected during the last 3 d of supplementation as in Exp. 1. Serum FA profiles on a random subsample of 9 heifers in Exp. 1 and all animals in Exp. 2 were determined via gas chromatograph (GC), and values were analyzed using the MIXED procedure of SAS. In Exp. 1, there were no differences (P ≥ 0.53) in serum FA profile across supplementation frequencies. There was a decrease in serum 18:2, 18:1 trans-9 and total FA during the sampling time (time effect, P < 0.02). In Exp. 2, there was treatment x time effect (P ≤ 0.001) for both 18:2 and total FA measured. The 7 d/wk frequency had a greater concentration of C18:2 and total FA at 8 h of the sampling period when compared to the other 2 frequencies. These results demonstrate that supplementation of RPF at 3, 5 or 7 d/wk resulted in no changes in serum FA profiles in growing heifers. In early lactating beef cows, there were minor time point changes in serum FA due to supplementation frequency; however, the vast majority of time points were not different, indicating no substantial changes in serum FA profiles. [ABSTRACT FROM AUTHOR]

Dois experimentos foram conduzidos com o objetivo de avaliar os efeitos da frequência de suplementação com duas fontes proteicas sobre o desempenho produtivo e econômico e o consumo e a digestibilidade dos nutrientes em bovinos em pastejo sob suplementação durante o período seco do ano. Foram utilizados 20 animais anelorados, não-castrados com 10 meses de idade e peso médio inicial de 208,43 kg, distribuídos em quatro piquetes de capim-marandu (Brachiaria brizantha, cv. Marandu), cada um com 1,6 ha. Ambos os experimentos foram estruturados em arranjo fatorial 2 × 2, com dois suplementos (com farelo de soja e com farelo de algodão de alta energia) e duas frequências de suplementação (diariamente ou três vezes por semana). Não houve interação fontes proteicas × frequências de suplementação para nenhuma das características de desempenho produtivo e econômico. As fontes proteicas não influenciaram o ganho médio diário, mas a frequência de fornecimento afetou o desempenho, que foi melhor nos animais sob suplementação três vezes/semana (0,670 kg/dia). O maior retorno econômico foi obtido com a oferta do suplemento com farelo de algodão três vezes por semana. A frequência de suplementação afetou o consumo de nutrientes, enquanto a fonte proteica do suplemento teve efeito somente sobre o consumo de extrato etéreo, que foi maior nos animais que consumiram o suplemento com farelo de algodão. O suplemento com farelo de algodão alta energia proporcionou maior digestibilidade da proteína bruta da dieta. O fornecimento de suplemento três vezes por semana, além de reduzir os custos da suplementação, possibilita desempenho superior ao obtido com a suplementação diária. A utilização do farelo de algodão de alta energia em suplementos múltiplos em substituição ao farelo de soja é satisfatória, principalmente do ponto de vista econômico.Two experiments were carried out with the objective of evaluating the effects of the frequency of supplementation with two proteins sources on productive and economical performance (experiment 1) and the nutrients digestibility of steers in supplemented pasture during the dry season over a year. It was used twenty weaned zebu calves at the age of 10 months and initial live weight (LW) of 208.43 kg, distributed in four paddocks of Brachiaria brizantha cv. Marandu, each one with 1.6 ha. Both experiments were structured in 2 × 2 factorial arrangement with two supplements (with soybean meal and high energy cottonseed meal). There was no protein sources × supplementation frequency interaction for any of the economical and productive performance traits. The protein sources didn't affect the daily average gain, but the frequency of supply affected performance, which was better in the animals under supplementation at three times a week (0.670 kg /day). The highest economic return was obtained with the offer of supplement with cottonseed meal three times a week. The frequency of supplementation affect the nutrients intake, while the protein source of the supplement had effect only on the ethereal extract intake, which was higher in the animals that consumed the supplement with cottonseed meal. The supplement with high energy cottonseed meal provided higher digestibility of diet crude protein. The supply of supplement three times a week, not only reduces the costs of supplementation, but it possibilities a higher performance than the one obtained with daily supplementation. The use of higher energy cottonseed meal in multiple supplements replacing soybean meal is satisfactory mainly under economical point of view.

Este trabalho foi realizado com o objetivo de avaliar o ganho de peso de bovinos mantidos em pastagens de Brachiaria brizantha cv. Marandu submetidos a três estratégias de suplementação no período das águas e da seca de 2003 e águas de 2004. Os tratamentos consistiram da suplementação diária (SD), em dias alternados (DA) e de segunda à sexta-feira (SF). Foram utilizados 24 bovinos mestiços com peso inicial de 230 kg. Os animais foram pesados individualmente sem jejum, em intervalos de 28 dias. O delineamento adotado foi o inteiramente casualizado, com três tratamentos e oito repetições. Não houve diferença no ganho de peso dos animais, sendo obtidos valores médios de 0,76; 0,71 e 0,74 kg/dia no período das águas de 2003, de 0,57; 0,51 e 0,54 kg/dia na seca do mesmo ano e de 0,61; 0,62 e 0,57 kg/dia no período das águas de 2004 nos tratamentos SD, DA e SF, respectivamente. A redução na freqüência de suplementação pode representar uma opção para o produtor visando à redução dos custos do fornecimento da alimentação, pois permite maior racionalização da mão-de-obra na propriedade e não afeta o desempenho animal.The objective of this study was to evaluate weight gain of beef steers grazing Brachiaria brizantha cv. Marandu and receiving one out of three different supplementation strategies during the rainy season of 2003 and the dry and rainy seasons of 2004. Twenty-four crossbreed steers averaging 230 kg of initial body weight were assigned to one of the following supplementation strategies: daily supplementation (DS), supplementation in alternated days (AD), or supplementation from Monday to Friday (MF) in a completely randomized design (8 replicates/treatment). Animals were individually weighted with no fasting every 28 days. There were no differences in weight gain among the different supplementation strategies averaging 0.76, 0.74, and 0.71 kg/day during the rainy season of 2003; 0.61, 0.62, and 0.57 kg/day during the dry season of 2004; and 0.57, 0.54, and 0.51 kg/day during the rainy season of 2004, respectively, for DS, AD and MF treatments. It can be concluded that reducing supplementation frequency may decrease feeding and labor costs with no negative impact on animal performance.

The aim of the present study was to evaluate the different supplementation strategies for finishing Nellore beef cattle on pastures of Tanzania guinea grass ( Panicum maximum Jacq. 'Tanzania'). The experiment was performed in a 12 ha area divided into 12 paddocks of 1 ha each. Forty-eight, 2-year-old, non-castrated Nellore cattle with an initial body weight (BW) of 384 kg (SEM = 21) were used in this study. The following supplementation strategies were evaluated: (1) mineral supplement supplied once per week (MS), (2) energy and protein supplement with intake regulator (2 g/kg BW) supplied once per week (EPS1), (3) energy and protein supplement (7 g/kg BW) supplied daily (EPS2), and (4) energy and protein supplement (7 g/kg BW) supplied three times per week (EPS3). The average daily gain (ADG) of animals receiving EPS3 was 0.177 kg/day higher than those receiving EPS1 ( p < 0.01), 0.233 kg/day higher than the MS group, and not significantly different from EPS2. Animals in MS and EPS1 groups exhibited the lowest ADG. The ADG was not significantly different between EPS1 and EPS2 animals, but was 0.203 kg/day higher for EPS2 animals than for MS. Animals receiving only mineral supplementation spent more time grazing than the other supplementation groups tested ( p < 0.01). We therefore conclude that Tanzania guinea grass is nutritionally limited and can be amended using supplements, thereby increasing animal performance. Animal performance was higher with increased protein and energy supplementation (7 g/kg BW), independent of the frequency with which supplements were administered. [ABSTRACT FROM AUTHOR]

This study evaluated growth and measurements of innate and humoral immunity of preconditioning beef heifers supplemented with wet brewers grains (WBG) at 2 supplementation rates and frequencies. At 14 d after weaning (d 0), Angus heifers (n = 36; 213 ± 2 kg BW and 254 ± 7 d of age) were stratified by BW and age and randomly assigned to 1 of 12 drylot pens (3 heifers/pen). Treatments were randomly assigned to pens, in a 2 × 2 factorial design, and consisted of heifers provided ground tall fescue hay ad libitum (55% TDN and 12% CP of DM) and supplemented with WBG (75% TDN and 36% CP of DM) either daily (7X) or 3 times weekly (3X; Monday, Wednesday, and Friday) at 0.5 or 1.0% of BW (DM basis) for 42 d. Heifers were vaccinated against infectious bovine rhinotracheitis (IBR), bovine viral diarrhea virus (BVDV), Mannheimia haemolytica, and Clostridium on d 14 and 28. Individual BW was measured before feeding on d 0 and 42 following 12 h of feed and water withdrawal. Blood samples were collected via jugular venipuncture 4 h after WBG supplementation on d 14, 15, 16, 17, 21, 28, 29, 30, 31, 35, and 42. Heifers fed WBG 3X had less hay DMI (2.6 ± 0.16 vs. 3.2 ± 0.16 kg/d; P < 0.0001) but greater total DMI (5.6 ± 0.16 vs. 3.8 ± 0.16 kg/d; P < 0.0001) than 7X heifers on days that all heifers received WBG supplementation. However, overall hay and total DMI was not affected (P = 0.40) by supplementation frequency. Therefore, ADG, BW, and G:F from d 0 to 42 did not differ among treatments (P ≥ 0.29). Plasma concentrations of haptoglobin on d 15 and cortisol on d 14 were greater for 3X heifers vs. 7X heifers (P ≤ 0.04). Heifers fed WBG at 0.5% of BW tended to have greater plasma cortisol concentrations on d 15, 17, and 35 (P ≤ 0.09) than heifers fed at 1.0% of BW. Serum BVDV-1a titers were greater (P = 0.04) for 7X heifers vs. 3X heifers on d 42 (4.2 ± 0.28 vs. 3.3 ± 0.28 log2), whereas serum titers against BVDV- 2 and IBR were greater for heifers fed WBG at 1.0% of BW vs. heifers fed WBG at 0.5% of BW (7.6 vs. 6.7 and 3.3 vs. 2.8 ± 0.19 log2, respectively). In summary, decreasing WBG supplementation frequency (7 vs. 3 times weekly) or rate (1.0 vs. 0.5% of BW) for recently weaned beef heifers did not affect growth but decreased vaccine-induced antibody production against pathogens associated with bovine respiratory disease during a 42-d preconditioning period. [ABSTRACT FROM AUTHOR]

Our objectives were to evaluate postnatal growth and measurements of innate and humoral immunity of beef calves born to dams fed wet brewers grains (WBG) daily or 3 times weekly during late gestation. On d 0 (approximately 60 d before calving), 28 multiparous, spring-calving Angus cows (BW = 578 ± 19 kg; age = 4.7 ± 0.65 yr; BCS = 7.0 ± 0.18) were stratified by sire, age, BW, and BCS and then randomly allocated into 1 of 14 drylot pens (2 cows/pen; 18 by 3 m; 27 m2/cow). Cows were offered ground tall fescue hay ad libitum and received similar weekly WBG supplementation (DMI = 0.5% of BW multiplied by 7 d). Treatments were randomly assigned to pens (7 pens/treatment) and consisted of cows receiving WBG supplementation daily (S7; weekly DMI of WBG divided by 7 d) or 3 times weekly (S3; weekly DMI of WBG divided by 3 d; Mondays, Wednesdays, and Fridays) from d 0 until calving. Cow-calf pairs were managed as a single group on tall fescue pastures from calving to weaning (d 226). Calves were immediately submitted to a preconditioning period from d 226 to 266 and vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea virus, Mannheimia haemolytica, and Clostridium on d 231 and 245. Decreasing the frequency of WBG supplementation did not impact (P ≥ 0.21) precalving intake of total DM, CP, and TDN; BW and BCS change; overall plasma cortisol concentrations; and postcalving growth and pregnancy rate of cows. Overall plasma concentrations of glucose and insulin did not differ (P ≥ 0.28) between S3 and S7 cows, whereas S3 cows had greater (P = 0.002) plasma glucose concentrations and tended (P = 0.06) to have greater plasma insulin concentrations on days they were not fed WBG vs. days of WBG supplementation. Calf plasma concentrations of haptoglobin and cortisol at birth but not serum IgG (P = 0.63) tended (P = 0.10) to be greater for S3 vs. S7 calves. However, additional calf growth and immunity variables obtained during preand postweaning phases did not differ between S3 and S7 calves (P ≥ 0.21). Hence, decreasing the frequency of WBG supplementation during late gestation caused oscillations on precalving plasma glucose and insulin concentrations but did not affect plasma cortisol concentrations, growth, and pregnancy rate of cows. Also, reduced frequency of WBG supplementation during late gestation did not have carryover effects on postnatal calf growth and immunity. [ABSTRACT FROM AUTHOR]

We evaluated the effects of frequency of energy supplementation on growth and measurements of innate and humoral immune responses of preconditioning beef steers following vaccination. Angus steers (n = 24; 221 ± 6.3 kg; 177 ± 4 d of age) were weaned on d -7 and kept in a single drylot pen with free access to tall fescue hay and concentrate DMI at 0.5% of BW (50:50 mix of soyhulls and corn gluten pellets; DM basis) from d -7 to 0. On d 0, steers were stratified by BW and age and randomly assigned to 1 of 8 feedlot pens (3 steers/pen). Treatments were randomly assigned to pens (4 pens/treatment) and consisted of steers provided daily free access to ground tall fescue hay and similar weekly concentrate DMI (1% of BW times 7 d), which was divided and offered either daily (S7) or 3 times weekly (S3; Monday, Wednesday, and Friday) from d 0 to 42. Individual BW was measured before feeding on d 0 and 42, after 12 h of feed and water withdrawal. Steers were vaccinated against infectious bovine rhinotracheitis, bovine viral diarrhea virus (BVDV), Mannheimia haemolytica, and clostridium on d 7 and 21. Blood samples were collected from the jugular vein on d -7 and 4 h after concentrate supplementation on d 0, 7, 8, 9, 10, 14, 21, 22, 23, 24, 28, 35, and 42. Steers offered concentrate daily had greater (P = 0.02) BW on d 42, overall ADG, and total DMI, but similar (P = 0.14) G:F, than S3 steers. On days that S7 and S3 steers were offered concentrate, total DMI was greater and hay DMI was less for S3 vs. S7 steers (P = 0.05). On days that only S7 steers were supplemented, hay DMI was greater, but total DMI was less for S3 vs. S7 steers (P = 0.05). Mean CP and NEg intake were greater (P = 0.03) for S7 vs. S3 steers. Plasma cortisol concentrations on d 7 and 28, and mean plasma haptoglobin concentrations, but not liver mRNA expression of haptoglobin (P = 0.75), were greater for S3 vs. S7 steers (P = 0.03). Plasma IGF-1 concentrations on d 0 and urea nitrogen on d 1 and 3, relative to vaccination, were greater for S7 vs. S3 steers (P = 0.008). Positive seroconversion to BVDV-1b on d 42 and mean serum BVDV-1b titers were greater for S7 vs. S3 steers (P = 0.05). In summary, decreasing the frequency of concentrate supplementation from daily to three times weekly, during a 42-d preconditioning period, decreased growth performance, increased plasma concentrations of haptoglobin and cortisol, and decreased vaccine-induced antibody production against BVDV-1b of beef steers. [ABSTRACT FROM AUTHOR]

Four ruminally and duodenally cannulated Holstein steers (BW = 449 ± 7.3 kg) were used to examine the effects of feeding either dried distiller's grains plus solubles (DG) or grass hay on alternate days (every other day) on intake, ruminal fermentation and passage rates, and serum NEFA in forage-fed steers. Steers were assigned to 1 of 4 dietary treatments in a 4 × 4 Latin square: 1) only hay (CON), 2) hay and 0.4% of BW as DG DM daily (DG7), 3) hay daily and 0.8% BW DG every other day (DG2), and 4) alternate day feeding of hay and 0.8% of BW as DG (DGA). Treatment periods consisted of 13 d of adaptation and 8 d of collecting digesta and blood. Over the entire collection period, DMI was decreased (P = 0.004) for DGA compared with other treatments (13.0 ± 0.8, 12.7 ± 0.8, 13.3 ± 0.8, and 10.9 ± 0.8 kg/d for CON, DG7, DG2, and DGA, respectively). Immediately after feeding on days supplement was fed to DG2 and DGA (supplemented days [SUP]), ruminal pH of DGA was less than other treatments but by the end of the day was greater than other treatments (treatment × time, P < 0.001). At feeding time on nonsupplemented days (NSUP), ruminal pH of DGA steers was greater than other treatments but was similar (treatment × time, P < 0.001) to DG2 and CON by 5 h after feeding. Total concentrations of VFA were similar (P = 0.09) among treatments on SUP; however, on NSUP, total VFA concentrations were least in DGA from feeding until 4 h after feeding (treatment × time, P = 0.02). No differences (P = 0.06) were observed among treatments for apparent ruminal, total intestinal, and total tract DM, OM, or CP digestibility. There were no differences (P = 0.36) in serum NEFA among treatments on SUP; however, on NSUP, steers fed DGA (209.5 ± 12.7 mM) had greater (P < 0.01) NEFA compared with other treatments (84.4 ± 12.7, 88.0 ± 12.7, and 77.7 ± 12.7 mM for CON, DG7, and DG2, respectively). The DGA feeding strategy influenced DMI and ruminal kinetics and circulating NEFA without impacting total tract digestibility. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to determine if frequency of protein supplementation impacts physiological responses associated with reproduction in beef cows. Fourteen nonpregnant, nonlactating beef cows were ranked by age and BW and allocated to 3 groups. Groups were assigned to a 3 × 3 Latin square design, containing 3 periods of 21 d and the following treatments: 1) soybean meal supplementation daily (D), 2) soybean meal supplementation 3 times/week (3WK), and 3) soybean meal supplementation once/week (1WK). Within each period, cows were assigned to an estrus synchronization protocol: 100 μg of GnRH + controlled internal drug release device (CIDR) containing 1.38 g of progesterone (P4) on d 1, 25 mg of PGF2α on d 8, and CIDR removal + 100 μg of GnRH on d 11. Grassseed straw was offered for ad libitum consumption. Soybean meal was individually supplemented at a daily rate of 1 kg/cow (as-fed basis). Moreover, 3WK was supplemented on d 0, 2, 4, 7, 9, 11, 14, 16, and 18 whereas 1WK was supplemented on d 4, 11, and 18. Blood samples were collected from 0 (before) to 72 h after supplementation on d 11 and 18 and analyzed for plasma urea-N (PUN). Samples collected from 0 to 12 h were also analyzed for plasma glucose, insulin, and P4 (d 18 only). Uterine flushing fluid was collected concurrently with blood sampling at 28 h for pH evaluation. Liver biopsies were performed concurrently with blood sampling at 0, 4, and 28 h and analyzed for mRNA expression of carbamoyl phosphate synthetase I (CPS-I; h 28) and CYP2C19 and CYP3A4 (h 0 and 4 on d 18). Plasma urea-N concentrations were greater (P < 0.01) for 1WK vs. 3WK from 20 to 72 h and greater (P < 0.01) for 1WK vs. D from 16 to 48 h and at 72 h after supplementation (treatment × hour interaction, P < 0.01). Moreover, PUN concentrations peaked at 28 h after supplementation for 3WK and 1WK (P < 0.01) and were greater (P < 0.01) at this time for 1WK vs. 3WK and D and for 3WK vs. D. Expression of CPS-I was greater (P < 0.01) for 1WK vs. D and 3WK. Uterine flushing pH tended (P ≤ 0.10) to be greater for 1WK vs. 3WK and D. No treatment effects were detected (P ≥ 0.15) on expression of CYP2C19 and CYP3A4, plasma glucose, and P4 concentrations, whereas plasma insulin concentrations were greater (P ≤ 0.03) in D and 3WK vs. 1WK. Hence, decreasing frequency of protein supplementation did not reduce uterine flushing pH or plasma P4 concentrations, which are known to impact reproduction in beef cows. [ABSTRACT FROM AUTHOR]

Forty-six nonlactating beef cows were used to examine effects of dried distiller's grains plus solubles (DG) supplementation strategies to cows fed grass hay during mid- to late gestation on BW, ultra-sound body composition characteristics, concentrations of serum NEFA and urea, feeding behavior, and calf birth weight. Cows were assigned to dietary treatments in a completely randomized design: 1) control, where hay was fed each day of the week (CON), 2) both hay and DG fed daily during the week (DG7), 3) hay fed daily but DG fed 3 d of the week (DG3), and 4) hay fed 4 d of the week alternating with DG fed on the remaining 3 d (DGA). Hay was offered ad libitum on days it was fed. The DG were fed at 0.40% of BW when offered daily and 0.93% of BW when offered 3 d per week (Monday, Wednesday, and Friday). Feed intake was monitored continuously over the 84-d feeding period. Hay intake and total DMI were reduced (P < 0.05) in DGA compared with DG7 and DG3. Gain and G:F were decreased (P < 0.05) for CON compared with other treatments. No differences (P > 0.05) were observed among treatments for change in BCS, intramuscular fat, rib fat, or rump fat from d 1 to 84. On a day when DG7, DG3, and DGA all received DG (Friday), DGA had reduced (P < 0.05) concentrations of urea compared with DG3 and DG7. On a day when only DG7 received DG (Saturday), urea was greater (P <0.01) for DG3 and DGA compared with DG7, and concentrations of NEFA were greater (P <0.01) in CON and DGA compared with DG7. On the second consecutive day when only DG7 received DG (Sunday), concentrations of NEFA were less (P < 0.001) for DG7 compared with other treatments. On days when all cows received hay, DGA spent more time eating (P < 0.05) compared with DG7 and DG3. Cows fed DGA had greater (P < 0.05) hay intake per meal and time per meal compared with other treatments. On days when DG7, DG3, and DGA all received DG, cows in the DG3 and DGA treatments had greater (P < 0.05) number of DG meals, time spent eating, intake per meal, and time per meal but a slower (P < 0.05) rate of DG intake compared with DG7. No differences (P > 0.05) were observed in calf birth weights among treatments. The alternateday feeding strategy reduced hay and total intake, altered concentrations of serum urea and NEFA, and altered feeding behavior compared with other supplementation methods. [ABSTRACT FROM AUTHOR]

Reducing supplementation frequency in calf growing programs can reduce labor and equipment operation costs. However, little is understood about the metabolic response of ruminants to large fluctuations in nutrient intake. Eighteen Angus or Angus x Simmental cross steers (287 ± 20 kg and 310 ± 3.6 d of age) were individually fed 1 of 3 dietary treatments using Calan gates. Dietary treatments consisted of ad libitum hay and no supplement (NS), ad libitum hay and 1% BW (asfed basis) of supplement daily (DS), or ad libitum hay and 2% BW (as-fed basis) of supplement every other day (SA). The supplement was 90% DM and contained (as-fed basis) 47% com gluten feed, 47% soybean hulls, 2% feed grade limestone, and 4% molasses. Hay intake and ADG was measured over a 52-d period. Steers were then moved to individual tie stalls. Steers were fed at 0800 h and blood samples were collected every hour from 0600 to 1400 h and at 1800,2200, and 0200 h over a 2-d period. Gains were increased (P < 0.01) by supplementation but did not differ (P = 0.68) due to supplementation frequency. Average daily gain was 0.45, 0.90, and 0.87 kg hd-1 -d-1 (SEM ± 0.05) for steers NS, DS, and SA, respectively. Across the 2-d supplementation cycle area under the concentration time curve (AUC) for plasma glucose was increased (P < 0.01) by supplementation but did not differ (P = 0.41 ) due to supplementation frequency. The AUC for plasma insulin was increased by supplementation (P < 0.01) but did not differ (P = 0.67) due to supplementation frequency. Plasma IGF-1 was increased (P = 0.01) by supplementation and was greater (P = 0.04) for steers supplemented SA than DS. Gains of steers supplemented with a soybean hull and corn gluten feed blend on alternate days did not differ from those supplemented daily suggesting the steers were able to efficiently utilize large boluses of nutrients fed every other day. The effect of less frequent supplementation on IGF-1 deserves further examination as this hormone has been shown to increase protein synthesis. [ABSTRACT FROM AUTHOR]

Five ruminally cannulated steers (initial BW=464±26kg) consuming low-quality forage (5% CP; 78% NDF; DM basis) were used in an incomplete 5×4 Latin square with four 18-d periods to determine the influence of supplemental N source and supplementation frequency (SF) on ruminal fermentation dynamics. Treatments, arranged as a 2×2 factorial with a negative control, consisted of urea or soybean meal (SBM) supplements offered daily (D) or alternate days (2D) plus an unsupplemented treatment (CON). Urea supplements were provided to meet 100% of the degradable intake protein requirement while SBM supplements were provided on an isonitrogenous basis. All supplemented treatments received an equal quantity of supplemental N over a 2-d period. Ruminal indigestible acid detergent fiber (IADF) passage rate was increased with supplementation (P≤0.03) on the days when D and 2D supplements were provided, as well as when only D supplements were provided. In contrast, ruminal liquid fill and dilution rate were not affected by supplementation, N source, or SF on the days when D and 2D supplements were provided (P≥0.24). However, when only D supplements were offered, ruminal liquid dilution rate was greater (P=0.03) for SBM supplemented steers compared with cohorts receiving supplemental urea, whereas ruminal liquid fill was greater (P=0.03) for steers fed urea supplements. Nitrogen supplementation increased (P<0.01) ruminal NH3–N by 122% and 70%, compared with the CON, on the days when both D and 2D supplements were provided and when only D supplements were provided, respectively. We noted a N source×SF interaction for ruminal NH3–N on the days when D and 2D supplements were provided (P=0.02), as well as when only D supplements were provided (P<0.01). On the days when D and 2D supplements were provided, urea increased NH3–N by 61% (2.93 vs. 4.73mM for D and 2D, respectively), whereas the increase in NH3–N with SBM was only 15% (2.23 vs. 2.58mM for D and 2D, respectively). However, when only D supplements were provided, NH3–N was almost 36% less for the 2D compared with the D urea treatment (2.76 vs. 1.81mM, respectively), whereas an 11% increase was noted for SBM 2D compared with SBM D (1.99 vs. 1.79mM, respectively). Total concentration of VFA was increased on the days when both D and 2D supplements were provided (P=0.03), but not influenced by treatments on the days when only D supplements were provided (P≥0.50). In summary, providing a urea-based supplement, as infrequently as every-other-day, was an effective alternative to a SBM-based supplement in maintaining acceptable ruminal fermentation of steers consuming low-quality, cool-season forage. [ABSTRACT FROM AUTHOR]

Reducing the frequency of supplementation to beef cattle would reduce labor and vehicle maintenance costs and could have the potential to increase profits if performance is not negatively affected. Six ruminally cannulated beef steers (362±18 kg of BW) were used in a replicated 3 × 3 Latin square design to determine the effect of supplementation frequency (daily or on alternate days) on digestion and ruminal parameters when feeding medium-quality hay and supplementing with a mixture of soybean hulls and corn gluten feed. Dietary treatments consisted of ad libitum fescue hay (8.8% CP and 34.8% ADF) that was supplemented at 1% of BW daily (SD), supplemented at 2% of BW on alternate days (SA), or not supplemented (NS). The supplement (14.6% CP and 29.8% ADF) contained 47% soybean hull pellets, 47% corn gluten feed pellets, 2% feed grade limestone, and 4% molasses (as fed). Each period consisted of a 12-d adaptation phase followed by 6 d of total fecal, urine, and ort collection. All supplement offered was consumed within 2 h. Ruminal fluid was collected every 4 h for 2 d. Hay intake was reduced (P < 0.01) for SD and further reduced (P < 0.01) for SA. Hay intake was 1.54, 1.19, and 1.02% of BW (SEM ± 0.036) for NS, SD, and SA, respectively. There was a treatment (P < 0.01) × day interaction for mean ruminal pH. On the day of supplementation, ruminal pH for SA (6.13) was lower (P < 0.01) than those for both SD (6.29) and NS (6.52). However, on the day the SA treatment did not receive supplement, ruminal pH of SA (6.53) did not differ (P = 0.87) from ruminal pH of NS and was greater (P < 0.01) than that of SD. Ruminal pH of SD was lower (P < 0.01) than that of NS. Diet DM digestibility was increased (P < 0.01) by supplementation but did not differ (P = 0.58) because of frequency. Dry matter digestibility was 57.9, 64.1, and 64.6% (SEM ± 0.65) for NS, SD, and SA, respectively. The amount of N retained did not differ (P = 0.47) because of frequency (24.9 ± 5.61 and 22.0 #x00B1; 5.50 g/d for SD and SA, respectively) and was greater (P < 0.01) for the supplemented treatments than for NS (4.2 ± 3.30 g/d). When supplementing a blend of soybean hulls and corn gluten feed, producers can reduce the frequency of supplementation to every other day without reducing digestibility or N retention. [ABSTRACT FROM AUTHOR]

Abstract: Feeding supplements less frequently can reduce labor costs and increase profitability. However reducing the frequency of delivery of grain based supplements can negatively affect fiber digestion in the rumen because more grain must be fed per feeding potentially causing decreased ruminal pH and/or an insufficiency of ruminal nitrogen. Using supplements that have a moderate crude protein (CP) level, and that are low in starch, might alleviate negative effects on fiber digestion and therefore decrease negative effects associated with supplementing energy supplements less frequently. Corn gluten feed and soybean hulls are high in metabolizable energy but low in fat and starch, and corn gluten feed is also a good source of ruminally degradable CP. The objective of this study was to determine effects of reducing supplementation frequency during a weekly cycle on steer performance when supplementing medium quality hay with a blend of soybean hulls and corn gluten feed (SH/CGF). The 86d feeding experiment was replicated over 4 years. Each year, 40 steers (BW=263±2.5, 281±2.5, 271±2.9, 229±2.9kg for years 1–4, respectively) were stratified by body weight and assigned to 8 groups which were randomly assigned to treatment. During years 1 and 2, treatments consisted of ad libitum medium quality fescue hay (70–100g/kg CP and 340–410g/kg acid detergent fiber) that was either not supplemented (HAY), supplemented daily (7X) with 2.73kg/hd, or supplemented on Monday, Wednesday and Friday (3X) with 6.36kg/hd. During years 3 and 4, an additional treatment was added in which steers were supplemented on Monday and Thursday with 9.55kg/hd of SH/CGF (2X). Average daily gain was higher (P<0.01) in supplemented steers compared to non-supplemented steers, but did not differ due to supplementation frequency. Hay intake was reduced (P<0.01) by supplementation and was higher (P<0.05) for 7X compared to both 3X and 2X, but hay intake did not differ between 3X and 2X. The gain to feed ratio was increased by supplementation (P<0.01) and was further increased by less frequent supplementation (P≤0.02). Results suggest that when supplementing medium quality hay with a blend of soyhulls and corn gluten feed, steers can be supplemented as little as twice a week without reducing performance. [Copyright &y& Elsevier]

Four ruminally and duodenally cannulated Suffolk weather lambs (34.5 ± 2.0 kg initial BW) were used in a 4 x 4 Latin square-designed experiment to examine the effects of ruminal protein degradability and supplementation frequency on site and extent of digestion in lambs consuming a low-quality forage diet. Wethers were fed a basal diet of mature crested wheatgrass hay (4.2% CP) for ad libitum consumption plus 1 of 4 supplements: 1) a high RDP supplement provided daily (RDP-D), 2) the high RDP supplement provided on alternate days (RDP-A), 3) a high RUP supplement provided on alternate days (RUP-A), or 4) a 50:50 mixture of the RDP and RUP supplements, provided on alternate days (MIX-A). Forage OM, N, NDF, or ADF intakes were not affected by treatment. True ruminal OM digestibility was greater (P < 0.001) for MIX-A lambs compared with other treatments. True ruminal N digestibility was less (P < 0.01) in RUP-A lambs compared with other treatments. Ruminal digestibilities of NDF and ADF were greater (P < 0.01) for MIX-A lambs compared with other treatments. There was a treatment x hour interaction (P < 0.001) with a delay in peak concentrations within the RDP-A lambs. However, lambs supplemented with RUP had less (P < 0.001) ruminal ammonia concentrations compared with RDP-D lambs, with RUP-A lambs exhibiting the least concentrations and least variation over time. Ruminal urease activity was not affected by treatment. Microbial N flow was not affected by treatment; however, there was an increase (P = 0.004) in microbial efficiency for RDP-D lambs. Alternate day protein supplementation with a mixture of RDP and RUP may improve digestibility in lambs consuming low-quality forage, which may be related to decreased fluctuation in ruminal ammonia concentrations as a result of greater endogenous N recycling. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to compare performance and metabolic responses of beef females consuming low-quality forages and offered an energy supplement based on fibrous byproducts daily (S7) or 3 times per week (S3) at similar weekly rates. In Exp. 1, BW gain, reproductive performance, mRNA expression of hepatic and skeletal muscle genes associated with nutritional metabolism and growth, and concentrations of blood urea nitrogen (BUN), plasma glucose, insulin, and IGF-I were assessed in 56 Brahman x Angus heifers supplemented at a daily rate of 1.0% of BW. Mean BW gain was greater (P = 0.03) for S7 compared with S3 heifers. Treatment x sampling day interactions were detected (P < 0.01) for all blood measurements. Heifers provided S7 had less daily variation in concentrations of BUN, glucose, and insulin, and frequently had greater (P < 0.05) concentrations of IGF-I compared with S3 heifers. Expression of liver IGF-I mRNA was greater (P = 0.04) for S7 heifers compared with S3 heifers. Treatment x day interactions were detected (P ⩽ 0.05) for mRNA expression of liver IGFBP-3, gluconeogenic enzymes, and muscle myostatin because the expression of these transcripts was greater (P < 0.05) for S3 heifers when both treatment groups were supplemented, but was similar or greater (cytosolic phosphoenolpyruvate carboxykinase; P = 0.04) for S7 heifers when only these were supplemented. Attainment of puberty and pregnancy were hastened (P = 0.03 and 0.02, respectively) in S7 heifers compared with S3 heifers. In Exp. 2, 12 Brahman x British mature cows received S3 or S7 for a 3-wk period at a daily rate of 0.5% of BW. Concentrations of BUN were greater for S7 compared with S3 cows (P < 0.03). A treatment x time interaction was detected (P = 0.01) for insulin concentrations because a time effect was significant (P < 0.01) for S3 but not S7 cows. With the advance of the experiment, concentrations of IGF-I increased for S7 (P < 0.01) but not S3 cows (treatment x week interaction; P = 0.02). The combined expression of gluconeogenic enzymes mRNA tended to be greater (P = 0.09) for S3 cows when both treatment groups received supplements, but was greater (P = 0.03) for S7 cows when only these were supplemented (treatment x day interaction; P < 0.01). In conclusion, offering an energy supplement based on fibrous byproducts daily instead of 3 times weekly enhanced the nutritional and metabolic status of forage-fed Brahman-crossbred females, resulting in improved growth and reproductive performance of developing heifers. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the fermentation activity of ruminal inoculum from cattle fed fresh pasture and supplemented or not with corn grain at different daily frequencies. Twenty heifers with ruminal catheters were randomly assigned to four treatments. Animals were fed pasture ad libitum and non-supplemented (T0) or supplemented with corn grain at 1% of bodyweight offered in one (T1), two (T2) or eight (T8) meals per day. After 20 days of adaptation, ruminal inoculum of each heifer was used to evaluate fermentation activity by the in vitro gas-production technique, using alfalfa, white clover or ryegrass as substrates. Gas production was measured at 2, 4, 6, 8, 10, 12, 18, 24, 48, 72 and 96 h from the beginning of incubation. Data were fitted to an exponential model and potential gas volume, fractional rate of gas production and lag time were analysed by PROC MIXED, considering the effect of treatment and substrate, and their interaction. The three parameters were affected by the substrate. Supplementation frequency did not affect the potential gas volume or the fractional rate of gas production. An interaction between treatment and substrate was detected (P < 0.01) on lag time, but only when ryegrass was used as the substrate. In conclusion, increasing the frequency of supplementation did not show benefits for the fermentation activity of ruminal inoculum, at least when the type of pasture used in this experiment was supplemented with corn at 1% of bodyweight. This study evaluated rumen fermentation activity of heifers fed pasture supplemented with corn at different daily frequencies. Increasing supplementation frequency did not show benefits, at least with this type of pasture (9% of crude protein, 60% of neutral detergent fiber) at this supplementation rate (1% BW) with corn. [ABSTRACT FROM AUTHOR]