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In reproductive swards, stems can act as a barrier that affects the grazing behaviour of ruminant livestock. The barrier effect of stems is closely associated with both the force required to fracture the stems and the density of these stems (in combination, these make up grazing resistance), and these factors need to be considered when making predictions about the forage intake of ruminants grazing reproductive pastures. Differences in grazing resistance between sward canopy layers of different grass species are thought to affect bite dimensions, but data are scarce. In this study, we assessed the grazing resistance for three canopy layers of seven tropical grass species. Species differed significantly in grazing resistance for every canopy layer, with a general ranking order for grazing resistance, in ascending order: Cenchrus ciliaris (' American' buffel), Digitaria milanjiana (' Jarra' finger grass), Setaria surgens (annual pigeon grass), Setaria sphacelata (' Narok' setaria), Dichanthium sericeum ( Queensland bluegrass), Chloris gayana (' Callide' Rhodes grass). In the top canopy layer, grazing resistance did not appear to create a barrier for any of the species, but in the bottom canopy layer, it did for all species. Species also differed in the relative contribution of fracture force and density to grazing resistance. The results highlight the importance of managing the grazing systems to minimize the barrier effect of the stems, which can be done by controlling the phenological stage of the pasture and the grass species and animal size used in the system. [ABSTRACT FROM AUTHOR]

Improving the productivity and profitability of smallholder cattle enterprises in Indonesia requires greater and more efficient utilisation of underutilised feed resources such as rice straw. The experiment tested the hypothesis that an Ongole cow with low energy requirements can maintain weight (W) on a rice straw-based diet with the addition of a small amount of tree legumes. Thirty-two Ongole cross (Bos indicus) cows were allocated to one of four treatments in a randomised block design with eight cows per treatment. Cows were offered untreated rice straw ad libitum with four levels of tree legumes (0, 11, 21, and 42 g DM/kg W[sup 0.75].day) for 20 weeks. Feed intake was determined daily and liveweight was measured every second week. There was no difference in total feed intake between the treatment groups (P > 0.05). Intake of tree legumes was higher when more was offered (P < 0.05), but cows did not consume all of the legumes offered to them. The inclusion of tree legumes in the diet had no effect on organic matter digestibility, ME content of the diet, liveweight gain or estimated energy balance of the cows (P > 0.05). Rice straw alone contained insufficient ME and rumen-degradable N to meet the maintenance requirements of the cows. From the regression relating liveweight change and ME intake for all cows across all diets, the inclusion of tree legumes in the diet at ~12 g DM/kg W[sup 0.75].day or 2.8 g DM/kg W.day was enough to meet the energy requirements for maintenance of Ongole cows fed rice straw ad libitum. Improving the productivity of smallholder cattle enterprises in Indonesia requires greater and more efficient utilisation of feed resources. The aim of this experiment was to find the amount of tree legumes required to meet the maintenance requirements of an Ongole cow fed rice straw ad libitum, which was 12 g DM/kg W[sup 0.75].day. This diet could be used for cattle with low energy requirements while higher quality feeds are directed to pregnant, lactating and growing cattle. [ABSTRACT FROM AUTHOR]

Three experiments were conducted to determine liveweight (W) gain and feed and water intake of weaned Bali cattle offered a range of feed types. In each experiment, 18 weaned entire male Bali cattle were allocated to three treatment groups in a completely randomised block design, with six replicates (animals) per treatment. The dietary treatments were: Experiment 1, native grass fed ad libitum, native grass supplemented with rice bran at 10 g dry matter (DM)/kg W.day and native grass supplemented with a mixture of rice bran and copra meal in equal proportions fed at 10 g DM/kg W.day; Experiment 2, elephant grass hay fed ad libitum, elephant grass supplemented with gliricidia at 10 g DM/kg W.day, and gliricidia fed ad libitum; and Experiment 3, corn stover fed ad libitum, corn stover supplemented with gliricidia at 10 g DM/kg W.day, and corn stover supplemented with rice bran/copra meal in equal amounts (w/w) at 10 g DM/kg W.day. Each experiment was 10 weeks in duration, consisting of a 2-week preliminary period for adaptation to diets and an 8-week experimental period for the measurement of W change, feed and water intake and digestibility of the diet. Growth rates of 6-12-month-old, entire male Bali cattle fed a range of local diets ranged from 0.10 and 0.40 kg/day. Lowest growth rates occurred when the cattle were given the basal diets of native grass (0.104 kg/day), elephant grass (0.174 kg/day) and corn stover (0.232 kg/day). With the addition of supplements such as rice bran, rice bran/copra meal or gliricidia to these basal diets liveweight gains increased to between 0.225 and 0.402 kg/day. Forage DM intake was reduced with these supplements by on average 22.6% while total DM intake was increased by an average of 10.5%. The growth rate on gliricidia alone was 0.269 kg/day and feed DM intake was 28.0 g/kg W.day. Water intake was not affected by supplement type or intake. In conclusion, inclusion of small quantities of locally available, high quality feed supplements provide small-holder farmers with the potential to increase growth rates of Bali calves from 0.1 to 0.2 kg/day, under prevailing feeding scenarios, to over 0.4 kg/day. Bali cattle are the predominant cattle breed reared by small-holder farmers across eastern Indonesia. Experiments were conducted to evaluate various feeding strategies which increased the liveweight gain of weaned Bali cattle to over 0.4 kg/day compared to 0.1 kg/day under existing management systems. Implementation of these findings may improve income and livelihoods of small-holder farmer households in eastern Indonesia. [ABSTRACT FROM AUTHOR]

Cocoa-pods, a by-product of the cocoa industry, could potentially be used as a feed resource for ruminants in eastern Indonesia. However, little is known regarding the optimal amount to be included in the diet or the effect of treatment with Aspergillus niger on cocoa-pod quality. In this experiment the effect of rate of inclusion (0 or 10 gDM/kgliveweight.day or ad libitum) of A. niger-treated or untreated cocoa-pods in the diet on intake and liveweight gain of Bali cattle (Bos sondaicus) was investigated. Ad libitum intake of cocoa-pods was greater when they were treated with A. niger (17.1 ± 0.07 g DM/kg liveweight.day; mean ± s.e.m.) compared with untreated cocoa-pods (13.9 ± 0.19 g DM/kg liveweight.day) when offered as the sole component of the diet. The digestibility of A. niger-treated cocoa-pods (448.9 ± 23.7 g/kg) was not different to untreated cocoa-pods (422.9 ± 13.9 g/kg) when fed ad libitum, which was lower than native grass (527.2 ± 10.7 g/kg). Animals offered A. niger-treated cocoa-pods lost less liveweight than animals offered untreated cocoa-pods when offered ad libitum (-0.104 ± 0.02 and -0.280 ± 0.02 kg/day, respectively), and grew faster when included in the diet at 10 g DM/kg liveweight.day (0.233 ± 0.02 and 0.129 ± 0.02 kg/day, respectively). In conclusion, in areas where cocoa plantations exist, cocoa-pods may be a useful feed resource for ruminants when fed at low levels of inclusion in the diet. The treatment of cocoa-pods with A. niger will result in increased liveweight gain. However, it is unlikely such treatments will be adopted by small-holder farmers due to the increased requirements for inputs, such as time, labour, funds, equipment, and technical skills. [ABSTRACT FROM AUTHOR]

Rates of secretion of components into milk are a function of precursor concentrations and parameters that describe expression of the milk synthetic enzymes and their sensitivity to precursor concentrations. To establish the enzymatic sensitivities of milk fat yield and mammary acetate utilization to circulating acetate concentration, lactating cows were infused for 10 h with 0 or 40 g of acetate/h in an external iliac artery supplying one udder half. In addition, to investigate the possibility that energy supply influences the milk protein response to an elevated amino acid (AA) concentration, 2 different AA profiles were infused with and without acetate. Six cows, fed a total mixed ration of 21% crude protein ad libitum, were infused with AA at 0 g/h, 30 g/h in the profile of rumen microbes, or 30 g/h in the profile of milk proteins, in a 3 x 2 factorial arrangement with the 2 acetate treatments of 0 and 40 g/h, all in a 6 x 6 Latin square. Amino acid infusion caused a 60% increase, on average, in plasma concentration of AA entering the infused udder half. From the microbial AA profile, 49% of infused AA were taken up by the udder half, 42% of which occurred during the first pass. From the milk AA profile, 44% of infused AA were taken up by the udder half, 50% of which occurred during the first pass. There was an 8% increase in yield of milk protein with AA infusion, representing 7% capture, but no effect of the infused profile. Acetate infusion caused a decrease in the yields of milk protein and lactose when AA were infused, but not when AA were absent. Milk fat yields were not affected, although acetate concentrations in plasma entering the infused udder half increased by 123% and mammary uptakes increased by 128%. Mammary uptakes of long-chain fatty acids and β-hydroxybutyrate were not affected by acetate infusion, whereas glucose uptakes tended to increase. It was suggested that excess acetate may have been sequestered in adipose tissue in the udder. Yields of both protein and fat in milk showed a low sensitivity to the concentration of their precursors in circulation. It was concluded that the Km in Michaelis-Menten-type equations describing milk synthesis should be assigned a low value, and that the Vmax is regulated to bring about changes in milk yield and composition. [ABSTRACT FROM AUTHOR]

The effects of heat stress on dairy production can be separated into 2 distinct causes: those effects that are mediated by the reduced voluntary feed intake associated with heat stress, and the direct physiological and metabolic effects of heat stress. To distinguish between these, and identify their effect on milk protein and casein concentration, mid-lactation Holstein-Friesian cows (n = 24) were housed in temperature-controlled chambers and either subjected to heat stress [HS; temperature-humidity index (THI) ~78] or kept in a THI < 70 environment and pair-fed with heat-stressed cows (TN-R) for 7 d. A control group of cows was kept in a THI < 70 environment with ad libitum feeding (TN-AL). A subsequent recovery period (7 d), with THI < 70 and ad libitum feeding followed. Intake accounted for only part of the effects of heat stress. Heat stress reduced the milk protein concentration, casein number, and casein concentration and increased the urea concentration in milk beyond the effects of restriction of intake. Under HS, the proportion in total casein of αS1-casein increased and the proportion of αS2-casein decreased. Because no effect of HS on milk fat or lactose concentration was found, these effects appeared to be the result of specific downregulation of mammary protein synthesis, and not a general reduction in mammary activity. No residual effects were found of HS or TN-R on milk production or composition after THI < 70 and ad libitum intake were restored. Heat-stressed cows had elevated blood concentrations of urea and Ca, compared with TN-R and TN-AL. Cows in TN-R had higher serum nonesterified fatty acid concentrations than cows in HS. It was proposed that HS and TN-R cows may mobilize different tissues as endogenous sources of energy. [ABSTRACT FROM AUTHOR]

A reduction in voluntary feed intake is observed in ruminants consuming nutrient-deficient diets, such as those with a low CP or P content, and has been attributed to active metabolic regulation, rather than a physical constraint. The hypothalamus is the key integrator of feed intake regulation in mammals. The objectives of this experiment were to (1) establish a model of metabolic feed intake regulation in ruminants consuming diets of variable CP and P content, and (2) determine key biochemical pathways and influential points of regulation within the hypothalamus. Merino wethers [n = 40; 23.7 ± 1.4 kg liveweight (mean ± SD)] were fed one of five dietary treatments (n = 8/treatment) for 63 days in individual pens. The treatments included targeted combinations of high (H) and low (L) CP (110 and 55 g/kg DM) and high and low P (2.5 and 0.7 g/kg DM) with 9 MJ metabolisable energy (ME) per kg DM which were fed ad libitum (UMEI; unrestricted ME intake) resulting in four experimental diets (HCP-HP-UMEI, LCP-HP-UMEI, HCP-LP-UMEI and LCP-LP-UMEI). An additional nutritional treatment (HCP-HP-RMEI) restricted intake of the HCP-HP diet to an equivalent ME intake of wethers consuming the LCP-LP-UMEI treatment. Wethers offered the LCP-HP-UMEI, HCP-LP-UMEI and LCP-LP-UMEI treatments consumed 42, 32 and 49% less total DM (P ≤ 0.05), respectively than the HCP-HP-UMEI treatment, and this was not attributable to any physical limitation of the rumen. Plasma concentrations of urea nitrogen and inorganic phosphate indicated that these nutrient deficiencies were successfully established. To assess potential mechanisms, RNA-seq was conducted on samples from the arcuate nucleus (ARC), ventromedial hypothalamus and lateral hypothalamus of the wethers, yielding a total of 301, 8 and 148 differentially expressed genes across all pairwise comparisons, respectively. The expression of NPY, AGRP and CARTPT, known for their regulatory role in mammalian feed intake regulation, had a similar transcriptional response in the ARC of wethers consuming nutrient-deficient treatments and those consuming a ME-restricted treatment, despite these wethers expressing behaviours indicative of satiated and hungry states, respectively. In addition, genes involved with glycolysis (TPI1), the citric acid cycle (CS, OGDH, GLUD1, GOT1) and oxidative phosphorylation (COX5A, ATP5MC1, ATP5F1B, ATP5MC3) were downregulated in the ARC of wethers fed a nutrient deficient (LCP-LP-UMEI) relative to the non-deficient (HCP-HP-UMEI) treatment. In summary, a model for voluntary feed intake restriction was established to determine genome-wide molecular changes in the hypothalamus of young ruminants., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

There is a growing demand for beef products across developing countries. Formulating rations to include locally available waste products has the potential to increase the live weight gain (LWG) of cattle and improve the livelihoods of smallholder farmers; however, upper limit inclusion levels of cassava peel products require investigation. An experiment evaluated the effect of using cassava peel silage (CPS) at the DM inclusion levels of 30, 40, 50, 60 and 70% (with the remainder protein meals and maize stover in the diet) on the LWG of crossbred Limousin × Ongole bulls (269 ± 48.8 kg). Thirty bulls, approximately two years of age, were allocated in a completely randomised block design with six blocks based on initial live weight (LW) and five treatments based on level of CPS. The combination of CPS (with 2% urea of the CPS) and protein meals significantly affected LWG with the highest values obtained at levels of 30 and 50% inclusion of CPS (1.16-1.35 kg/day) (P < 0.05). Polynomial analysis of LWG data revealed the optimal LWG is theoretically achieved at 37% CPS with a LWG of 1.31 kg/day; however, LWG was similar from 30 to 50% inclusion levels and then declined. There was little significant difference at CPS inclusion levels of 30-60%, for DM intake (DMI) which ranged from 2.3 to 2.6% LW, organic matter (OM) digestibility (77.8-81.6%), feed conversion ratio (FCR) (6.56-7.56 kg DM/kg LWG) and feed cost of gain (Indonesia rupiah (IDR)/kg LW 18 612 - 21 398). At a high (70%) level of CPS inclusion, these values were markedly changed when compared to the 30% inclusion level of CPS. Feed treatments did not affect rumen pH, NH 3 -N, concentration or molar percentage of volatile fatty acids or protozoal population (P < 0.05). Rumen pH measured three hours after morning feed ranged from 6.7 to 6.8 and NH 3 -N ranged from 14.1 to 19.3 mg NH 3 -N/dl. It was concluded that inclusion of CPS up to 60% mixed with protein meals and urea and 20% maize stover maximised LWG and profitability of the production system., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Formulating rations with high energy and protein feeds such as cassava and locally sourced protein meals is an important strategy to increase live weight gain (LWG) of crossbred bulls in Indonesia. Current systems of production for Indonesian smallholders fatten bulls using cut and carry. Formulating a diet for an optimal combination of available feeds will increase production and potential profitability for smallholders. An experiment was conducted to evaluate the effect of using cassava meal in the diet at levels of 70C, 60C, 50C, 40C and 30C% (with most of the remainder being the protein meals) on the LWG of Limousin × Ongole bulls so as to determine the optimum combination of cassava meal and protein meals for LWG. Thirty bulls were allocated in a completely randomized block design with 6 blocks based on initial live weight (LW) and 5 treatments based on level of cassava meal. The combination of cassava meal (with 2% urea) and protein meals significantly affected LWG with the highest (1.35 kg/day) recorded at 40C (40% cassava meal, 40% protein meals and 20% maize stover). The LWG and nutrient intake increased curvilinearly with decreasing cassava meal and increasing protein meals (P < 0.05). Measured cassava meal inclusion in the final ration as a consequence of the changes in intake was 60, 56, 47, 37 and 28% for the designated 70C, 60C, 50C, 40C and 30C treatments, respectively. Dry matter intake reached 96 g/kg 0.75 per day or equal to 2.24% LW at this 40% level of inclusion. At the 70C treatment with 60% cassava meal and 9% protein meals, DM digestibility (69.1%) was lowest and that value increased as the proportion of cassava meal decreased and was highest at the 40C treatment (75.8%). Feed treatments significantly affected rumen pH, ammonia N (NH 3 N) and volatile fatty acid concentrations (P < 0.05). There was no significant effect on protozoal population (P > 0.05). Rumen pH ranged from 6.3 to 6.9. It was concluded that a combination of 40% dried cassava meal and 40% protein meals with roughage (20%) maximized intake and LWG and beyond that level of cassava meal inclusion, LWG and intake decreased markedly., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

A series of metabolism experiments investigated the recovery of continuous-, intravenously infused chromium complexed with ethylenediamine tetra-acetic acid (CrEDTA) and lithium sulphate in the urine of cattle with a view to using the markers to estimate urine and metabolite output in grazing cattle. The recovery of Cr in urine from these infusions was similar (90%) in metabolism trials when cattle consumed three very contrasting diets: high-grain formulated pellet, lucerne hay (Medicago sativa) or low-quality native grass hay (predominantly Heteropogon contortus). By contrast, Li recovery in urine averaged 46.3 ± 0.40% and 72.6 ± 0.43% for native pasture and lucerne hays, respectively, but was not constant across days. There was negligible transfer of Cr from CrEDTA in blood serum to the rumen or faeces, whereas appreciable quantities of infused Li were found in both. The ratio of urine volume estimated by spot samples and marker dilution of Cr, to urine volume measured gravimetrically, was 1.05. In grazing studies using rumen-fistulated (RF) steers grazing seven different tropical and temperate grass and legume pastures, the ratio of concentrations of purine derivatives (PD) to Cr in spot samples of urine was shown to vary diurnally in the range of 49% to 157% of the average 24 h value. This finding indicated the need for regular sampling of urine to achieve an accurate average value for the PD : Cr ratio in urine for use in estimating urinary PD excretion and hence microbial protein production in the rumen. It was concluded that continuous, intravenous infusion of CrEDTA resulted in a constant recovery of Cr in the urine of cattle across diets and, provided an intensive sampling regime was followed to account for diurnal variation, it would be suitable as a marker to estimate urine volume and urinary output of PD in grazing cattle.

The role of cholecystokinin (CCK) in modulating feed intake depression in parasite-infected lambs was investigated using CCK receptor antagonists (L364-718 and loxiglumide). Four experiments were carried out using ewe lambs infected with 4000 Trichostrongylus colubriformis larvae/d or non-infected controls (n8, live weight 25 kg). Animals were fed daily on a nutritionally complete pelleted diet and had free access to water. In the first experiment, infected and non-infected animals were injected subcutaneously with CCK antagonist (100 micrograms L364-718) or carrier alone as a single dose. In the second experiment, CCK antagonist (loxiglumide: 0, 5, 10 or 20 mg/kg live weight) was injected into a jugular vein immediately before feeding. In the third experiment, animals were infused continuously with the CCK antagonist (loxiglumide; 10 mg/kg per h) for 10 min before feeding and for the first 2 h of feeding. In the final experiment, lambs were fitted with an indwelling cerebral ventricular cannula and infused with a CCK antagonist (loxiglumide, 162 micrograms/min), CCK agonist (CCK-8, 2.5 pmol/min), loxiglumide plus CCK-8 or sterile saline solution alone via the cannula for 30 min before feeding and for the first 60 min of feeding. In all the experiments short-term feed intake was recorded at 10 and 15 min intervals for the first and second hours of feeding respectively, then at hourly intervals for the remainder of the 8 h recording period. Peripheral injection with L364-718 or loxiglumide did not elevate feed intake in either the infected or non-infected animals. However, feed intake was increased (P < 0.05) in the short term by central infusion of loxiglumide, this effect being greater in the infected animals and apparently due to an elevation in intake during the second hour of feeding. CCK-8 depressed short term feed intake only in the infected animals (P < 0.05). Total daily feed consumption was not influenced by any of the pharmacological agents. The results indicate an involvement of central CCK receptors in regulation of feed intake depression following gastrointestinal parasitism of sheep and the possibility of a similar role in non-infected sheep. They do not support the singular importance of a peripheral action of CCK in determining satiety.