The objective of the present study was to evaluate the effect of increasing levels of prepartum and postpartum protein supplementation on nutrient intake and digestibility, productive performance and metabolic status of beef heifers on tropical pasture. Twenty-eight pregnant beef heifers with bodyweight and body condition score of 459.7 ± 6.8 kg and 5.8 ± 0.10 respectively, were used. The experiment was performed according to a completely randomised design, with the following four treatments: 0.0, 0.4, 0.8 and 1.2 kg/animal.day of protein supplement containing 25% crude protein. All animals received a mineral mixture ad libitum. The experiment lasted 210 days, divided into three experimental periods. The supplementation level increased the intake of all evaluated nutrients, digestibility of organic matter, neutral detergent fibre corrected for ash and protein, as well as higher average daily gain prepartum and bodyweight of calves at birth (P < 0.05). Protein supplement at the levels evaluated did not affect body condition score (P > 0.05). An interaction effect between treatment × days in relation to calving occurred for concentrations of serum urea nitrogen, total proteins, albumin and globulins (P < 0.05). Supplementation did not affect glucose, triglyceride, non-esterified fatty acids, β-hydroxybutyrate or progesterone (P > 0.05). In conclusion, supply of up to 1.2 kg/day of protein supplement for grazing beef heifers optimises forage intake and average daily gain before calving, and improves the indicators of the protein status.

BackgroundNutrition is one of the most important factors that affect animal performance, and it therefore also impacts on financial results in beef systems. In this way, finding the best strategy for feeding supplements is of paramount importance. Aiming to evaluate the effect of supplement feeding strategies for beef cows in the last third of gestation, two experiments were conducted. In Experiment 1, 35 pregnant Nellore cows were assigned to a completely randomized design with four treatments: control, which received no supplement; supplementation for the last 30 d of gestation (30-d; 3.0 kg/d); supplementation for the last 60 d of gestation (60-d; 1.5 kg/d); or supplementation for the last 90 d of gestation (90-d; 1.0 kg/d). All supplemented treatments received the same total amount of supplement throughout the experiment: 90 kg (20% of crude protein). A second experiment (Experiment 2) was delineated to evaluate the effects of the amounts offered in Experiment 1 on intake and metabolism. Four multiparous pregnant Nellore cows were assigned to a 4 × 4 Latin square design, with periods of 15 d each.ResultsThere was a linear effect of the number of days of supplementation on calving body weight (BW; P < 0.05) and a quadratic effect on BW change from parturition to d 31 post-calving (P < 0.05), with cows on the 60-d strategy losing less BW post-calving. No difference was found in offspring birth BW (P > 0.10). A significant linear effect on interval from parturition to conception (P < 0.05) was observed, with the highest calving to conception interval being observed in the 90-d strategy. The level of supplementation did not affect forage intake or neutral detergent fiber digestibility (P > 0.10). Nitrogen excreted through urine tended to increase linearly with the level of supplementation (P < 0.10).ConclusionProviding 1.5 kg of supplement during the last 60 d of gestation improves cow performance after calving, reducing the magnitude of BW lost, and reduces the number of days from calving to re-conception in the following breeding season compared to the usually recommended period of supplementation of 90 d pre-partum.

The aim of this study was to evaluate the effects of supplementation with different crude protein contents on the productive performance of grazing beef cows during post-calving. Thirty-six beef cows, with age and average body weight of 5 years and 490±17.9 kg, respectively, were used. The experimental design was completely randomized. The treatments were: control = cows received only mineral mixture ad libitum; supplemented = cows received 1 kg d -1 of supplement containing 80, 200, or 320 g crude protein (CP) kg -1 . There was no effect (P ≥ 0.16) of supplementation on voluntary intake. A linear effect (P < 0.02) of the CP content in the supplements was observed among supplemented cows, only for the CP intake. Supplementation did not affect (P ≥ 0.20) the total digestibility of organic matter, neutral detergent fiber corrected for ash and protein, and CP. Among supplemented cows, a positive linear effect (P < 0.01) of the CP content in the supplement was observed for the CP digestibility. Intestinal flow of microbial nitrogen compounds and efficiency of synthesis microbial were not affected (P ≥ 0.18) by treatments. Performance, milk yield and composition were not also affected (P ≥ 0.11) by treatments. Supplementation did not affect (P ≥ 0.52) non-esterified fatty acids, urea nitrogen and progesterone serum concentrations. It is concluded that supplementation of grazing beef cows during post-calving does not affect nutritional and productive performance. Key words: Beef cows. Intake. Nellore. Non-esterified fatty acids. Supplementation. ResumoObjetivou-se avaliar os efeitos da suplementação com diferentes teores de proteína sobre o desempenho produtivo de vacas de corte em pastejo durante o pós-parto. Foram utilizadas 36 vacas de corte com idade e peso corporal médio de 5 anos e 490±17,9 kg, respectivamente. O delineamento experimental foi inteiramente casualizado. Os tratamentos foram: controle = vacas receberam somente mistura mineral ad libitum; suplementados = vacas receberam 1 kg dia -1 de suplemento contendo 80, 200 ou 320 g de proteína bruta (PB) kg -1 . Não houve efeito (P ≥ 0,16) da suplementação sobre consumo voluntario. Entre os animais suplementados, o consumo de proteína aumentou linearmente (P < 0,02) com o teor de PB no suplemento. A suplementação não afetou (P ≥ 0,20) a digestibilidade total da matéria orgânica, fibra em detergente neutro corrigida para cinza e proteína (FDNcp) e da proteína. Entre os animais suplementados, houve efeito linear positivo (P < 0,01) dos teores de PB nos suplementos sobre a digestibilidade da PB. O fluxo intestinal de compostos nitrogenados microbianos e a eficiência de síntese de proteína microbiana não foram afetados (P ≥ 0,18) pelos tratamentos. O desempenho, produção e a composição do leite não foram afetados (P ≥ 0,11) pelos tratamentos. A suplementação não afetou (P ≥ 0,52) as concentrações séricas de ácidos graxos esterificados, ureia e progesterona. Conclui-se que a suplementação de vacas de corte em pastejo durante pós-parto não afeta o consumo e ...

The aim of this study was to evaluate the effect of different energy sources -corn, sorghum, and wheat bran -on performance, intake, digestibility, and nitrogen utilization efficiency of beef calves subjected to creep feeding. Thirty-four calves (12 males and 22 females) with initial age and weight of four months and 108±3.9 kg, respectively, were used in a randomized-block experimental design with four treatments and two blocks (males and females). Treatments were control (MM), a mineral mixture ad libitum; corn (C); corn + sorghum (C+S); and corn + sorghum + wheat bran (C+S+WB). Supplements contained approximately 20% crude protein (CP), and were fed in the amount of 0.5% of body weight. Supplemented animals had higher performance (P<0.05) when compared with those on treatment MM. Supplementation increased (P<0.05) the intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber corrected for ash and protein (NDFap), non-fibrous carbohydrates (NFC), digestible neutral detergent fiber (dNDF), and digestible organic matter (dOM). The digestibility of NFC was higher (P<0.05) in the supplemented treatments. The C+S and C+S+WB treatments provided increased digestibility (P<0.05) of OM, CP, and NDFap. The synthesis of nitrogen compounds was higher (P<0.05) in animals on treatment C as compared with those on the other supplemented treatments. Animals on treatments C+S and C+S+WB had higher (P<0.05) nitrogen utilization efficiency compared with those on the other treatments. Concentrate supplementation improved the animal performance. The use of other energy sources (sorghum or wheat bran) in association with corn is recommended for suckling calves. ResumoO objetivo deste trabalho foi avaliar o efeito de diferentes fontes energéticas, milho, sorgo e farelo de trigo, sobre o desempenho, o consumo, a digestibilidade aparente total dos constituintes da dieta e a eficiência de utilização dos compostos nitrogenados em bezerros de corte submetidos ao creep feeding. Foram utilizados 34 bezerros lactentes (12 machos e 22 fêmeas) com idade e peso médio inicial de quatro meses e 108±3,9 kg, respectivamente. O experimento foi conduzido em blocos casualizados com quatro tratamentos e dois blocos (machos e fêmeas). Os tratamentos foram: controle (MM), fornecimento de mistura mineral ad libitum aos animais; milho (M); milho + sorgo (M+S) e milho + sorgo + farelo de trigo (M+S+FT). Os suplementos continham aproximadamente 20% de proteína bruta (PB) e foram fornecidos na quantidade de 5 g kg -1 do peso corporal. Os animais suplementados apresentaram maior (P<0,05) ganho de peso quando comparados com os animais do tratamento MM. A suplementação aumentou (P<0,05) os consumos de matéria seca (MS), matéria orgânica (MO), PB, fibra em detergente neutro corrigida para cinzas e proteína (FDNcp), carboidrato não fibroso (CNF), fibra em detergente neutro digerida (FDNd) e matéria orgânica digerida (MOD). A digestibilidade aparente total do CNF foi maior (P<0,05) nos animais suplementados. Os tratamento...

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