Little is known about the gender differences in energetic requirements of goats in early life. In this study, we determined the energy requirements for maintenance and gain in intact male, castrated male and female Saanen goat kids using the comparative slaughter technique and provide new data on their body composition and energy efficiency. To determine the energy requirements for maintenance, we studied 21 intact males, 15 castrated males and 18 females (5.0±0.1 kg initial body weight (BW) and 23±5 d of age) using a split-plot design with the following main factors: three genders (intact males, castrated males, and females) and three dry matter intake levels (ad libitum, 75% and 50% of ad libitum intake). A slaughter group included three kids, one for each nutritional plane, of each gender, and all three animals within a group were slaughtered when the ad libitum kid reached 15 kg in BW. Net energy requirements for gain were obtained for 17 intact males, eight castrated males and 15 females (5.1±0.4 kg BW and 23±13 d of age). Animals were fed ad libitum and slaughtered when they reached 5, 10, and 15 kg in BW. A digestion trial was performed with nine kids of each gender to determine digestible energy, metabolizable energy and energy metabolizability of the diet. Our results show no effect of gender on the energy requirements for maintenance and gain, and overall net energy for maintenance was 205.6 kJ/kg0.75 empty body weight gain (EBW) (170.3 kJ/kg0.75 BW) from 5 to 15 kg BW. Metabolizable energy for maintenance was calculated by iteration, assuming heat production equal to metabolizable energy intake at maintenance, and the result was 294.34 kJ/kg0.75 EBW and km of 0.70. As BW increased from 5 to 15 kg for all genders, the net energy required for gain increased from 9.5 to 12.0 kJ/g EBW gain (EWG), and assuming kg = 0.47, metabolizable energy for gain ranged from 20.2 to 25.5 kJ/g EWG. Our results indicate that it is not necessary to formulate diets with different energetic content for intact male, castrated male and female Saanen goat kids weighing from 5 to 15 kg.

RESUMO -Utilizaram-se nove novilhos Nelore fistulados no rúmen mantidos em nove piquetes de capim-marandu (Brachiaria brizantha cv. Marandu) sob suplementação diária (sete vezes por semana); de segunda a sexta-feira (cinco vezes por semana); ou às segundas, quartas e sextas-feiras (três vezes por semana). Amostras de líquido ruminal foram coletadas em dois dias: um dia em que todos os animais receberam suplemento (dia 1) e outro subsequente, no qual somente os animais sob suplementação diária receberam suplemento (dia 2). A frequência de suplementação não alterou a ingestão de matéria seca de forragem, a ingestão de matéria seca total e a digestibilidade total da matéria seca. As variáveis foram afetadas somente pelo período, com redução significativa do mês de março para o mês de maio. A frequência de suplementação não afetou o pH ruminal. Para N-NH 3 ruminal, observou-se interação frequência de suplementação × dia de coleta × horário de coleta. No dia 1 a concentração de N-NH 3 não diferiu entre os horários após a suplementação entre os animais sob suplementação diária, enquanto no dia 2 houve um pico de produção de N-NH 3 3 horas após a suplementação. Entre os animais sob suplementação cinco vezes por semana, a diferença entre os dias 1 e 2 foi ocasionada pelo tempo 12 do dia 2 (7 mg/dL). Na suplementação três vezes por semana, no dia 1 o pico de N-NH 3 ocorreu 3 a 9 horas após a suplementação. A frequência de suplementação afetou somente a concentração de AGCC totais no dia 1 e a concentração de ácido butírico no dia 2. O mês do ano não afeta o pH e a concentração de N-NH 3 , mas os AGCC diminuem significativamente do mês de março para o mês de maio.Palavras-chave: ácidos graxos de cadeia curta, amônia ruminal, capim tropical, estratégia de suplementação, pH ruminal, transição águas/secas Influence of supplementation frequency on intake, digestibility and ruminal fermentation in beef cattle steers grazing palisade grass ABSTRACT -Nine ruminally fistulated Nellore steers were located in nine paddocks of palisade grass (Brachiaria brizantha cv. Marandu) pasture under daily supplementation (seven times per week), from Monday to Friday (five times per week) or Monday, Wednesday and Friday (three times per week). Ruminal fluid was sampled on two consecutive days. On the first day, all the animals that were supplemented (D1) and other subsequent day in which only for the animals under daily supplementation received the supplement (D2). The supplementation frequency did not affect the forage DMI, total DMI and DMD. The DMI and DMD were influenced by the experimental period, with reduction from March to May. Ruminal pH was not affected by the supplementation frequency. Supplementation frequency × collection day × collection hour interaction was observed for ruminal NH 3 -N. No difference in the D1 was observed in NH 3 -N concentration among the hours after supplementation in the daily supplementation frequency, while in the D2 there was a peak of NH 3 -N production 3 hours after supplementation. Among the animals un...

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The objective of the present experiment was to evaluate the ability of n-alkanes to estimate dry matter (DM) intake (DMI) and digestibility (DMD) in Nellore beef cattle fed a tropical grass cut at two growth stages (30 or 60 days). The effect of two different faecal sampling procedures (daily pool-Total-or rectal spot-Spot-samples) was also tested. Differences in faecal concentration between sampling methods were lower than 2% and 0.7% for 30-d and 60-d old grass, respectively, with slightly higher values in Spot samples. Faecal recoveries were not affected by the grass growth stage, except in the cases of C 31 , C 33 , and C 35 (P b 0.05), which were lower for 30-d compared to 60-d. There was lower ratio (P b 0.05) between internal and external recovery alkane pairs C 31 /C 32 , C 33 /C 32 and C 35 /C 36 in treating 30-d treatment than in 60-d old grass. Faecal recovery of natural alkanes increased with chain length, recoveries up to 77.0% (C 35 ), whereas dosed alkanes C 28 , C 32 and C 36 showed average recoveries of 94.2%, 97.2% and 86.8%, respectively. Estimates of DMI were different from current values (P b 0.05) when used C 31 /C 32 , C 33 /C 32 and C 35 /C 36 natural/dosed alkane pairs, regardless of the sampling procedure. An exception was the DMI estimated using the C 35 /C 36 alkane pair of the samples of total sampling, which does not differ from the actual values (P N 0.05). However, using recovery-corrected faecal concentrations reduced the differences between observed and estimated values (P N 0.05). Similarly, the DMD was underestimated with the alkanes C 31 , C 33 and C 35 , regardless of the method of sampling. Observed effect of forage development stage in the estimates of DMD (P b 0.05), (lower values for 30-d treatment were observed than in the 60-d), due to lower faecal recovery of alkanes in the 30-d treatment. By correcting the concentrations of alkanes with the faecal recovery of the individual alkane, the differences between the estimated and actual values were canceled (P N 0.05), regardless of age of forage, the alkane used or the sampling method.

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The current mineral requirements for growing goat kids are based on sheep and cattle studies without differentiating between the stages of development or gender. The aims of this study were to determine the net requirements for growth of Ca, P, Mg, Na and K of Saanen goat kids during the initial stages of growth and to analyse the effect of gender on the net requirements for growth of these macrominerals. Eighteen female, 19 intact male and 10 castrated male Saanen goat kids were studied. The kids were selected applying a completely randomized design and slaughtered when their body weight (BW) reached approximately 5, 10 and 15 kg to determine the mineral requirements for growth at these stages. The net mineral requirements for growth were similar among genders. The goat kids had slightly increased net requirements of Ca, P and Mg for growth with increasing BW from 5 to 15 kg. The net requirements for growth of Ca, P, Mg, Na and K ranged from 9.61 to 9.67 g/kg of BW gain, 7.14 to 7.56 g/kg of BW gain, 0.34 to 0.37 g/kg of BW gain, 1.26 to 1.13 g/kg of BW gain, 1.88 to 1.82 g/kg of BW gain as the animals grew from 5 to 15 kg respectively. In conclusion, when formulating diets for Saanen goat kids in early growth stage mineral levels do not need to adjusted based on gender.

Objetivou-se de avaliar a substituição parcial (574 g.kg-1) do farelo de soja por feno ou silagem de Gliricidia sepium sobre o desempenho, comportamento ingestivo e características de carcaça de cordeiros em terminação. Foram utilizados 18 cordeiros ½ Dorper × ½ Santa Inês, inteiros, com aproximadamente 120 dias de idade, peso vivo médio inicial de 21 ± 2.2 kg, confinados, em um delineamento experimental inteiramente casualizado, com três tratamentos e seis repetições. Os ingredientes utilizados nas dietas experimentais foram feno de capim elefante (Pennisetum purpureum), farelo de soja, milho moído, feno e silagem de Gliricídia. Sendo que, os tratamentos foram constituídos da dieta controle, com 100% de farelo de soja; feno de Gliricídia contendo 426 g.kg-1 de farelo de soja e 574 g.kg-1 de feno de Gliricídia; e silagem de Gliricídia contendo 426 g.kg-1 de farelo de soja e 574 g.kg-1 silagem de Gliricídia.  Os animais alimentados com feno de Gliricídia em substituição parcial ao farelo de soja, obtiveram maiores (P<0,05) consumos de matéria seca, proteína bruta, fibra em detergente neutro e nutrientes digestíveis totais. Observou-se maior consumo de água para o tratamento de feno de Gliricídia. Observou-se maior (P<0,05) ganho médio diário, peso vivo ao abate, peso de carcaça quente e peso de carcaça fria para os tratamentos contendo feno e silagem de Gliricídia. A substituição parcial do farelo de soja por feno ou silagem de Gliricídia e indicada para ser utilizada na dieta de cordeiros em terminação, por proporcionar maior desempenho e peso de carcaça nos animais. Contudo, a silagem de Gliricídia demonstra maior potencial para ser utilizada na dieta de cordeiros em terminação, sobretudo em regiões semiáridas por reduzir o consumo de água dos animais.

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