Abstract We aimed to evaluate the effects of paternal genotypes (Piau, Duroc-based, and Pietrain) and nutritional plans with different digestible lysine contents (Low, Medium, and High) on performance, carcass, and meat quality traits of pigs. Pietrain and Duroc crossbred barrows and gilts were similar in performance and carcass traits and had the greatest values when compared to Piau crossbred pigs. Regarding meat quality, drip loss was greater in pork from Pietrain crossbred barrows and gilts compared to Duroc and Piau crossbred pigs. The High nutritional plan had the greatest daily digestible lysine intake value, followed by the Medium and Low nutritional plans. Most of the performance, carcass, and meat quality traits that were evaluated in barrows and gilts were not affected by the nutritional plans. In general, Duroc and Pietrain crossbred pigs had a greater performance and carcass yield when compared to Piau crossbred pigs.

ABSTRACT We evaluated blood parameters of Angus and Nellore bulls fed diets with and without forage. Forty animals with initial body weight (BW) of 380±16.2 kg were housed in individual stalls. Eight bulls of each breed were fed a whole shelled corn (WSC) diet [850 g kg−1 of WCS and 150 g kg−1 of a pellet based on soybean meal, dry mater (DM) basis] or a ground corn with silage (GC) diet (300 g kg−1 of silage and 700 g kg−1 of a concentrate based on corn and soybean meal, DM basis), ad libitum, and four animals of each breed were limited-fed the GC diet [feed restriction (FR), 55% of the DM intake of bulls fed ad libitum, adjusted for the metabolic BW]. Intake was measured daily, and a metabolism trial was conducted with total collection of feces and urine to estimate the ruminally degraded and undegraded protein (intake and nitrogen balance). Blood samples for determination of hormones and metabolites were collected. The data were analyzed using the GLM procedure of SAS adopting a significance level of 0.05. The diet affected only the serum concentrations of triglycerides, HDL, and VLDL, with limited-fed animals presenting smaller concentrations than ad libitum-fed bulls. No difference in blood parameters was observed between animals fed WSC or GC diets. Nellore bulls presented greater T4, cholesterol, HDL, LDL, and serum urea nitrogen concentrations than Angus. Feeding finishing beef cattle with no-roughage diets does not alter their blood parameters. Also, our results support that Zebu cattle might have lower serum removal of nutrients due to a lesser demand for fat and protein deposition than Bos taurus taurus.

Resumo: O objetivo deste trabalho foi quantificar as exigências nutricionais para a manutenção (NRm) e o crescimento (NRg), assim como o coeficiente de retenção (RC) de cálcio, fósforo, sódio, potássio e magnésio, de bezerros da raça Holandesa. As NRm foram de 87,8, 20,8, 4,36, 2,21 e 1,01 mg kg-1 da massa de corpo vazio para Ca, P, Na, K e Mg, respectivamente. O RC foi de 0,882, 0,473, 0,274, 0,088 e 0,052 para Ca, P, Na, K e Mg, respectivamente. As exigências nutricionais de Ca e P de bezerros da raça Holandesa são maiores do que aquelas estimadas para animais adultos.

Abstract: The objective of this work was to quantify the net requirements for the maintenance (NRm) and growth (NRg), as well as the retention coefficient (RC) of calcium, phosphorus, sodium, potassium and magnesium, of Holstein calves. The NRm were 87.8, 20.8, 4.36, 2.21, and 1.01 mg kg-1 of empty body weight for Ca, P, Na, K, and Mg, respectively. The RC was 0.882, 0.473, 0.274, 0.088, and 0.052 for Ca, P, Na, K, and Mg respectively. The requirements of Ca and P of Holstein calves are higher than those estimated for adult animals.

Abstract: Breeds of hair sheep play an important role in animal production in tropical regions; however, their nutrient requirements have not been determined to the same extent as those of wool breeds. Due to the environmental conditions of the tropical regions (climate, quality and availability of feedstuffs), it is reasonable to hypothesize that energy requirements and efficiency of utilization of metabolizable energy (ME) may be different between hair and wool breeds of sheep. Information available on hair sheep shows a large discrepancy regarding energy requirements. Based on available literature data for female sheep, ME requirement for maintenance (MEm) was 419±129 kJ/ kg BW0.75 (mean ± standard deviation) and for the male 388±123 kJ/kg BW0.75. The requirement of net energy for gain (NE g ) ranged from 8.75 to 14.06 kJ/g (11.63±1.86 kJ/g). The efficiency of ME utilization for maintenance (km ) and gain (kg ) were 0.66±0.02 and 0.42±0.04, respectively. This review indicated also that information is scarce for adult ewes at different physiological stages (maintenance, lactation, or pregnancy). More work is required regarding estimates of nutrient requirements of hair sheep in order to develop adjustments to existing nutrition models to predict animal’s response under the conditions prevailing in the tropics (animal type, environment and feedstuffs available).

Resumen: Los ovinos de pelo juegan un papel importante en la producción animal en las regiones tropicales; sin embargo, sus requerimientos nutricionales no se han determinado en la misma medida que los de las razas de lana. Debido a las condiciones ambientales de las regiones tropicales (clima, calidad y disponibilidad de alimentos), es razonable la hipótesis de que los requerimientos de energía metabolizable (EM) y la eficiencia de utilización de la EM pueden ser diferentes entre los ovinos de razas de pelo y de lana. La información disponible en ovinos de pelo muestra una gran discrepancia en cuanto a las necesidades de energía. Con base en datos de la literatura disponible para hembras ovinas, el requerimiento de EM para mantenimiento (EMm) fue de 419±129 kJ/kg PC0.75 (media ± desviación estándar) y para machos fue 388±123 kJ/kg BW0.75. El requerimiento de energía neta para la ganancia de peso (EN g ) varió de 8.75 a 14.06 kJ/g (11.63±1.86 kJ/g). Las eficiencias de utilización de la EM para el mantenimiento (k m ) y la ganancia de peso (kg ) fueron de 0.66±0.023 y 0.42±0.044, respectivamente. Esta revisión también indicó que la información es escasa para ovejas adultas en diferentes etapas fisiológicas (mantenimiento, lactancia y gestación). Se requiere más trabajo de investigación con relación a la estimación de las necesidades de energía de los ovinos de pelo, con el fin de hacer ajustes a los modelos existentes de alimentación, con el objetivo de predecir la respuesta de los animales con la condición que prevalece en los trópicos (tipo de animal, medio ambiente y alimentos disponibles).

O objetivo deste trabalho foi avaliar o desempenho, as características de carcaça e as suas correlações com as expressões gênicas em tourinhos. Quarenta animais Red Norte foram confinados e distribuídos em delineamento inteiramente casualizado, em arranjo fatorial 2x2, e alimentados com grãos de soja moídos ou gordura protegida, com ou sem inclusão de monensina. As dietas foram formuladas para serem isonitrogenadas, com teores de extrato etéreo semelhante (6,5%), e tiveram silagem de milho como volumoso (40%). O período experimental foi de 84 dias, precedido por 14 dias de adaptação. Foram avaliadas as expressões dos genes PPARA, SREBP1c e SCD1. Animais alimentados com gordura protegida tiveram maior ganho de peso nos primeiros 56 dias de confinamento. O uso da monensina não afetou o ganho de peso diário dos animais, mas proporcionou aumento do rendimento de carcaça. Houve correlação de -0,40 entre o ganho de peso dos animais e a expressão do SCD1. O uso de gordura protegida aumenta o desempenho dos animais no início do confinamento, e a monensina proporciona maior rendimento de carcaça.

The objective of this work was to evaluate performance, carcass traits, and their correlation with gene expression in young bulls. Forty Red Norte animals were feedlot and distributed in a completely randomized design, using a 2x2 factorial arrangement, and fed ground soybean grains or rumen-protected fat, with or without monensin supplementation. Diets were formulated to be isonitrogenous, with similar ether extract contents (6.5%), and had corn silage as roughage (40%). The experimental period lasted 84 days, preceded by 14 days of adaptation. The expressions of the PPARA, SREBP1c and SCD1 genes were evaluated. Animals fed rumen-protected fat had greater average daily gain in the first 56 days of feedlot. Monensin did not affect the daily gain, but increased carcass weight. There was -0.40 correlation between animal daily gain and SCD1 expression. The use of rumen-protected fat increases animal performance at the beginning of feedlot, and monensin provides greater carcass weight.

Este trabalho foi realizado com o objetivo de avaliar as características da carcaça em novilhos Zebuínos alimentados com inclusão de fontes de lipídeos moídas. Utilizaram-se 31 novilhos Zebuínos com idade média inicial de 23 meses e peso vivo inicial de 365 + 37,5 kg. As dietas consistiram em silagem de milho e quatro concentrados, sendo um sem lipídeo adicional (SLA) e três com a inclusão de diferentes grãos de oleaginosas moídas: grão de soja (GS), caroço de algodão (CA) e semente de linhaça (SL). As rações apresentaram relação concentrado:volumoso 60:40 e foram fornecidas ad libitum. O período experimental teve duração de 84 dias sendo precedido de um período de adaptação de 28 dias. O delineamento utilizado foi em blocos casualizados, sendo as médias dos tratamentos comparadas pelo teste Scott & Knott no nível de 5% de probabilidade. Com a inclusão de CA observou-se diminuição (p < 0,05) do rendimento de carcaça dos animais. O traseiro especial foi mais pesado (p < 0,05) com a inclusão GS na dieta. O maior rendimento (p < 0,05) da ponta de agulha e maior peso (p < 0,05) de coxão duro foram verificados com a inclusão de CA e SL na dieta. A inclusão de GS na dieta melhora as características de carcaça.

This research aimed to evaluate carcass traits of Zebu steers fed different oleaginous grains. Thirty one 23 months old zebu steers with 365 + 37.5 kg of live weight were used. The diets consisted ofcorn silage and four different concentrates; no additional lipids and three different ground oilseeds sources: soybean, cottonseed and linseed. The diets had concentrate:roughage ratio of 60:40 and were offered ad libitum. The experimental period was of 84 days, preceded by a 28 day adaptation period. The experiment was carried out in a randomized block design and the means were compared by Scott-Knott test at 5% level of probability. The CS inclusion of into the diet decreased (p < 0.05) carcass yield of the animals. The hindquarter was heavier (p < 0.05) with the addition of SB to the diet. The spare ribs had the highest performance (p < 0.05) and outside flat was heavier (p < 0.05) when the animals were submitted to CS and FS diets. The CS addition to the diet improved carcass characteristics.

The objective of this research was to evaluate average daily gain (ADG), carcass traits, meat tenderness and profitability of keeping cattle fed different oilseeds and vitamin E in feedlot. A total of 40 Red Norte young bulls with initial average body weight of 339±15 kg were utilized. The experimental design was completely randomized in a 2 × 2 factorial arrangement. The experiment lasted 84 days and experimental diets presented soybeans or cottonseeds as lipid sources associated or not to daily supplementation of 2,500 UI vitamin E per animal. The concentrate:roughage ratio was 60:40. Diets had the same amount of nitrogen (13% CP) and ether extract (6.5%). The data were analyzed by means of statistical software SAS 9.1. Neither vitamin supplementation nor lipid source affected ADG. There was no interaction between lipid source and vitamin supplementation for the variables studied. The inclusion of cottonseed reduced the carcass yield. There was no effect of diets on hot and cold carcass weights or prime cuts. The inclusion of cottonseed reduced the backfat thickness. No effect of experimental diets on the rib-eye area was observed. There was no effect of lipid source or vitamin supplementation on meat tenderness, which was affected, however, by ageing time. Diets with soybeans presented higher cost per animal. The utilization of soybean implied reduction of the gross margin (R$ 59.17 and R$ 60.51 for diets based on soy with and without supplemental vitamin, respectively, vs. R$ 176.42 and R$ 131.79 for diets based on cottonseed). The utilization of cottonseed enables improvement of profitability of feedlot fattening, in spite of negatively affecting some carcass characteristics.

Objetivou-se com este trabalho avaliar as características de carcaça e o peso dos cortes comerciais da carcaça de tourinhos Red Norte e Nelore terminados em confinamento. Utilizaram-se 44 animais, sendo 22 Red Norte com peso vivo médio inicial de 367±30 kg e 22 Nelore com peso vivo médio inicial de 361±30 kg. Os animais receberam ração à vontade com relação concentrado:volumoso de 50:50 durante 112 dias, sendo 28 dias de adaptação, e foram abatidos aos 519 e 482 kg para Red Norte e Nelore, respectivamente. A espessura de gordura subcutânea (EGS) e a área de olho-de-lombo (AOL) no músculo longissimus dorsi foram medidas entre a 12ªe 13ª costelas. Observou-se maior rendimento de carcaça nos animais Nelore (57,7 vs 54,7%). Entretanto, não houve diferença no peso de carcaça quente e fria entre os grupos. Os animais Red Norte apresentaram maior AOL, maiores pesos e rendimentos de traseiro e ponta-de-agulha, e menor peso e rendimento de dianteiro. O grupo genético Red Norte apresentou maior peso de picanha e contrafilé, enquanto o Nelore apresentou maior peso de paleta e coxão duro. Animais Nelore apresentam maior rendimento de carcaça em relação aos Red Norte, o que favorece o peso de carcaça quente, principal forma de remuneração paga aos produtores. Todavia, animais Red Norte apresentam maior rendimento de traseiro e maior peso dos cortes de maior valor comercial.

The objective of this study was to evaluate the characteristics of carcass and weight of the commercial meat cuts from carcass of Red Norte and Nellore young bulls finished in feedlot. Forty four animals - 22 Red Norte with initial average weight of 367±30 kg and 22 Nellore at initial average weight of 361±30 kg - were used. The animals received feed ad libitum with concentrate:roughage ratio of 50:50 during 112 days, from which 28 days were for adaptation. Red Norte and Nellore animals were slaughtered at 519 and 482 kg, respectively. The subcutaneous fat thickness (FT) and longissimus muscle area (LMA) were measured between 12th and 13th ribs. Higher carcass yield of the Nellore breed was observed (57.7 vs 54.7%). However, there was no difference for weight of hot and cold carcass between the groups. Red Norte animals showed greater LMA, and hindquarter and spare ribs with higher weight and yield, and forequarter with lower weight and yielding. The Red Norte genetic group showed higher weight for cap and rump and striploin, while Nellore showed higher weight for shoulder and flatround. Nellore animals had better carcass yield, which contributes to hot carcass weight. Nevertheless, the group Red Norte have higher hindquarter yield and more weight from cuts of highest commercial value.

Objetivou-se com este trabalho avaliar a composição química e o perfil de ácidos graxos do músculo longissimus dorsi e da gordura subcutânea de tourinhos Red Norte e Nelore terminados em confinamento. Utilizaram-se 44 animais, sendo 22 Red Norte com peso vivo inicial médio de 367±30 kg e 22 do grupo Nelore com peso vivo inicial médio de 361±30 kg. Os animais receberam ração à vontade durante 112 dias e foram abatidos com 519 e 482 kg, respectivamente. Amostras do músculo longissimus dorsi e da gordura subcutânea foram coletadas 24 horas após abate entre a 12ª e 13ª costelas para análise da composição centesimal e do perfil de ácidos graxos. As análises de ácidos graxos foram realizadas por meio de cromatografia gasosa, em coluna capilar de 100 m. Não houve diferença na composição química da carne entre os grupos genéticos. Nos animais Red Norte, foram maiores os teores dos ácidos graxos pentadecanoico, palmítico, palmitoleico, linoleico e ácido linoleico conjugado (CLA), enquanto nos animais Nelore foi encontrado o maior teor de ácido oleico. O músculo longissimus dorsi apresentou maiores teores dos ácidos láurico, heptadecenoico, esteárico, linoleico, α-linolênico e araquidônico. Em comparação ao músculo longissimus dorsi, na gordura subcutânea foram maiores os teores dos ácidos mirístico, miristoleico, pentadecanoico, palmítico, palmitoleico, oleico e CLA. Os animais Red Norte apresentaram maiores teores de ácidos graxos saturados em comparação aos Nelore. Em bovinos, o perfil de ácidos graxos depositados no músculo é diferente do observado na gordura subcutânea. O perfil de ácidos graxos da carne de tourinhos difere entre grupos genéticos.

The objective of this study was to evaluate the chemical composition and the fatty acid profile of the longissimus dorsi muscle and the backfat thickness of Red Norte and Nellore young bulls finished in feedlot. Fourty-four animals (22 Red Norte with initial average weight of 367±30 kg and 22 Nellore at initial average weight of 361±30 kg) were used. The animals were fed ad libitum during 112 days, slaughtered at 519 and 482 kg, respectively. Samples of the longissimus dorsi muscle and backfat thickness were collected 24 hours after slaughter between the 12th and 13th ribs for analysis of the chemical composition and the fatty acids profile. Fatty acid analyses were performed by gas chromatography with a 100-m capillary column. There was no difference for the chemical composition of the meat between the genetic groups. Red Norte animals showed higher contents of pentadecanoic, palmitic, palmitoleic, linoleic and conjugated linoleic acid (CLA) fatty acids, while Nellore animals had the highest content of oleic acid. The muscle longissimus dorsi showed greater concentrations of lauric, heptadecenoic, stearic, linoleic, α-linoleic and arachidonic acids. Comparing the fatty acid deposited in the longissimus dorsi muscle with backfat thickness, the latter showed higher contents of miristic, miristoleic, pentadecanoic, palmitic, palmitoleic, oleic and CLA acids. Red Norte animals showed higher contents of saturated fatty acid than Nellore. In bovine, the profile of fatty acids deposited in the muscle is different than the that in the backfat thickness. The fatty acids profile of the meat from young bulls differs between genetic groups.

The objective of this study was to estimate the urinary creatinine excretion by the shrunk body weight (SBW). In experiment I, 32 Nellore bulls with initial body weight of 259±24.9 kg and 14±1 months-old were used. The group was divided in four animals to maintenance and twenty eight animals feeding ad libitum and separated in four groups; each group was slaughtered at different times of feedlot (42, 84, 126 and 168 days). The diet was composed of corn silage and concentrate (55:45). Before the slaughters, the total urinary collection was realized during three days. A database of creatinine excretion was collected from other five studies that had been conducted with Nellore cattle. In all the studies, the total urinary collection was realized during at least three days. At the end of each collection, the animals were weighted. Urinary creatinine excretion (UCE) was related with the shrunk body weight and it can be estimated by the equation: UCE (g/day) = 0.0345 × SBW0.9491.

Avaliaram-se o consumo, o desempenho e a digestibilidade de dietas contendo diferentes grãos de oleaginosas em novilhos zebuínos em confinamento. Utilizaram-se 30 novilhos zebuínos com peso vivo inicial de 388,0±37,5 kg, distribuídos em delineamento inteiramente casualizado. As dietas foram formuladas com silagem de milho e quatro concentrados: um sem suplementação de lipídeos e três com a inclusão de grão de soja, caroço de algodão ou semente de linhaça. As rações, isonitrogenadas, apresentaram relação concentrado:volumoso 60:40 e foram fornecidas à vontade. Para determinação da digestibilidade aparente total, a produção fecal foi estimada utilizando-se fibra em detergente neutro indigestivel como indicador interno. O menor consumo de matéria seca (7,20 kg/dia) foi observado para a dieta contendo caroço de algodão, mas, entre as outras dietas, não houve diferenças nesta variável. O ganho médio diário foi menor quando se utilizou a dieta contendo caroço de algodão em relação à dieta sem lipídeo (0,93 vs. 1,16 kg/dia, respectivamente). No entanto, não houve diferença no ganho médio diário destas dietas em relação às demais. Houve redução da digestiblidade da fibra em detergente neutro na dieta contendo semente de linhaça. Adicionalmente, houve redução na digestibilidade dos carboidratos não-fibrosos nas dietas contendo caroço de algodão e semente de linhaça em relação à dieta com grão de soja, a qual não diferiu da dieta controle. A inclusão de caroço de algodão moído em dietas para bovinos em confinamento deve ser feita com cautela, pois pode provocar redução no consumo de matéria seca e no ganho médio diário. No entanto, a eficiência alimentar não é afetada pela adição de oleaginosas na dieta de bovinos de corte quando o nível máximo de extrato etéreo na matéria seca total da dieta não excede 6%.

This study was conducted to evaluate feed intake, performance and of digestibility diet containing different oilseeds to beef cattle finished in feedlot. Thirty zebu steers (388.0±37.5 kg of body weight) were used in a completed randomized design. The diets consisted of corn silage and four different concentrates: one without lipids and three with inclusion of soybeans, cottonseed and linseed. The diets, which were isonitrogenous, had roughage:concentrate ratio of 60:40 and were offered ad libitum. To determinate the total apparent digestibility of nutrients, the fecal output was estimated through internal marker indigestible neutral detergent fiber. The lowest dry matter intake was observed for cottonseed (7.20 kg/d), but among the other diets, the dry matter intake did not differ. The average daily gain was lower when cottonseed was used, in comparison with linseed (0.93 vs. 1.16 kg/d, respectively). However, there was no difference on average daily gain in relation to other diets. There was reduction in the digestibility of neutral detergent fiber in linseed diet. Additionally, there was a reduction in the neutral detergent fiber digestibility in diets with cottonseed and linseed compared with soybeans, which did not differ from the control diet. The inclusion of ground cottonseed in feedlot beef cattle diets should be realized with caution, since it can decrease dry matter intake and average daily gain. However, feed efficiency is not affected by the addition of oilseeds in beef cattle diets when the maximum ether extract level in total dry matter diet does not exceed 6%.

The objective of this study was to evaluate the daily intake and total apparent digestibility of dry matter, organic matter, crude protein, gross energy, ether extract, neutral detergent fiber, acid detergent fiber, total and non-fibrous carbohydrates, total digestible nutrients, energy intake and nitrogen balance of silages of six maize varieties with early or super early cycles recommended to Northeast Brazil. Twenty-four male castrated lambs were lodged in metabolic cages. A completely randomized design with six treatments and four replications was used, with means compared by Tukey test at 5%. There were no differences among varieties for any of the evaluated variables regarding intake and apparent digestibility. Concerning the intake of digestible energy, metabolizable energy and the ratio content of digestible and metabolizable energy, significant differences were observed between varieties and BRS Assum Preto showed highest values of metabolizable energy (2.650,8 kcal/day). All of the treatments presented positive nitrogen balance and did not differ among themselves. The varieties asessed can be an additional option to the semiarid regions in Brazil.

Objetivou-se determinar as exigências proteicas de bovinos anelorados, em pastagem com Brachiaria decumbens suplementada com concentrado. Foram utilizados 28 novilhos zebuínos não-castrados com média de 7 meses de idade e 180 kg. Foram abatidos oitos animais-referência para determinação da composição corporal inicial. Os 20 animais restantes foram divididos em cinco lotes de quatro animais, em delineamento inteiramente ao acaso, de modo que cada lote recebeu um dos cinco planos nutricionais: mantença; mistura mineral; e suplementação nos níveis de 0,75; 1,50 e 2,25 kg/animal/dia. A meia-carcaça direita de todos os animais foi dissecada em músculo, gordura e ossos e todos os constituintes do corpo foram pesados para determinação do peso de corpo vazio e da composição corporal. De posse desses dados, procedeu-se ao cálculo das exigências líquidas para ganho de peso em diversas faixas de peso corporal dos animais. Os conteúdos de proteína retidos no corpo dos animais foram regredidos em função do ganho de peso de corpo vazio e da energia retida. As exigências de proteína metabolizável total de um animal de 350 kg e ganho diário de 1,0 kg, foram de 593,59 g/dia. Esse mesmo animal, consumindo 7,40 kg de MS/dia, necessita de dietas com 12,97% de PB na MS total. A exigência líquida de proteína para ganho de peso de animais anelorados não-castrados em pastejo, com até 350 kg de peso corporal, reduzem conforme o peso corporal ou a energia retida aumentam e pode ser estimada a partir da equação: PR (g/dia) = -26,2946 + 247,4853 x GPCVZ - 24,8436 x ER.

The objective of this trial was to determine the protein requirements of Zebu bovines on Brachiaria decumbens Stapf. pasture supplemented with concentrate. It was used 28 non-castrated Zebu steers at an average age of 7 months and 180 kg average weight. Eight baseline animals were slaughtered to determine the initial body composition. The 20 remaining animals were divided in five plots of four animals, in a completely randomized design so each group received one out of the five nutritional plans: maintenance; mineral mix; and supplementation at the levels of 0.75; 1.50 and 2.25 kg/animal/day. In all animals, the right half carcass was dissected in muscle, fat and bones and all the body components were weighed to determine the empty body weight and empty body composition. These data allowed the calculations of net requirements forweight gain in several ranges of the body weight of the animals. Contents of protein withheld in the bodies of the animals were regressed in function of empty body gain and withheld energy. The requirements of total metabolizable protein for an animal with 350 kg and average daily weight gain of 1.0 kg, were 593.59 g/day. That same animal, consuming 7.40 kg of DM/day requires diets with 12.97% of CP in total DM. The net requirement of protein for weight gain of non-castrated grazing Zebu bulls with up to 350 kg of body weight decreases as the body weight or retained energy increases, and it can be estimated by the equation: PR (g/day) = -26.2946 + 247.4853 x GPCVZ - 24.8436 x ER.

Objetivou-se desenvolver e avaliar novas equações para predição do consumo de matéria seca (CMS) em bovinos Nelore e mestiço, utilizando-se meta-análise. Os dados utilizados para estimar os parâmetros foram coletados em experimentos de desempenho independentes com bovinos Nelore e mestiço nas fases de recria e engorda, compilados a partir de 561 unidades experimentais. Antes de propor uma equação para predizer o CMS, observou-se que o grupo genético foi uma fonte de variação estatisticamente significativa. Neste sentido, equações para predizer o CMS em bovinos Nelores e mestiços foram desenvolvidas de forma independente. As equações de regressão para bovinos mestiços foram: CMS = -2,6098 + 0,08844PV0,75 + 4,4672GMD - 1,3579GMD2 e CMS = -1,0094 + 0,01608PV + 4,4363GMD -1.2548GMD2. As equações de regressão para bovinos Nelore foram: CMS = -2,7878 + 0,08789PV0,75 + 5,0487GMD - 1,6835GMD2 e CMS = -1,3559 +,0159PV + 5,6397GMD - 1,8494GMD2. Para avaliar as equações ajustadas, utilizaram-se dados de experimentos independentes publicados entre 2005 e 2008 na Revista Brasileira de Zootecnia. As equações (CMS) para Nelore superestimaram o CMS para estimativas menores que 7 e maiores que 10 kg d-1. Para bovinos mestiços, as dispersões de 3 kg·d-1 foram observadas quando pontos extremos foram avaliados, no entanto, quando a equação incluiu PV0,75, o intercepto não diferiu de zero e a inclinação não diferiu de 1. Não é possível ajustar uma única equação para predizer o CMS para bovinos de corte em condições tropicais, porque há diferenças entre Nelores e mestiços. Equações ajustadas que incluem GMD e PV0,75 devem ser usadas como um método alternativo para predizer o CMS em bovinos Nelores e mestiços em condições tropicais.

The study was carried out to develop and to evaluate new equations to predict dry matter intake (DMI) of Nellore and Zebu-crosses cattle using meta-analysis procedure. The data used to estimate the parameters were collected from independent performance experiments using growing and fattening Nellore and Zebu-crosses cattle, and they were compiled from 561 experimental units. Before proposing an equation to predict DMI, it was observed that the genetic group was a source of statisticaly significant variation. Therefore, equations to predict dry matter intake in the Zebu-Crosses and Nellore cattle were independently developed. The regression equations for Zebu-crosses cattle were: DMI = -2.6098 + 0.08844BW0.75 + 4.4672ADG - 1.3579ADG2 and DMI = -1.0094 + 0.01608BW + 4.4363ADG -1.2548ADG2. The regression equations for Nellore cattle were: DMI = -2.7878 + 0.08789BW0.75 + 5.0487ADG - 1.6835ADG2 and DMI = -1.3559 + 0.0159BW + 5.6397ADG - 1.8494ADG2. In order to evaluate fitted equations, it was utilized data from independent experiments published from 2005 to 2008 in the Revista Brasileira de Zootecnia. The equations (DMI) for Nellore overpredicted dry matter intake for estimates lower than 7 and higher than 10 kg·d-1. For Zebu-crosses cattle, dispersions of 3 kg d-1 were observed when extreme intakes were evaluated, however, when the equation included BW 0.75, the intercept did not differ from zero and the slope did not differ from 1. It is not possible to fit only one equation for preditcting DMI for beef cattle in tropical conditions, because there are differences between Zebu and Zebu-crosses. Fitted equations that include ADG and BW 0.75 should be used as an alternative method to predict dry matter intake of Zebu-crosses and Nellore beef cattle in tropical conditions.

A água é um nutriente extremamente importante na vida dos animais e deve ser considerada como vital em qualquer fase da criação. A escassez crescente deste precioso recurso natural tem provocado reações de diferentes segmentos da sociedade na busca de soluções de uso racional e sustentável deste nutriente. Os pequenos ruminantes, especialmente os ovinos e caprinos, são partes importantes da vida econômica e social de muitas nações pela sua ampla capacidade de adaptação às condições adversas do ambiente e boa eficiência no uso da água, podendo ser uma das boas alternativas de mitigação dos efeitos das mudanças climáticas, gerando divisas e melhoria das condições de vida em muitas regiões do mundo. O conceito de produtividade de água para a produção animal é relativamente novo e ainda são recentes e escassos os estudos existentes no mundo e em particular no Brasil. A realização de mais pesquisas e a geração de novas tecnologias de uso da água na produção animal, hoje mais do que nunca tornam-se imprescindíveis.

Water is a nutrient of extreme importance for animals and must be considered vital in any rearing phase. The increasing scarcity of this precious natural resource has concerned different segments of society in order to find solutions for rational and sustainable use of this nutrient. Small ruminants, especially sheep and goats, have social and economic importance due to their great ability in adapting to adverse environmental conditions and using water efficiently. Thus, they might be a good alternative to mitigate the climate change effects and to generate foreign exchange and improving life condition in many places of the world. The concept of water productivity for livestock production is relatively new and there are few studies in the world, especially in Brazil. More researches and new technologies for water use in livestock production are indispensable.