Resumo A desmama precoce (DP) vem sendo adotada nas fazendas de cria do Pantanal como alternativa para o aumento dos índices de concepção das vacas. A principal receita dessas propriedades são os bezerros (as), sendo o seu valor dependente dos seus respectivos pesos. Assim é necessário que os bezerros submetidos à DP, apresentem pesos semelhantes ou acima dos bezerros desmamados convencionalmente. Desta forma o estudo teve como objetivo, acompanhar o desempenho de bezerros nascidos no Pantanal, submetidos à DP ou a desmama convencional (DC), puros (Nelore) ou Cruzados (Nelore/Angus). Após a DP os animais receberam suplemento específico para bezerros, na quantidade fixa de 1 kg/animal/dia (baixa energia) ou ao nível de 1% do Peso Vivo (alta energia). Os pesos ajustados aos 300 dias de idade foram maiores para os bezerros de DP sob alta energia (P<0,01), em ambos os grupos genéticos. Os pesos dos animais de DP de baixa energia e de DC, não se diferiram (P>0,01), sendo de 241,17 e 236,27 kg para o grupo de bezerros Cruzados e de 184,44 e 189,78 para o grupo de bezerros Nelore respectivamente. A DP adotada no modelo experimental não prejudicou o desempenho dos bezerros nascidos no Pantanal.

Abstract Early weaning (EW) has been adopted in cattle breeding farms in Pantanal as a strategy to increase the rate of pregnancy in cows. The primary income of these properties is the production of beef calves, and the price of these animals depends on their weight. Therefore, the calves subjected to EW should present weight similar to or higher than those of calves subjected to conventional weaning (CW). This study aimed to evaluate the productive performance of pure (Nellore) calves and crossbred (Nellore/Angus) calves reared in the Pantanal and subjected to either EW or CW. After EW, the calves were supplemented with concentrate at 1 kg/animal/day (low-energy diet) or 1% of live weight (high-energy diet). The weights adjusted to 300 days of age were higher for EW calves fed the high-energy diet (p<0.01) in both genetic groups. No significant differences were observed in the weight of EW animals fed the low-energy diet and CW animals (p>0.01), and animal weight was 241.17 and 236.27 kg in crossbred calves and 184.44 and 189.78 in Nellore calves, respectively. The EW adopted in this experimental model did not affect the productive performance of calves raised in the Pantanal.

RESUMO Objetivou-se avaliar o efeito de dois teores de proteína bruta no suplemento mineralnitrogenado para terminação de novilhos Nelore. Foram utilizados 90 animais, com peso médio inicial de 382,35±32,95 kg, submetidos a dois tratamentos: suplemento com 30% de proteína bruta (75% de milho, 8,91% ureia e 16,09% mineral) e 40% de proteína bruta (66,67% de milho, 11,90 % ureia e 21,43% mineral). Os animais foram mantidos em dois piquetes de Uruchloa brizantha cv. MG-5 (sin. Brachiaria brizantha). Foram realizadas pesagens ao início, aos 45 e aos 94 dias de experimento, quando foram abatidos com 451,1±35,38 kg. Foi avaliado o consumo de suplemento, o ganho de peso e variáveis econômicas. Houve efeito do tratamento sobre o consumo de suplemento (P<0,05), com médias de 0,69±0,21 (40% PB) e 2,26±0,52 (30% PB) kg/dia. A média de ganho de peso total foi superior (P<0,01) para os animais que receberam suplemento com 30 % PB (71,46 vs 64,33 kg/animal). Foi obtido maior peso de abate nos animais do tratamento com 30% PB (456,66 vs. 443,84 kg). Em ambos tratamentos, o desempenho e as caracteristicas de carcaça foram satisfatórios. Sob o ponto de vista econômico, recomenda-se a suplementação com 40 % PB na terminação de novilhos em pastagens, porém o sucesso para redução dos custos de produção no campo depende das variações entre as cotações nas diferentes regiões do país e mercado de oportunidades.

SUMMARY The objective of this study was to evaluate the effects of two protein levels in mineral-protein-energy supplements on the productivity and economic performance of Nellore steers. Ninety animals weighing 382.35±32.95 kg on average, were treated with mineral-nitrogen supplements containing 30% crude proteins (CP; 75% ground maize, 8.91 % urea and 16.09% mineral) and 40% CP (66.67 % ground maize, 11.90% urea, and 21.43% mineral). The animals were housed in two paddocks of Uruchloa brizantha ‘MG-5’ (syn. Brachiaria brizantha) and were weighed at the beginning, at 45 days, and at 94 days of the experiment, when they were slaughtered at an average weight of 451±35.38 kg. We evaluated supplement intake, weight gain and economic aspects. The 40 and 30% CP treatments significantly affected supplement intake (P<0.05), with averages of 0.69 and 2.26 kg/day, respectively. The average total weight gain was higher (P<0.01) in animals receiving the supplement containing 30 % CP (71.46 kg / animal) than in animals receiving 40% CP (64.33 kg/animal). Greater slaughter weight was attained in the animals treated with 30% CP (456.66 vs. 443.84 kg). The mineral-nitrogen supplementation in both CP levels provided satisfactory animal performance and carcass characteristics. Owing to economic considerations, it is recommended to use 40% CP mineral-nitrogen supplements on finishing steers on pasture, although success in reducing production costs of livestock ultimately depends on the variations in prices between the different regions of the country and market opportunities.

RESUMO Objetivou-se avaliar a terminação de novilhos Nelore, castrados e não castrados, em confinamento recebendo dieta alto grão, por meio do consumo de nutrientes, desempenho produtivo e viabilidade econômica da dieta. Foram utilizados 180 animais da raça Nelore, distribuídos em dois tratamentos (castrados e não castrados), com 90 animais por tratamento, com peso médio inicial de 415,64kg, recebendo dieta alto grão, constituída de 85% de milho grão e 15% de núcleo mineral-proteico-energético. O período experimental foi de 63 dias, sendo 15 dias para adaptação as dietas e 48 dias de confinamento. Houve efeito significativo para os consumos de nutrientes (P<0,05), apresentando médias de consumos de matéria seca de 7,60 e 7,96kg para animais castrados e não castrados. Houve efeito para as variáveis de desempenho produtivo em função da classe sexual (castrado e não castrado). Os animais não castrados apresentaram maiores (P<0,05) peso de abate, ganho de peso, peso de carcaça quente, rendimento de carcaça e melhor conversão alimentar quando comparados aos animais castrados terminados em confinamento recebendo dieta alto grão. Os animais castrados apresentaram maior espessura de gordura que os animais não castrados, de 4,80 e 3,40mm, respectivamente. Os animais não castrados apresentaram margem de lucro/animal de R$ 256,00 e os castrados de R$ 202,80. Recomenda-se a terminação de novilhos Nelore em confinamento recebendo dieta alto grão. Os animais não castrados apresentaram maior ganho de peso e lucro no sistema de terminação em confinamento recebendo dieta alto grão.

SUMMARY This study aimed to evaluate the finishing Nellore steers castrated and no-castrated in feedlot receiving high-grain diet through the nutrients intake, productive performance and economic viability of the diet. 180 Nellore animals were divided into two treatments (castrated and no-castrated), with 90 animals per treatments, with an average initial weight of 415.64kg, receiving high-grain diet with 85% corn grain and 15% supplement mineral-protein-energy. The experimental period was 63 days with 15 days for adaptation diets and 48 days of feedlot. Was no significant effect on intake of nutrients (P<0.05), presenting a mean intake of dry matter (DM) of 7.60 and 7.96kg for castrated and no-castrated. Effects were observed for productive performance as a function of sex condition (castrated and no-castrated). The not castrated animals had higher (P<0.05) slaughter weight, total weight gain, hot carcass weight, carcass yield and better feed conversion when compared to castrated animals finished in feedlot receiving high-grain diet. Castrated animals have a higher fat thickness that animals no-castrated, 4.80 and 3.40mm, respectively. The no-castrated animals showed profit margin lucre/animal of R$ 256.00 and R$ 202.80 for castrated. Receiving the termination of Nellore steers in a feedlot is recommended high-grain diet. The no-castrated animals showed greater weight gain and profit in the feedlot finishing system receiving high-grain diet.

The objective was to evaluate the effect of weight, age and production efficiency of cows from genetic groups based on the calf weight at calving and at weaning. For a period of five years, data of 120 cows (60 Angus-Nellore (AN) and 60 Simmental-Nellore (SN)) at four to nine-years of age were evaluated. All cows were maintained on Brachiaria decumbens pastures, with two forage availability levels (high and low), distributed in a randomized-block design. The cows were placed together with Canchim bulls to generate the crossbred calves. A supplement, consisting of 200 g/kg crude protein and 820 g/kg of total digestible nutrients, was provided to the calves in creep feeding until 210 days-old (weaning). Supplement had a significant effect on the weight of the cow at calving and weaning. The average weights of the Angus-Nellore cows were 529.19 and 514.23 kg at calving and on the weaning day, respectively. These values were higher for Simmental-Nellore cows, which presented 569.60 and 542.59 kg, respectively. The male-calf weight at weaning was 254.69 kg, which was higher than the females (237.70 kg). Genetic group had no effect on weaning weight. The average weight for Canchim × Angus-Nellore calves was 243.41 kg and for Canchim × Simmental-Nellore it was 248.98 kg. Cow age affected weaning weight, promoting a linear increase of 0.804 kg in the weaning weight each year. Younger and smaller cows (Angus-Nellore) are more efficient for calf production.

The objective of this experiment was to evaluate the effects of replacing eCG with FSH or FSH/LH on the diameter of ovulatory follicles (DOF) and the pregnancy rates (PR) of lactating Bos indicus cows subjected to a synchronization of ovulation protocol and fixed-time artificial insemination (FTAI) based on progesterone, estradiol benzoate (EB), PGF2α, and estradiol cypionate (EC). On day 0, primiparous and multiparous Nellore cows (n = 329) at 68 days postpartum were body condition scored (BCS) and received a P4 implant (PRIMER 1.0 g P4) plus 2 mg EB intramuscularly (IM). At day 8, the implant was removed, and 250 μg cloprostenol were injected IM along with 0.5 mg EC. At the time of implant removal, the animals were divided into one of four treatments: cows received (G1) 1 mL of saline solution IM (Control; n = 80); (G2) 300 IU eCG IM (ECG300; n = 84); (G3) 15 mg FSH IM (Folltropin; n = 82); and (G4) 30 IU FSH/LH IM (Pluset; n = 83); all cows were subjected to FTAI 48-54 h after implant removal (day 10). Transrectal ultrasonography was performed to measure the DOF to FTAI and to estimate the pregnancy rate on day 35. A statistical analysis examined the effects of the treatment, technician, semen, BCS, calf age and parity on PR to FTAI. There was no significant difference in PR and DOF among the treatment groups (G1, 41.3%, 13.1 mm; G2, 46.4%, 14.5 mm; G3, 46.3%, 14.2 mm; and G4, 48.2%, 14.3 mm), but PR was higher in multiparous than in primiparous cows. Commercial FSH solutions (Pluset or Folltropin) do not promote increases in PR or DOF of lactating Nellore cows and are equal to eCG in promoting growth in preovulatory follicles and elevating the PR in Nellore cows with a moderate BCS subjected to a progesterone-based FTAI protocol with EC.

O trabalho foi conduzido com objetivo de avaliar dois protocolos de sincronização de cio em receptoras de embriões sobre a taxa de aproveitamento ao longo do ano, bem como os custos e as características reprodutivas dos animais sincronizados. Os tratamentos foram: T1: sincronização para transferência em tempo fixo com utilização de implantes de progesterona e estradiol, e T2: sincronização com aplicação de prostaglandina e observação de cio. Foram sincronizadas 2947 receptoras de embriões, e a taxa de aproveitamento foi de 83,24% no tratamento 1, e 60,73% no tratamento 2. Os corpos lúteos foram avaliados no dia da inovulação de embriões, obtendo-se 63,73% da ovulação no ovário direito. As taxas de aproveitamento não apresentaram diferenças entre os meses do ano (P>0,05). O protocolo em tempo fixo apresentou custo mais elevado (US$ 10,51 vs 2,03) que a utilização de prostaglandinas e observação de cio, no entanto a taxa de aproveitamento de receptoras foi maior. As taxas de aproveitamento das receptoras não variam ao longo do ano, quando atendidas as condições de nutrição e manejo adequados para receptoras de embrião bovino.

The study was conducted to evaluate two protocols for synchronization of estrus in embryo recipients on the utilization rate throughout the year, as well as costs and the reproductive characteristics of synchronized animals. The treatments were: syncronization to transfer fixed-time with the use of implants of progesterone and oestradiol, and synchronization with prostaglandin and heat detection. 2947 embryo recipients were synchronized, and the rate of utilization was 83.24% in treatments 1 and 60.73% in treatments 2. The corpus luteum were evaluated on the day of embryo transfer, yielding 63.73% of ovulation in the right ovary. The utilization rate did not differ among months. The protocol at fixed time showed higher cost (U.S. $ 10.51 vs 2.03) than the use of prostaglandins and heat detection, but the utilization rate was higher . The utilization rates of the recipients do not vary throughout the year, when observing the conditions of nutrition and appropriate management for bovine embryo recipients.

To verify the effects of energy supplementation and fat on follicular dynamics, metabolic profile and the production of oocytes, 15 young heifers (Bos taurus indicus) with an average age of 14 months and with an initial weight of 256.35 kg were assigned to two treatments according to weight and follicular population as evaluated by ultrasonography: in T1 (1.0 × M), animals received 100% of the energy requirements for maintenance; in T2 (1.7 × M), animals received 170% of the energy requirements for maintenance, achieved by the addition of 200 g of Megalac®. After a period of adaptation to the diet, the treatments, blood collection and follicular aspirations were started using a randomized design. The dry matter intake and weight gain were lower in the 1.0 × M group than in the 1.7 × M group. No differences were found in the plasma progesterone concentrations, albumin, glucose, urea or gonadotropin (FSH and LH) levels between the groups. The mean concentrations of cholesterol were higher in the 1.7 × M group. The total number of small (<4 mm) and medium follicles (4-8 mm) was not altered by the treatments, but the number of small follicles increased on days 1 and 2 of the estrous cycle, with higher values found in the 1.7 × M group. The average of the oocytes also increased (9.50±2.1 and 12.5±4.4 for the 1.0 × M and 1.7 × M groups, respectively). The rapid increase in the amount of energy offered in the diet changes the amount of follicles and oocytes available for follicular aspiration (OPU) in young heifers without changing their metabolic profile.

The objective of this study was to evaluate pregnancy rates of recipients of different breed groups (Nellore and crossbreed), as well as the effects of size and type of the corpus luteum (CL) on plasmatic concentrations of progesterone and pregnancy rates of embryo recipients. A total of 152 heifers were synchronized with progesterone implants and on the day of embryo transfer, previously obtained by superovulation and frozen in ethylene glycol, the diameter and type of the corpus luteum (cavitary and compact) was measured and blood was collected for progesterone measurement. The pregnancy rate was 44.1%, with a diameter of corpus luteum higher in recipients that became pregnant (2.03±0.41) compared with non-pregnant ones (1.86±0.34 cm). Plasmatic concentrations of progesterone did not differ between pregnant (1.50±1.05) and non-pregnant (1.31±0.91 ng/mL) animals. The type of corpus luteum did not influence the pregnancy rates. Only Angus and crossbred Marchigiana differ among themselves in pregnancy rates (33.3 and 59.2%, respectively). The pregnancy probability was affected only by CL diameter, but not by P4 plasmatic concentration. Selection of the corpus luteum size at the time of embryo transfer is an important factor to increase pregnancy rates in recipients, and compact and cavitary corpora lutea do not influence the pregnancy rates of bovine embryo recipients. Nellore recipients have pregnancy rates that are satisfactory and comparable to crossbred (Bos taurus × Bos indicus) recipients.

The objective of this study was to evaluate the administration of different doses of calcium hydroxide mixed with sugar cane fed to cows by the pH, ammonia nitrogen and volatile fatty acids concentration in ruminal content. Four cows with fistulated rumen were distributed in a Latin square (4 × 4) in split plot. The treatments involved adding doses of 0, 8, 16 and 24 g/kg of calcium hydroxide to sugar cane in natura. Samples of rumen fluid were collected and the pH and concentration of N-NH3 was determined before (time zero) and 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 hours after the feeding time. The concentration of volatile fatty acids at 0, 3, 6, 9 and 12 hours was also determined. The calcium hydroxide contributed to maintain the pH of rumen fluid close to neutral. The average concentrations of N-NH3 in the ruminal fluid was 20.59, 20.49, 17.28 and 18.22 mg/100 mL for samples with calcium hydroxide at 0, 8, 16, 24 g/kg, respectively. There was an effect of the addition of calcium hydroxide on the volatile fatty acids concentration from before feeding until 12 hours after feeding time. There was an effect on doses tested for the concentration of volatile fatty acids. The calcium hydroxide added to the sugar cane influences on ruminal parameters. The dose of approximately 10 g of calcium hydroxide per kg sugar cane in natura is recommended.

O objetivo deste trabalho foi avaliar o desempenho reprodutivo de vacas Nelore em pastos de capim-marandu, após a retirada do fosfato bicálcico da mistura mineral, na estação seca. Sessenta matrizes receberam, durante seis anos, mistura mineral completa na estação chuvosa. Na estação seca, os tratamentos consistiram de: mistura mineral completa (MMC); MMC sem fosfato bicálcico (MM); e MM + concentrado. As pastagens foram manejadas de forma a não limitar a disponibilidade de matéria seca. A retirada do fosfato bicálcico do suplemento mineral, durante a estação seca, não prejudicou o desempenho reprodutivo de vacas, avaliado pela taxa de prenhez, intervalo de partos e retorno da atividade cíclica ovariana. Vacas que receberam concentrado na estação seca pariram em melhor condição corporal; vacas primíparas arraçoadas apresentaram menor número de dias vazios do que as vacas primíparas dos demais tratamentos. A retirada do fosfato bicálcico suplementar, fonte de fósforo e cálcio, na estação seca, não prejudica o desempenho de vacas multíparas em pastejo de capim-marandu.

The objective of this work was to evaluate the reproductive performance of Nelore cows at 'Marandu' palisade grass paddocks, after dicalcium phosphate withdrawal from the mineral supplement in the dry season. Sixty breeding cows received, during six years, a complete mineral mixture in the wet season. In the dry season, the treatments consisted of: a complete mineral mixture (MMC); MMC without dicalcium phosphate (MM); and MM plus a concentrate. Pastures were managed in order to allow for adequate dry matter availability. The removal of dicalcium phosphate from the mineral supplement, during the dry season, did not affect the animal reproduction performance which was evaluated as pregnancy rates, delivery intervals and return of oestrous cycles. Cows receiving concentrate in the dry season had higher body score at delivery; primiparous cows which fed concentrate showed a lower number of days open, in comparison to the primiparous ones of the other treatments. Dicalcium phosphate withdrawal from the mineral supplement, source of phosphorus and calcium, during the dry season, does not affect the reproductive performance of multiparous range cows grazing 'Marandu' palisade grass.

The objective of this work was to evaluate, in bovines, the intake and apparent digestibility of nutrients, ingestive behaviour and content of total digestible nutrients (TDN) of diets based on sugar cane treated with calcium hydroxide. It was used four cows with average body weight of 412.06 kg ± 37.3 kg. The study included inclusion of calcium hydroxide at the doses 0, 8, 16 and 24 g/kg of sugar cane in natural matter basis fed in diets with 65% of roughage and 35% on concentrate, based on dry matter (DM). It was used a 4 × 4 Latin square experimental design with four treatments and four periods. Calcium hydroxide doses affected nutrient intake: DM intake was 7.88 kg/day at the dose of 14.99 g of calcium hydroxide, organic matter (OM) intake was 6.75 kg/day at 10.94 g; intake of neutral detergent fiber (NDF) of 3.33 kg/day with a dose of 13.93 g; and intake of acid detergent fiber (ADF) of 2.12 kg/day with a dose of 10.51 g. Digestibility coefficients showed a quadratic effect for doses of inclusion of calcium hydroxide. Dry matter digestibility was 72.88% with a dose of 11.65 g of calcium hydroxide, OM digestibility was 75.12% with 12.09 g; NDF digestibility was 58.67% with 12.11 g; ADF digestibility was 52.97% with 9.36 g and TDN digestibility was 71.42% with 10.92 g. There was no effect of the treatment for activities of rumination and total idle. Chewing time, number of bolus chewed and time for rumination of each bolli presented effect. Calcium hydroxide enabled greater intakes and digestibility of nutrients, especially from the cell wall, favoring the use of nutrients from the diet containing sugar cane, recommending a dose of 8-12 g.

Grande parte dos problemas do rebanho de cria, incluindo baixa taxa de prenhez e baixos pesos à desmama, está diretamente relacionada ao consumo inadequado de energia e/ou proteína, ou a deficiências de minerais e vitaminas. Procurou-se estudar o efeito da suplementação de cálcio e fósforo, com ou sem proteína e energia, sobre o desempenho produtivo de vacas de cria em pastagem de B. brizantha cv. Marandu, durante a seca. Todas as fêmeas receberam mistura mineral completa nas águas; na seca, os tratamentos foram: mistura mineral completa, mistura mineral sem fosfato bicálcico com ou sem concentrado protéico-energético. Nas condições deste trabalho, a suplementação protéico-energética não teve efeitos significativos sobre o ganho de peso e a condição corporal das vacas, bem como sobre o peso dos bezerros ao parto e à desmama. O intervalo entre partos não diferiu entre os tratamentos, mas as vacas primíparas que receberam ração apresentaram menor número de dias vazios. A ausência de suplementação de P durante o período seco não acarretou prejuízos significativos nas taxas reprodutivas dos animais. Os efeitos de tratamento foram minimizados pelas boas condições das pastagens.

Many problems of the beef herd, including low pregnancy rates and low weaning weights, are related to inadequate intakes of energy and /or protein, as well as to minerals and vitamins deficiencies. The objective of the present study was to evaluate the performance of beef cows supplemented with phosphorus/calcium with or without energy/protein during the dry season. All cows received complete mineral mixtures during the wet season; during the dry season, the imposed treatments were: complete mineral mixtures or mineral mixtures lacking dicalcium phosphate, supplemented or not with concentrate. In the present conditions, protein/energy supplement showed no significant effects on weight gains and body condition of cows, as well as on calf weight at calving and at weaning. The calving interval did not differ between treatments, but primiparous heifers that received concentrate exhibited less open days. Phosphorus supplementation during the dry season did not affect negatively reproductive performance. The treatment effects were minimised by the good pasture condition.