Phosphate supplementation withdrawal during dry season for Nelore range cows

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

DESEMPENHO DE BEZERROS SUBMETIDOS A DESMAMA PRECOCE NO PANTANAL

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 (P0,01), 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.Palavras-chave: Nutrição, bezerros de corte, suplementação

Follicular dynamics and production of oocytes in young Nellore heifers with energetic supplementation

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

Efficiency of calf production of cows from two genetic groups

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