No abstract

New highly productive guineagrass (Megathyrsus maximus syn. Panicum maximum) cultivars have been released in Brazil and grazing trials are necessary to evaluate their carrying capacity and forage quality. The objective of this study was to evaluate the liveweight gains of young Nellore bulls grazing 3 guineagrass cultivars under rotational stocking. The experiment was carried out in Planaltina (Federal District, Brazil) during a single rainy (November‒April) and dry (May‒August) season. Treatments were Massai (control), BRS Tamani and BRS Zuri cultivars. Zuri and Tamani pastures provided greater average daily liveweight gains (ADG) (0.38 and 0.42 kg/head, respectively) over the experimental period than Massai (0.28 kg/head). For all cultivars liveweight gains decreased markedly from May onwards at the beginning of the dry season. Nevertheless, bulls grazing Tamani and Zuri pastures still gained 0.20 kg/hd/d until late August, while those on Massai pastures gained only 0.08 kg/hd/d. The differences in ADGs can be explained to some extent by differences in quality of available forage. In vitro dry matter digestibility of plucked samples of Massai was 555 g/kg, compared with 621 g/kg for Tamani and 590 g/kg for Zuri. Crude protein concentration in plucked samples was also greater for Tamani and Zuri (71.9 and 74.2 g/kg, respectively) than for Massai (62.2 g/kg). As feed wastage was particularly high in Massai, further studies are needed to verify if higher stocking rates during the wet season could result in greater production of live weight per ha on this cultivar, assuming that ADG does not decrease further with the increased stocking rate.

No abstract

The objective of this work was to determine the effect of two different feeding plans on quantity and quality of oocytes and in vitro embryo production, as well as on the body development of prepubertal Nellore heifers. After weaning, thirty-three Nellore heifers were divided into two experimental groups and supplemented with two nutritional plans according to dry and rainy seasons. For nutritional plan 2 the animals received diets containing 26% and 19% more metabolizable energy (ME) related to NP1 in the dry and rainy seasons, respectively. After 3.5 months of supplementation (i.e., at 10 months old), animals from both groups underwent follicular aspiration (OPU) every 21 days and in vitro produced embryos (IEP). Withers height, chest depth and body weight of all animals were measured monthly. Subcutaneous fat deposition was measured at the end of the study by ultrasonography. The number of retrieved COCs per OPU and viable oocytes was respectively 49% and 42% greater in NP2 heifers (p=0.018 and p=0.049). Regarding the blastocysts rate, heifers administered NP2 produced 29.7% of blastocysts, a percentage higher than NP1 treatment animals that produced 24.40% of embryos (p<0.05). Consequently, the females from NP2 treatment presented a greater final weight, chest depth, carcass finish, in addition to a greater accumulation of subcutaneous fat. These results indicating a positive effect of diet slightly higher in energy in the assisted reproduction of Nellore prepubertal heifers and also on weight gain and fat deposition in the carcass, allowing these females to reach the suggested early mating conditions.

RESUMO O milho é a principal fonte de energia nas dietas animais. Em algumas regiões brasileiras, sua disponibilidade, principalmente na entressafra, é insuficiente para atender à demanda, fazendo com que seu preço se eleve. Neste estudo, objetivou-se avaliar a substituição do milho pelo sorgo sobre o desempenho zootécnico e a digestibilidade em coelhos. Foram utilizados 60 animais machos da raça Nova Zelândia Branco, divididos em três tratamentos: ração base milho (TM); ração base sorgo (TS) e ração base 50% de milho + 50% de sorgo (TMS). No ensaio de desempenho, avaliou-se ganho de peso (GP), consumo de ração (CR), conversão alimentar (CA), coeficientes de digestibilidade da matéria seca (CDMS), proteína bruta (CDPB), fibra em detergente neutro (CDFDN) e fibra em detergente ácido (CDFDA). Observou-se que o CRM, a CA e o GPM não foram afetados pela substituição do milho pelo sorgo, nos níveis de 50% e 100%. Os resultados de digestibilidade demonstraram maiores CDPB e CDFDN na ração base milho, não havendo diferenças entre os demais parâmetros estudados. O sorgo com baixo teor de tanino pode ser usado nas rações de crescimento de coelhos em níveis de substituição de 50% ou 100% da participação do milho, sem prejuízos para o desempenho zootécnico e a digestibilidade.