Can maintenance intake reduce production costs without compromising the reproductive performance in bucks?

Excessive intake of nutrients can result in decreases in the reproductive efficiency of goat bucks and increase production costs in goat e nterprises. In this study, the aim was to compare the reproductive features of young bucks fed diets for maintenance of growth or were fed ad libitum. Ten bucks were used (n = 5/group), with a completely randomized design. Blood and semen were collected from each animal every 2 weeks for nine collections. Semen was frozen and later analyzed using flow cytometry to compare reactive oxygen species, plasma membrane integrity, acrosome integrity, and membrane lipid peroxidation. Body condition score, sexual behavior, testicular biometry and histomorphometry of the testis, as well as oxidative enzymes and carbonylated proteins, were also evaluated. Animals fed ad libitum had a greater body condition score (3.32 + 0.08 × 2.88 + 0.05), sperm volume (0.68 + 0.04 × 0.52 + 0.03 mL), and testis circumference (25.2 + 0.21 × 24.5 + 0.24 cm) and volume (121 + 5.83 × 107 + 4.38 cm³, left testicle; 116 + 5.26 × 100 + 3.75 cm³, right testicle). Ejaculates of the bucks fed diets to maintain growth rate had a larger number of minor and total sperm morphology defects. There were no differences in testosterone concentrations and sexual behavior. In conclusion, there can be feeding for growth rate maintenance instead of ad libitum feeding, for the reduction in production costs of young bucks without compromising semen quality and reproductive functions.

Degradação ruminal da silagem de capim-elefante aditivado com cana-de-açúcar e farelo de cacau / Ruminal degradation of elephant grass sillage added with sugarcane and cocoa meal

Objetivou-se avaliar a degradação ruminal da matéria seca (MS), da proteína bruta (PB) e da fibra em detergente neutro (FDN) das silagens de capim-elefante; capim-elefante ensilado com 30 por cento de cana-de-açúcar; 15 por cento de farelo de cacau; e 45 por cento de cana mais 15 por cento de farelo de cacau. Amostras de cada silagem foram incubadas no rúmen de três novilhos mestiços holandês x zebu durante os períodos de 0, 12, 24, 48, 72 e 96 horas. O delineamento experimental utilizado foi o de parcelas subdivididas e os coeficientes não lineares a, b e c foram estimados por meio de procedimentos iterativos de Gauss-Newton. Para o capim-elefante ensilado com farelo de cacau, foram observados maiores valores da fração a da MS e da PB, próximos a 60 por cento, além de maiores taxas da degradação da fração b e da degradabilidade efetiva (DE) da PB para as taxas de passagem 2, 5 e 8 por cento h-1. As silagens que apresentaram as maiores frações não-degradáveis i da FDN foram as silagens de capim-elefante sem aditivo e com 30 por cento de cana, enquanto a silagem aditivada com 45 por cento de cana e 15 por cento de farelo de cacau destacou-se pela maior degradação potencial da MS, da PB e da FDN, em todos os períodos estudados, e maiores DE da MS e da PB para as taxas de passagem 2, 5 e 8 por cento h-1. A inclusão associada da cana-de-açúcar com o farelo de cacau, no momento da ensilagem do capim-elefante, apresenta-se como alternativa para aumentar a degradabilidade da forragem em estádio de crescimento avançado.

The objective was to evaluate the dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) ruminal degradation of silages of elephant grass; elephant grass ensiled with 30 percent of sugarcane; 15 percent of cocoa meal; and 45 percent of sugarcane plus 15 percent of cocoa meal. Samples of each silage were incubated in the rumen of three Holstein x Zebu crossbred steers during the periods of 0, 12, 24, 48, 72 and 96 hours. The experimental design used was the one of subdivided parcels and the non linear coefficients a, b and c were estimated through Gauss-Newton interactive procedures. For the elephant grass ensiled with cocoa meal, larger values of DM and CP fraction a were observed, next to 60 percent, besides the greatest b fraction degradation rates and effective degradability (ED) of CP to passage rates of 2, 5 and 8 percent h-1. The silages that showed the largest non-degradable i fractions of NDF were the elephant grass silages without additive and with 30 percent of sugarcane, while the silage addicted with 45 percent of sugarcane and 15 percent of cocoa meal showed up by the largest DM, CP and NDF potential degradation in all of the studied periods, and larger DM and CP ED for passage rates of 2, 5 and 8 percent h-1. The associated inclusion of sugarcane with cocoa meal at the moment of the elephant grass ensilage comes as an alternative to increase the degradability of forage in advanced growth stage.