Suplementação nitrogenada e níveis de concentrado para vacas mestiças leiteiras a pasto no período de transição águas-seca

• Autor(a) principal: Gutierrez, Gabriela Santistevan
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5809
• topic: Bovino de leite - Alimentação e rações; Brachiaria decumbens; Bovine milk - Food and feed; Brachiaria decumbens; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The objective of this research was to evaluate the effect of nitrogenous supplementation and two levels of concentrate feeds on dry matter intake and digestibility, milk production and composition, feed efficiency, balance of nitrogenous compounds and microbial protein synthesis in lactating crossbred cows (1/2 Holstein x Zebu) grazing Brachiaria decumbens pastures during the transition period rainy-dry season. Eight crossbred cows with average body weight of 497 ± 50 kg, between the third and fourth lactations and after lactation peak were used. The cows were distributed according to a balanced 4 x 4 Latin square design, with two simultaneous squares in a factorial design of 2 x 2, being used two types of supplements, nitrogenous salt and mineral salt ad-libitum and two concentrate levels in the diet (1.5 and 3.0 kg/cow/day), based on 60% corn meal and 40% of soybean meal given during the two milking times, in the morning and afternoon. The experiment lasted 56 days, which were divided into four experimental periods of 14 days each, being seven days for adaptation and the other for data collection. No significant interaction (P>0.05) was observed between the supplements and the different concentrate levels for any of the evaluated variables. The nitrogenous salt and the higher concentrate level increased (P<0.05) the consumption of crude protein and the higher concentrate level increased (P<0.05) the intake of non-fibrous carbohydrates. The digestibility of crude protein increased (P<0.05) with the higher concentrate level. No significant effect (P>0.05) of supplement or concentrate level was observed with the characteristics of urinary excretions, nitrogenous compounds nor microbial efficiency. Nitrogenous salt increased (P<0.05) the consumption of nitrogen and increased the urinary excretion, leading to reduced nitrogen balance, while the high concentrate level feeds increased (P<0.05) nitrogen consumption and total nitrogen excretion through milk. No significant effect (P>0.05) of supplement and concentrate level was observed on the milk components (protein, lactose, total solids and non fat solids) and feed efficiency (kg milk/kg of DMI). Grazing crossbred cows in mid lactation during the transition period of rainy-dry season achieve their productive potential with 1.5 kilograms of concentrate per day, neither being necessary higher concentrate level nor nitrogenous salt.