Produção de leite em cabras alimentadas com diferentes níveis de proteína na dieta: consumo e digestibilidade dos nutrientes

Abstract

Produção de leite em cabras alimentadas com diferentes níveis de proteína na dieta: consumo e digestibilidade dos nutrientes 1RESUMO -Avaliaram-se os consumos e as digestibilidades dos nutrientes e a produção e composição do leite de cabras alimentadas com dietas com 47% de silagem de milho e 53% de concentrado, contendo níveis crescentes de PB (11,5; 13,5; 15,5 e 17,5%PB na MS). Foram utilizadas 12 cabras da raça Alpina em lactação, distribuídas em três quadrados latinos 4 x 4, compostos de quatro períodos de 15 dias (sete de adaptação às dietas e oito para coletas de amostras). Amostras de fezes e de leite foram analisadas e os resultados avaliados por meio de análises de variância e regressão. Os consumos de MS, MO, PB, PDR e NDT, assim com as digestibilidades da MS, MO, PB e CNF, aumentaram linearmente com os níveis de PB da dieta. A produção de leite aumentou linearmente com o incremento do nível dietético de PB, enquanto a produção de leite corrigida para 3,5% de gordura e as porcentagens de gordura e PB no leite não foram influenciadas pelos níveis de PB nas dietas. Concluiu-se que os níveis de 13,5% de PB ou 290 g de PB/dia atendem às exigências de proteína e parecem adequados para cabras com produção diária de até 2,7 kg de leite corrigido para 3,5% de gordura.Palavras-chave: alimentação, caprinos, farelo de soja, lactação ABSTRACT -Intake, apparent digestibility of nutrients, milk yield and milk composition were all evaluated in goats receiving diets with 47% of corn silage and 53% of concentrate. Dietary crude protein (CP) was increased as follows [dry matter (DM) basis]:11.5, 13.5, 15.5 and 17.5%. Twelve lactating Alpine goats were randomly assigned to three 4 x 4 Latin squares with 15 days experimental periods: seven days for diet adaptation and eight days for samples collection. Total collection of feces was done from day 8 to day 12 of each period while milk samples on day 10. Data were evaluated by analysis of variance and regression. Intakes of DM, organic matter (OM), CP, rumen degradable protein (RDP) and total digestible nutrients (TDN) increased linearly with the increment of dietary CP. Similarly, digestibilities of DM, OM, CP and non-fiber carbohydrates (NFC) increased linearly when the CP level increased from 11.5 to 17.5 of the diet. Milk production also increased linearly with the increase of CP in the diet but no significant effects were observed for 3.5% fat corrected (FCM) milk as well as for contents of milk fat and milk CP. It can be concluded that the diet with 13.5% of CP met the protein requirements of lactating goats and appeared to be adequate for animals yielding up to 2.7 kg of 3.5% FCM per day.

Performance of dairy goats fed diets with dry yeast from sugar cane as protein source

“…There were no differences (P>0.05) between diets as to total carbohydrates intake (Table 3), and the average value was similar to the observed by Fonseca et al (2006) in dairy goats (1.38 kg/day) that were fed diets with protein levels.…”

Crude protein levels in diets containing pelleted concentrate for lactating goats: intake, digestibility, milk production and composition

“…The nitrogen use efficiency decreased linearly, probably because the higher the crude protein intake, the lower the nitrogen use efficiency for milk production, which agrees with the results obtained by Pereira et al (2005), Fonseca et al (2006) and Paiva (2009). Thus, the nitrogen fraction is not totally used for milk production, probably being directed to other routes of use and/or excretion.…”

“…The best explanation for this is the dilution effect of the increased volume of milk produced, provided by the diets with higher levels of CP. The evident positive effect of CP level of diet on milk fat concentration was possibly due to the increasing activity of fibrolytic bacteria, leading to variation in milk fat between 2.8% and 3.3%, similar to those obtained by other authors (ZAMBOM et al, 2005;FONSECA et al, 2006;RODRIGUES et al, 2007;QUEIROGA et al, 2007 reported values of 3.31%, 2.8%, 2.9 % and 3.4%, respectively. Although it is common that the low forage: concentrate ratio and the shortage of physically effective fiber provide a decrease in the concentration of fat in milk as a consequence of the reduced ruminal pH, increase in rate of passage and decreased use of fiber, it was not found in the present study.…”

Consumo, digestibilidade e produção de leite de cabras leiteiras alimentadas com dietas contendo diferentes níveis de proteína bruta e energia líquida

“…A quantidade de nitrogênio (N), representada pela concentração de N e pelo perfil de degradação ruminal da fonte de N, a sincronização entre a degradação de proteína e a disponibilidade de energia podem influenciar a produção de leite, os teores de gordura e proteína do leite (Lucci, 1997;Wu & Satter, 2000), as características ruminais (pH, AGV, amônia) e as características plasmáticas, como glicose, uréia e ácidos graxos não-esterificados (AGNE) (Imaizumi et al, 2000;Oliveira Jr. et al, 2000;Broderick, 2003).…”