Use of Different Dietary Protein Sources for Lactating Goats: Milk Production and Composition as Functions of Protein Degradability and Amino Acid Composition

Abstract

To establish the effect of the nature of four different protein sources [fababeans, 27.8% crude protein (CP); sunflower meal, 41.7% CP; corn gluten feed, 18.8% CP; and cottonseed, 18.3% CP] on milk protein production by goats, the ruminal degradation of these feeds was studied as was the amino acid (AA) composition of the original material and that of the undegradable fractions of the protein sources. Four diets were designed; 20% of their protein was supplied by each of the different sources. Four groups of 5 Granadina goats were used to study the utilization of these diets for milk production. No significant differences were observed in dry matter intake or milk production. The milk produced by goats fed the diet containing sunflower meal had the lowest protein concentration; the highest milk protein concentration was observed for goats fed the diet containing corn gluten feed. From a multivariate analysis, it was deduced that the quickly degradable protein fraction in the rumen and the ruminally undegradable protein fraction were the components of the protein sources most directly related to the milk protein produced. Given the similar AA profiles of the undegradable fractions of the different protein sources, the possible supplementation achieved from these ruminally undegradable fractions must be established by the amount of protein supplied regardless of AA composition.

Nutritive evaluation of legume seeds for ruminant feeding

“…Previous studies concerning rumen degradability of legume seeds are scarce, with the exception for lupin (Aufrère et al., 2001; Remond et al., 2003; Solanas et al., 2005) and, to a lesser extent for beans (Cros et al., 1992b; Goelema et al., 1998; Sanz Sampelayo et al., 1999). The available information indicates high variability, which can be ascribed in part to methodological differences such as animals and feeding conditions, bag pore size, rumen outflow rate used, sample preparation etc.…”

Características físico-químicas e custo do leite de cabras alimentadas com farelo de cacau ou torta de dendê

“…Segundo Sauvant et al (1987), citados por Sampelayo et al (1998), desde que a relação volumoso:concentrado não seja menor que 20:80, o equilíbrio de energia do animal é mais importante na determinação do conteúdo da gordura do leite que a proporção. O alto consumo de carboidratos não fibrosos poderia ter promovido diminuição da porcentagem de gordura do leite, em razão de o produto final da fermentação desses carboidartos serem os ácidos propiônico ou láctico.…”

“…Esses valores mais baixos devem-se ao menor teor de gordura. Os conteúdos em extratos secos totais e desengordurados parecem não sofrer influência de diferentes fontes protéicas (Sampelayo et al, 1999), no entanto acompanham as variações do teor de gordura e da densidade (Bonassi et al, 1997). Os valores de densidade específica (Tab.…”

Milk production of dairy goats fed diets with different legume seeds: Effects of amino acid composition of the rumen undegradable protein fraction

“…To determine the overall changes in the AA composition of the different legume seeds arising from ruminal incubation, a multivariate factorial analysis was performed3, 5 using the factor procedure of SAS;8 the algorithm used was PRO FACTOR. The correlation matrix was selected.…”

“…Systems currently in use to estimate the protein value of feedstuffs for ruminants distinguish between the dietary protein fraction, which after ruminal degradation yields microbial protein, and the fraction that escapes ruminal fermentation and reaches the small intestine 2. At the same time, the importance of the amino acid (AA) profile of the rumen undegradable protein fraction of the protein sources has been stressed 3–5…”