Composition and Technological Quality of Malagueña Goat Milk. Effect of Genotype for Synthesis of αs1-Casein in Milk and Protein Content in the Diet

Abstract

The aim of this study was to identify the possible interaction between protein content in the diet and animal genotype, with respect to its higher or lower capability to synthesis α S1-casein in milk, in relation to the production, composition, and technological quality of the goat milk. Twenty-five goats of the Malagueña breed were used, with 13 of them belonging to genotypes with a high capability for synthesis of αS1-casein, and 12 belonging to genotypes with a low capability. The protein content in the diets were: 136 (D1) and 177 (D2) g/kg dry matter. Within each group, a milk production assay was conducted using the two different diets in a two-period balanced changeover design. Within each period, half of the animals consumed the D1 and the other half consumed the D2 diet. According to the results obtained it is deduced the change from D1 to D2 can be considered positive. In the low capability animals, this change would lead to the production of a greater amount of milk. In those with a high capability, this change would either give rise to the production of a greater amount of milk or to the production of a similar amount of milk but one presenting a higher αS1-casein content and, therefore, a milk with better technological quality.

Effect of αs1-casein (CSN1S1) genotype on milk CSN1S1 content in Malagueña and Murciano-Granadina goats

“…The relative importance of environmental and genetic non-additive factors in determining milk CSN1S1 concentration has been consistently evidenced by estimating the heritability of this phenotype in goats (h 2 =0·10, Benradi, 2007) and sheep (h 2 =0·21, Othmane et al 2002). Moreover, the existence of a significant influence of nutrition on CSN1S1 genotype expression, in the Malagueña breed, has been recently evidenced by De la Torre et al (2007), convincingly illustrating the notable complexity of CSN1S1 synthesis regulation.…”

Effect ofCSN1S1gene polymorphism and stage of lactation on milk yield and composition of extensively reared goats

“…The AF and BF goats, showing a lower α s1 -CN content, had an increased production of α s2 , β and κ-CN, indicating a partial compensation of the casein production attributable to these casein fractions, as already evidenced in previous studies (Grosclaude & Martin, 1997; Devold et al 2010). α s1 and α s2 -CN content were independent of lactation stage, while β and κ-CN increased throughout lactation, indicating that the differential expression of the four casein genes is controlled by complex genetic and environmental factors, which are, in this case, only partially known (Caravaca et al 2008; De la Torre et al 2007).…”