The aim of this study was to investigate the possibility of improving the composition of goat meat, in terms of the fatty acid composition of the different fat deposits. For this purpose, we used two groups of 12 female goats each of which had recently undergone a double birth. The animals were maintained under semi-extensive conditions and trough-fed with a concentrate that was either non-supplemented or supplemented with 50 g/kg of polyunsaturated fatty acids (PUFA)-rich fat protected against ruminant metabolism. The kid goats born to each group were suckled by their dams and a representative sample of each was slaughtered at 45 days after birth. The milk produced by the dams receiving the fat-supplemented diet contained fat with a lower content of saturated fatty acids and a higher content of n-3 PUFA, trans-C18: 1 and CLA. The kid goats suckled by these dams grew faster and the legs of the carcasses presented greater muscular development compared with the non-fat-supplemented diet group. The cover, intermuscular and intramuscular fat presented a different fatty acid composition, with a higher proportion of n-3 PUFA, trans C18: 1 and CLA, while that of n-6 PUFA remained unchanged. The change in the lipid metabolism of the kid goats was made evident by the blood levels of certain biochemical parameters. We discuss the improvement in the quality of the meat obtained, taking into account the feeding strategy provided and the class of animal in question.

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.

Two groups of six male goats were used to assess the effects of rumen-protected supplements offish oil on intake, digestibility and nitrogen (N) balance. The animals were offered a diet consisting of forage and concentrate, the latter fraction supplemented with 0 (control) or lOOg/kg of rumen-protected fish oil supplement (PFO), containing a high proportion of the n-3 series (whole diet contained 0 or 60 g PFO per kg dry matter). No significant differences (P > 0.05) were found between the two groups concerning live-weight gain, food intake, digestibility of DM, organic matter, N, neutral-detergent fibre and energy. In contrast, there were differences (P < 0.05) regarding the digestibility of fat and of acid-detergent fibre, which were higher among the animals given the PFO diet. With respect to the individual fatty acids, we observed higher digestibility (P < 0.05) of C14:0, C16:0, C18:0 and C20:0 among the animals given the PFO diet. The digestibility of C14:0, C18:0 and C20:0 was found to be negative among the animals given the control diet. No significant differences (P > 0-05) were found regarding digestibility of total C18:1. In contrast, the coefficients for C18:2 (n-6) and C18:3 (n-3) were higher (P < 0.05) among the non-supplemented animals. The intake and faecal flow values of C18:0 suggest that the mono- and polyunsaturated fatty acids with 18 atoms of carbon may, in both cases, undergo partial hydrogenation, which would be greater among the control group. The utilization of C20:5 (n-3) and, especially, of C22 : 6 (n-3), which were consumed only by the animals given the PFO diet, was estimated at 1-000. The PFO diet also produced lower levels ofurinary-N excretion (P < 0.05), giving rise to higher N balances (P < 0.05).