Growth of pre-ruminant kid goats and the composition of carcass fat deposits: Effects of providing a PUFA-rich fat in the milk replacer and influence of the kidding season

Abstract

The aim of this study is to investigate the possibility of improving the composition of goat meat in terms overall, of the fatty acid composition of different fat deposits. The experiment is designed in an 2 × 2 factorial arrangement. The treatments consist of two different milk replacers, one including and one excluding 2% of fish oil, and two different kidding seasons (spring or autumn). Twelve animals are allocated at random, to each treatment. Animals are slaughtered when they reached a body weight of 7000 ± 200 g. The inclusion of fish oil has no significant effect on growth rate, food efficiency ratio or dressing percentage. The cover, intermuscular and intramuscular fat of the leg from the animals fed with the milk replacer including fish oil, present higher and lower proportions of n-3 PUFA and saturated fatty acids respectively, while that of n-6 PUFA remains unchanged. The inclusion of fish oil in the milk replacer increases the 20 : 5 content in the leg muscle from about 0.4 to 3.5% and 22: 6 content from 0.4 to 2.3%. The fatty acids 20: 5 and 22: 6 are also detected in the cover and intermuscular fat when fish oil is included in the diet. The kid goats born in autumn, show a higher birth weight and growth rate. The leg obtained from these animals, presents a higher proportion of muscle and a lower proportion of bone. However, in the animals born in spring, a somewhat more favourable composition is obtained in the leg fat deposits. The improvement in the quality of meat obtained is discussed, taking into account the feeding strategy provided and the class of animals in question.