Concentrate with calcium salts of fatty acids increases the concentration of polyunsaturated fatty acids in milk produced by dairy goats

Abstract

Feeding rumen-inert fat, such as calcium salts of fatty acids (CSFA), has dual benefits as it increases milk yield and improves the fat composition in milk. However, there is a shortage of information on the effect of CSFA on milk yield and composition in grassland Saanen goats. Thus, this study aimed to evaluate the effects of CSFA in the concentrate of lactating grassland Saanen goats on milk yield, composition, quality, and fatty acid composition and to determine the best response to the addition of CSFA. Five multiparous Saanen goats (five years old) were distributed in a 5×5 Latin square design with five treatments (0%, 1.5%, 3.0%, 4.5% and 6.0% CSFA), and four primiparous Saanen goats (three years old) were distributed in a 4×4 Latin square design with four treatments (0%, 1.5%, 3.0% and 4.5% of CSFA); the goats had an average of 78±10 days in lactation at the start of the experiment. Each period lasted 21 days, including 14 days for adaptation and seven days for data collection. Pelleted concentrate was composed of ground corn, soybean meal, a mineral–vitamin supplement for goats, salt and CSFA at the levels of inclusion. For grazing goats, an area with Stargrass (Cynodon nlemfuensis) was used. The addition of CSFA to the concentrate of grassland Saanen goats had no effect on milk yield, milk components such as fat, protein, lactose and totals solids, or milk quality (acidity and somatic cell counts) in multiparous or primiparous goats. However, the concentration of fatty acids was modified. The concentration of capric (10:0) and myristic (14:0) fatty acids decreased linearly with increased inclusion of CSFA in the concentrate. There was a quadratic effect on medium-chain and long-chain fatty acids and omega-3 (n-3) in the milk of multiparous Saanen goats following treatment. The inclusion of CSFA in the diet of primiparous goats had a positive linear effect for linoleic fatty acid (18:2 n6c), conjugated linoleic acid, omega-6 (n-6) and polyunsaturated fatty acids, whereas the concentration of medium-chain fatty acids showed a negative linear effect. In conclusion, CSFA in the concentrate of grassland primiparous goats showed positive responses on the fatty acid composition of goat milk, increasing the polyunsaturated fatty acid concentration.