The effects of the forage: Concentrate level, grain source and fish oil use in rations on milk yield and composition in lactating goats

Present thesis was conducted to determine the effects of ration, roughage: concentrate feed ratio, cereal sources and oil sources on performance, milk composition, milk fatty acid profile in dairy goats; rumen pH, rumen volatile fatty acids and biohydrogenization of volatile fatty acids of cannulated goats. Different roughage ratios (60, 40), starch (barley, corn) and oil sources (palm, fish) were used in set of four experiments. It was observed in the first and second experiments that dairy goat performance was not influenced by ration treatments. In the first experiments, fish oil in rations reduced milk fat contents, urea, density and saturated fatty acids (SFA) levels; increased conjugated linoleic acid (CLA), C18:1t, eicosapentaenoic acid (EPA) and docosahekzaenoic acid (DHA) and polyunsaturated fatty acids (PUFA). Increasing roughage ratios also increased milk CLA, C18:1t, DHA and reduced EPA. In the second experiments, barley in rations increased milk urea, citric acid, CLA and C18:1t; fish oil in rations altered fat, lactose, acidity, citric acid and density, increased CLA, C18:1t, EPA, DHA and PUFA. In the third experiments, rumen pH, acetate, butyrate was not influenced from the treatments; fish oil in rations reduced rumen propionate, biohydrogenization and increased unsaturated fatty acid ratios; increasing roughage ratios also increased trans fatty acid ratios. In the fourth experiments, corn in rations, increased propionate, acetate/propionate and acetate + butyrate/propionate ratios. Fish oil in rations reduced rumen propionate and biohydrogenization of fatty acids. Corn in rations also reduced biohydrogenization. Along with the present findings, barley grain is recommended as a starch source and fish oil is recommended as an oil source to improve fatty acid composition (CLA, EPA, DHA and PUFA) of goat milk. Roughage ratio should also be increased to improve such fatty acids except for CLA. Key words: Goat milk, fatty acid, biohydrogenization, fish oil, roughage ratio, starch source