INFLUENCE OF THE LEGUME LEUCAENA-LEUCOCEPHALA AND FORMAL CASEIN ON THE PRODUCTION AND COMPOSITION OF MILK FROM GRAZING COWS

Twenty.four lactating Jersey cows, grazing a 3.week regrowth of nitrogen.fertilized Chloris gayana cv. Pioneer pastures selected a diet containing 18 crude protein and were given 0, 2 or 4 kg/day of fresh Leucaena leucocephala or 250 g/day of formal.casein. The effect of the treatments on milk production was measured in a 4 x 4 latin.square design experiment with experimental periods of 14 days.Mean milk yield of unsupplemented cows was 9.6 kg/day, 10.1 kg/day when cows were supplemented with formal.casein and 10.3 kg/day when fed 2 or 4 kg Leucaena/ day. Yields of solids.not.fat, protein, casein, butterfat and short and medium.chain (C4.Cle) fatty acids in milk fat were higher when cows were fed supplements (P<0.01). Intake of digestible organic matter was lowest on the unsupplemented diets although feed in excess of 40 kg D.M./cow/day was offered and cows had little difficulty harvesting feed with a mean bite size of 350 mg organic matter/bite and mean grazing time of 507 min/24 h.It was concluded that a tropical grass diet containing 18 crude protein was deficient in protein for lactating cows and that small quantities of the legume Leucaena can alleviate such a deficiency. © 1979, Cambridge University Press. All rights reserved.