INTAKE AND DIGESTIBILITY OF CORN, RYE AND SORGHUM-SUDAN GRASS SILAGES BY LACTATING COWS

Abstract

Eighteen lactating Holsteins were utilized in a 3 × 3 Latin square (49 d treatment −1 ) for a comparative estimation of the intake and digestibility of corn, rye and sorghum-sudan grass silages. The dry matter (DM), protein and acid detergent fiber contents were 32.5, 8.0, 27.0; 25.2, 8.7, 45.6 and 22.4, 10.6, 40.7 percent for corn, rye, and sorghum-sudan silages, respectively. Dry matter intake of the silage and milk yield were less (P < 0.05) for cows fed rye silage compared to those fed corn and sorghum-sudan grass silage. Cows lost body weight when fed rye silage but gained weight when fed either corn or sorghum-sudan grass silage. The feeding of rye silage resulted in a decrease (P < 0.05) in milk protein percent compared to the feeding of corn or sorghum-sudan silage and in the percentage of milk lactose compared to the feeding of sorghum-sudan grass silage. Molar proportions of rumen acetate were higher (P < 0.05) when cows were fed either rye or sorghum-sudan silage compared to corn silage. Cows fed rye silage had higher molar proportions of rumen propionate and valerate and lower levels of butyrate (P < 0.05) compared to cows consuming sorghum-sudan silage. The digestibility of total ration DM was lower (P < 0.05) when either rye or sorghum-sudan silage was the forage portion of the ration compared to corn. It was concluded from this trial that sorghum-sudan silage provided a suitable source of forage for lactating dairy cows. However, the DM intake and milk yield of cows fed rye silage was less than satisfactory. Key words: Dairy cattle, rye, sorghum-sudan, silage, intake, digestibility