Apparent digestibility coefficients of rations containing alfalfa hay and rhodes grass hay for growing mares

Abstract

This work was conducted at the "UEPAE-São Carlos - EMBRAPA", to study the replacement of alfalfa hay (Medicago sativa L.) for Rhodes grass hay (Chloris gayana Kunth) based on the dry matter and nutrient digestibility coefficients in rations for growing mares. Twelve mares of the "Arabic Breed" and twelve of the "Mangalarga Breed" were used, averaging 21 months of age and weighting 296 kg. The animals (four of each breed) were randomly alloted into three treatments: R1 - 60% concentrate, 40% Rhodes grass hay; R2 - 60% concentrate, 20% alfalfa hay, 20% Rhodes grass hay; R3 - 60% concentrate, 40% alfalfa hay. The concentrate (about 20% crude protein) was made of 40% corn (with husks and cobs), 40% cotton seed meal and 20% wheat bran. The rations were offered in three meals daily: 8:00 AM, 1:00 PM and 5: 00 PM. The apparent digestibility coefficients were estimated with the aid of chromic oxide (10/g/head/day). Feces were collected from the rectum of the animals at 9:00 AM and 6:00 PM, for seven consecutive days. The comparisions among the treatment means were analysed by the "Tukey" test. The apparent digestibility coefficients obtained for treatments R1, R2 and R3 were, respectively: Dry matter (71,39%, 73,04%,73,45%); crude protein (83,32%,85,70% 86,49%); crude fiber (56,47%. 56,09%, 50,18%); ether extract (68,81%, 69,56%,53,20%) and nitrogen free extract (76,38%, 77;76%, 79,89%). Although the crude protein, crude fiber, ether extract and nitrogen free extract digestibility coefficients for treatment R3 were statistically different (P <.01) from the other two, the results suggest that Rhodes grass hay can replace alfalfa hay in rations for growing mares, without any detrimental effects on the animals.