Effects of the level of supplementation with concentrate on the nutritive value and utilization of oats hay cut at three maturity stages

Abstract

Abstract A digestion trial was conducted to study the effects of stage of maturity of oats hay as well as the effects of concentrate supplementation on its nutritive value. Hay was cut at 3 stages of maturity: milky, dough and hard grain. The 3 forages were fed associated to 4 levels of concentrate 0, 20, 40 or 60% giving 12 diets. These diets were fed to 9 rams. The results show that the 3 stages of maturity of hays studied had small differences in chemical composition and digestibility and low crude protein content which did not reach 4%. The only difference in digestibility was observed for crude protein which was lower for the dough stage compared to the other 2 stages. However the effect of stage of maturity was significant for intake and substitution rate. In fact, the hard grain stage had a lower intake and a higher substitution rate than the other 2 stages. The values for hay intake were 1124 g/d for the milky stage versus 1009 g/d for hard grain stage. DM, OM and crude protein digestibilities of the ration increased with increasing level of concentrate. However digestibility of the fiber fractions (ADF and crude fiber) increased slightly with the low level of supplementation (20%), but decreased with higher levels (40 and 60%). For the whole ration, intake increased with the level of supplementation up to 40%, however, there was a tendancy for its stabilization at levels over 40%. The substitution rate of hay by concentrate increased with increasing level of concentrate in the ration regardless of the stage of maturity. Positive digestive interactions of 2.3 and 1.5 points were observed between concentrate and hay at the milky and dough stages, while a negative interaction of 0.6 points was observed between concentrate and hay at the hard grain stage.