EFFECTS OF FEEDING A HIGH-GRAIN LACTATION PERFORMANCE AND REBREEDING OF EWES

Fifty-six mature Polypay ewes were used in two experiments to examine the effects of feeding a high-grain diet at a restricted intake on mil k production and composition lamb performance and out-of-season breedi ng. Ewes were fed either a high-grain diet (85% concentrate and 15% fo rage) or a high-forage diet. The high-forage diets were 68% forage and 32% concentrate in Experiment 1 and 80% forage and 20% concentrate in Experiment 2. Forage source was orchardgrass hay (Experiment 1) or al falfa cubes (Experiment 2). Feed intake of the high-grain diet was res tricted by 20% (compared with ewes fed high forage) so that intake of energy was similar for both dietary groups. Daily milk production was 19% higher (P < .05) in Exp. 1 and 8% higher (P < .10) in Exp. 2 for e wes fed high grain than for those fed high forage (2.71 vs 2.28 kg/d a nd 3.18 vs 2.95 kg/d in Exp. 1 and 2, respectively). Milk protein perc entage and daily amount of milk protein were higher (P < .05) and the percentage of milk fat was lower (P < .03) for ewes fed the high-grain diet than for those fed the high-forage diet. Diet did not affect mil k fat production (grams/day) or lamb growth rate. In both experiments blood insulin concentration was higher for ewes fed the high-grain die t than for those fed the high-forage diet; however, no improvements in reproductive performance were observed. Limit feeding high-grain diet s is an effective alternative to forage for lactating ewes.