title: Effects of feeding a high-grain diet at a restricted intake on lactation performance and rebreeding of ewes.
abstract: 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 milk production and composition, lamb performance and out-of-season breeding. Ewes were fed either a high-grain diet (85% concentrate and 15% forage) 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 forage and 20% concentrate in Experiment 2. Forage source was orchardgrass hay (Experiment 1) or alfalfa cubes (Experiment 2). Feed intake of the high-grain diet was restricted 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 ewes fed high grain than for those fed high forage (2.71 vs 2.28 kg/d and 3.18 vs 2.95 kg/d in Exp. 1 and 2, respectively). Milk protein percentage 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 milk fat production (grams/day) or lamb growth rate. In both experiments blood insulin concentration was higher for ewes fed the high-grain diet than for those fed the high-forage diet; however, no improvements in reproductive performance were observed. Limit feeding high-grain diets is an effective alternative to forage for lactating ewes.
authors.affiliation: Department of Animal Sciences, Ohio Agricultural Research and Development Center, Wooster, USA.
authors.forename: I
authors.initials: I
authors.lastname: Susin
authors.forename: S C
authors.initials: SC
authors.lastname: Loerch
authors.forename: K E
authors.initials: KE
authors.lastname: McClure
mesh_terms: D000821:Animal Feed / Q000592:standards; D000818:Animals; D001947:Breeding; D004032:Diet / Q000592:standards / Q000662:veterinary*; D004435:Eating / Q000502:physiology; D002523:Edible Grain / Q000592:standards; D005260:Female; D005527:Food, Fortified; D007328:Insulin / Q000097:blood; D007774:Lactation / Q000502:physiology*; D000455:Medicago sativa / Q000592:standards; D008892:Milk / Q000378:metabolism; D011247:Pregnancy; D018873:Pregnancy Rate; D012098:Reproduction / Q000502:physiology*; D012756:Sheep / Q000378:metabolism / Q000502:physiology*
chemical_list: D007328:Insulin