Effect of increased postmilking prolactin concentrations on lactation, plasma metabolites, and pancreatic hormones in lactating goats.
Six lactating dairy goats were utilized in a replicated 3 x 3 Latin square design to examine the effect of increased postmilking prolactin concentrations on lactational performance. Thirty minutes after each milking, either placebo or pituitary-derived ovine prolactin at 2 mg/h or 4 mg/h was infused via jugular cannula for 2 h. Goats were housed in a controlled environment at 19 degrees C and a cycle of 16 h light and 8 h dark. Mean plasma prolactin concentrations after milking were increased 100 and 180% for 2 and 4 mg/h prolactin infusion, respectively. Milk yield was slightly but significantly increased by 2 mg/h prolactin infusion compared with placebo and 4 mg/h prolactin infusion. However, milk composition and yields of milk components were not influenced by treatments. No differences in dry matter intake, digestibility of the diet, or N retention were observed. Circulating concentrations of glucose, nonesterified fatty acids, insulin, and glucagon were not altered.
Jacquemet
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Division of Animal and Veterinary Sciences, West Virginia University, Morgantown 26506-6108.
Prigge
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EC
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D004063:Digestion / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D006041:Goats / Q000097:blood / Q000502:physiology*; D007328:Insulin / Q000097:blood; D007774:Lactation / Q000187:drug effects* / Q000502:physiology; D008892:Milk / Q000737:chemistry / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010187:Pancreatic Hormones / Q000097:blood*; D011388:Prolactin / Q000097:blood / Q000494:pharmacology*
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D010187:Pancreatic Hormones; D011388:Prolactin; D005934:Glucagon; D009584:Nitrogen