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Improving Sow Productivity through Management during Gestation, Lactation and after Weaning^1,2,

North Carolina State University³, Raleigh 27695-7621

Abstract

Number of pigs produced per sow per year is dependent upon the number of pigs born live, the number that survive to weaning and the interval between consecutive farrowings for the sow. Feeding and management of the sow during late gestation affects birth weight and amount of energy stored as glycogen and lipid in the piglet. Piglets that are heavier and that have more energy stores have a higher survival rate. Adding fat to the sow's diet during the last month of gestation or altering the sow's metabolism to direct more nutrients to the fetus are methods for increasing piglet birthweight and energy stores. Feeding the sow properly during lactation is important for maximum yield of milk and milk energy, which affects survival of pigs to weaning, and for rebreed-ing performance of the sow after weaning. Energy intake during lactation can be increased by adding fat to diets, and this is beneficial in situations where feed intake is insufficient to meet the sow's requirements. For example, fat supplementation during lactation is beneficial for primi-parous sows and for sows lactating during hot weather. The minimum practical lactation length is about 2 wk for normal rebreeding performance of the sow. Split weaning or separation of the litter from the sow for 6 to 12 h/d will shorten the rebreeding interval or induce estrus during lactation. Administration of pregnant mare's serum gonadotropin, with or without human chorionic gonadotropin, will induce estrus during lactation, and the response is better after the second week of lactation. Similar treatments at weaning will shorten the rebreeding interval. Scheduling boar use so sufficient sperm are in each ejaculate and mating once daily during estrus will maximize conception rate and subsequent litter size. Culling of sows has minor effects on sow productivity except in extreme situations where culling rates are below 30 or above 70%.

¹ Paper No. 10138 of the Journal Series of the North Carolina Agr. Res. Serv., Raleigh, NC 27695-7601. The use of trade names in this publication does not imply endorsement by the North Carolina Agr. Res. Serv. of the products named, nor criticism of similar ones not mentioned. Some of the research from the author's laboratory presented in this paper was supported by grants from the North Carolina Pork Producers Assoc., the Natl. Pork Producers Council and USDA grant 82-CRSR-2-1069.

² Presented at the Nonruminant Nutrition Symp. entitled "Increasing Sow Efficiency" at the 77th Annu. Meet., of the Amer. Soc. of Anim. Sci., August 14, 1985, Univ. of Georgia, Athens.

³ Box 7621, Dept. of Anim. Sci.