Kim S W, Osaka I, Hurley W L, Easter R A
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
J Anim Sci. 1999 Dec;77(12):3316-21. doi: 10.2527/1999.77123316x.
Twenty-eight primiparous sows were used to determine the effect of litter size on the growth of mammary glands and nursing pigs during lactation. Litter size was set to 6, 7, 8, 9, 10, 11, or 12 pigs by cross-fostering immediately after birth. Four sows were allotted to each litter-size group. Sows were allowed to consume a daily maximum of 13.6 Mcal ME and 46.3 g of lysine during lactation. Sows were slaughtered on d 21 (20.6+/-1.1) of lactation. Mammary glands were collected at slaughter and trimmed of skin and the extraneous fat pad. Each gland was separated, weighed, and ground for chemical analysis. Dry matter, dry fat-free tissue (DFFT), crude protein, ash, and DNA contents were measured. Only glands known to have been nursed were included in the data set. Wet and dry weights and the amounts of DFFT, protein, DNA, ash, and fat in individual nursed mammary glands linearly decreased (P<.05) as litter size increased. Percentages of DFFT, protein, and DNA were quadratically affected (P<.05) by litter size on d 21 of lactation. Total mammary wet and dry weights and total DFFT, protein, DNA, fat, and ash amount of all nursed mammary glands of each sow were increased as litter size increased (P<.05). Changing litter size from 6 to 12 pigs resulted in 2,098, 432, 253, 227, 4.4, 178, and 20 g increases in the amounts of total mammary wet weight, dry weight, DFFT, protein, DNA, fat, and ash, respectively, on d 21 of lactation. Litter weight gain was 18.1 kg greater in sows with 12 pigs than in sows with 6 pigs. Sows with a larger litter size had a greater increase in total mass of mammary gland tissue and litter weight but had lower growth of individual nursed mammary glands and individual pigs than sows with the smaller litter size. The need for nutrients to support additional mammary gland and litter growth as litter size increases should be considered when estimating nutrient requirements for lactating sows. Sows need an additional .96 g lysine per day to account for mammary gland growth for each pig added to a litter.
选用28头初产母猪来确定产仔数对泌乳期乳腺和哺乳仔猪生长的影响。通过产后立即交叉寄养，将产仔数设定为6、7、8、9、10、11或12头仔猪。每个产仔数组分配4头母猪。泌乳期母猪每日允许摄入的最大代谢能为13.6兆卡，赖氨酸为46.3克。在泌乳第21天（20.6±1.1）屠宰母猪。屠宰时采集乳腺，去除皮肤和多余的脂肪垫。将每个腺体分离、称重并研磨进行化学分析。测定干物质、无脂干组织（DFFT）、粗蛋白、灰分和DNA含量。数据集中仅包括已知有仔猪哺乳的腺体。随着产仔数增加，单个有仔猪哺乳的乳腺的湿重、干重以及DFFT、蛋白质、DNA、灰分和脂肪含量呈线性下降（P<0.05）。在泌乳第21天，产仔数对DFFT、蛋白质和DNA的百分比有二次效应（P<0.05）。随着产仔数增加，每头母猪所有有仔猪哺乳的乳腺的总湿重、干重以及总DFFT、蛋白质、DNA、脂肪和灰分含量均增加（P<0.05）。在泌乳第21天，将产仔数从6头增加到12头，乳腺总湿重、干重、DFFT、蛋白质、DNA、脂肪和灰分含量分别增加2098、432、253、227、4.4、178和20克。产12头仔猪的母猪的仔猪增重比产6头仔猪的母猪高18.1千克。与产仔数少的母猪相比，产仔数多的母猪乳腺组织总质量和仔猪体重增加更多，但单个有仔猪哺乳的乳腺和单个仔猪的生长较慢。在估算泌乳母猪的营养需求时，应考虑随着产仔数增加支持额外乳腺和仔猪生长所需的营养。每增加一头仔猪，母猪每天需要额外摄入0.96克赖氨酸以满足乳腺生长。
