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Increasing dietary energy supply makes replacement gilts grow quickly to meet the breeding standard as soon as possible, but it often leads to mammary gland fat deposition and dysplasia, affecting milk production. Providing high fiber diets during puberty has been shown to decrease gilts’ mammary gland development before lactation, although this strategy also increased their lactation performance. Therefore, the hypothesis of the present study was that supplementation of fiber in high-energy diets could improve mammary gland development in gilts. To study the effects of energy and dietary fiber on mammary development in gilts and its possible mechanisms, 32 gilts (Landrace × Yorkshire) were randomly allocated into a 2 × 2 factorial design to receive a diet with low or high energy [low energy: 33.37 MJ/d digestible energy; high energy: 41.87 MJ/d digestible energy] and low or high fiber (low fiber: 0.3 kg/d dietary fiber, high fiber: 0.6 kg/d dietary fiber). The weight of mammary tissue was recorded. The mammary glands were collected for further analysis.
The high energy intake increased the relative weight of mammary tissue and the content of mammary fat. At the same time, the oil red staining of mammary slices also showed an increase in mammary fat content in the high-energy treatment. High energy intake increased the DNA concentration in mammary tissues. In addition, high energy intake increased the concentration of triglycerides, free fatty acids, and total cholesterol in the blood of gilts, and the supplementation of high fiber tended to reduce free fatty acids, total cholesterol, and estradiol. Proteomic analysis suggested that there were notable differences in the cytoskeleton, intracellular non-membrane-bounded organelle, apoptosis, receptor activity, and endopeptidase inhibitor activity in molecular function between the energy and fiber effects. High fiber intake also decreased the mRNA expression of 5-HT7, Bax, and caspase-3 in the mammary tissue of gilts, which further confirmed the importance of fiber in regulating mammary development in gilt.
The results of the present work indicate that increasing gilt energy intake improved mammary weight and fat deposition and increased mammary cell apoptosis. Increased fiber intake reduced mammary fat deposition and mammary cell apoptosis at high energy intake in gilts.
Xu S, Tang L, Xu H, Yang Y, Cao M, Chen S, Jiang X, Li J, Lin Y, Che L, Fang Z, Feng B, Zhuo Y, Wang J, Wu D. Effects of Energy and Dietary Fiber on the Breast Development in Gilt. Frontiers in Veterinary Science. 2022; 9. https://doi.org/10.3389/fvets.2022.830392