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Effect of dietary supplementation of polyunsaturated fatty acids on intake, digestibility, milk production, and milk fatty acids of dairy sheep: A meta-analysis.

A. A. Pech-Cervantes

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06-24-2020

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Abstract:

W75
Effect of dietary supplementation of polyunsaturated fatty acids on intake, digestibility, milk production, and milk fatty acids of dairy sheep: A meta-analysis.
A. A. Pech-Cervantes*1, I. M. Ogunade2, C. A. Sandoval-Castro3, Z. M. Estrada-Reyes1, A. Oliveira4, D. Vyas5, A. T. Adesogan5. 1Agricultural Research Station, Fort Valley State University Fort Valley, GA, 2College of Agriculture, Communities, and the Enviroment, Kentucky State University Frankfort, KY, 3Faculty of Veterinary Medicine and Animal Science, Autonomous University of Yucatan Merida, Yucatan, Mexico, 4Institute of Agriculture and Enviromental Sciences, Federal University of Mato Grosso Mato Grosso, Sinop, Brazil, 5Department of Animal Sciences, University of Florida Gainesville, FL.

We conducted a meta-analysis to examine the effects of dietary supplementation of polyunsaturated fatty acids (PUFA) on intake, digestibility, milk production, and milk fatty acids of lactating dairy. A systematic search in the literature from 1990 to 2019 was conducted and data from 33 peer-reviewed papers with 58 treatments and 1,350 sheep were used to evaluate the magnitude of the effect (effect size) using raw mean differences (RMD) between PUFA supplementation and control. The means were weighted by inverse variance in a mixed model and heterogeneity was calculated by meta-regression and subset analysis using forage (hay, silage, grass), breed (sarda, assaf, crossbreed and others), source (oils, byproducts, mixtures), and level of supplementation as covariates. Dietary levels of PUFA were from 40.1 to 101.5 g/d. Compared with control, PUFA did not affect (P > 0.05) DMI (RMD = 0.01 kg/d [−0.01, 0.06]), milk yield (RMD = 0.02 kg/d [−0.06, 0.02]) and milk fat concentration (RMD = −0.08% [−0.22, 0.05]); however, PUFA increased (P < 0.05) C18:2 and C18:3 concentrations in milk (RMD = 0.12 g/100 g fatty acid methyl esters (FAME) [−0.1, 0.26], and 0.13 g/100 g FAME [0.06, 0.17]), dry matter digestibility (RMD = 2.2% [1.31, 3.1]), lactose concentration (RMD = 0.08% [0.03, 0.14]), and milk trans-10,cis-12 CLA (0.03 g/100 g FAME [0.03, 0.04]). In fact, concentrations of total PUFA in milk were increased by 23.9% (RMD = 1.41 g/100 g FAME [1.16, 1.65]), whereas total saturated fat in milk was decreased by 7.6% (RMD = −5.3 g/100 g FAME [−6.6, −3.96]).The subset analysis showed that oils supplementation increased C18:2 in milk (0.31 vs 0.03; −0.12 g/100 FAME; P < 0.05), whereas byproducts as a source of PUFA were more effective at increasing C18:3 in milk (0.24 vs 0.12, 0.02 g/100 FAME; P < 0.05). Despite the high heterogeneity (I > 95%) observed in this study, PUFA supplementation increased milk quality (increased concentration of unsaturated fatty acids and lactose), but had no effects on the performance of lactating dairy sheep.

Keywords: dairy sheep, fatty acids, meta-analysis.