PSXIV-27 Use of narasin in diets for lactating ewes

• Published in: Journal of animal science Vol. 97; no. Supplement_3; p. 448
• Main Authors: Assis, Rhaissa Garcia de, Biava, Janaina S, Eckermann, Nathalia R, Sturion, Thamires U, Souza, Terezinha T de, Cerutti, Maria Fernanda, Paula, Matheus F F V de, Polizel, Daniel M, Pires, Alexandre Vaz, Ferreira, Evandro M
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 05.12.2019
• Subjects: POSTER PRESENTATIONS; milk production; ionophore; lactation; milk composition; ewes
• ISSN: 0021-8812; 1525-3163
• DOI: 10.1093/jas/skz258.882

Abstract The objective of this study was to define the ideal level of narasin to be used in diets for lactating ewes. Forty Dorper vs. Santa Inês ewes (53.6 ± 9.6 kg BW and 14 d in milk) were penned individually and used in a complete randomized block design. Ewes were fed a basal diet (16.77 ± 0.35% CP) containing 50% concentrate and 50% coastcross hay. The treatments were: 0N - control diet; 13N - 13 mg of narasin/kg of DM; 20N - 20 mg of narasin/kg of DM; 27N - 27 mg of narasin/kg of DM. Ewes were fed the diets from the wk 2 to 10 of lactation. Milk production was determined every 7 d during the experiment. Ewes were separated from lambs and mechanically milked for emptying of the mammary gland. After 3 hours, using the same procedure, milk production was recorded and samples collected for milk composition analysis. For DMI, there was a quadratic effect of treatments (0N=2.417; 13N=2.491; 20N=2.334; 27N=2.078 kg/d; P = 0.02). The milk production (g/3h) presented a quadratic response to levels of narasin (0N=186.37; 13N=194.91; 20N=194.01; 27N=164.49 g/3h; P = 0.03). In the milk composition, there was a linear reduction in the content of protein (0N=5.31; 13N=5.13; 20N=4.94; 27N=5.00%; P = 0.01) and ESD (0N=11.22; 13N=11.15; 20N=10.84; 27N=10.98 %; P = 0.03). However, the contents of fat, lactose and total solids were not affected by the treatments. As a consequence, the productions (g/3 hours) of fat, lactose and total solids were not affected by the diets. A quadratic response was observed for the productions (g/3 h) of protein (0N=9.86; 13N=9.76; 20N=9.52; 27N=8.29; P = 0.04) and ESD (0N=20.73; 13N=21.45; 20N=21.18; 27N=18.28; P = 0.03). In conclusion, 13 mg/kg of DM is the best concentration of narasin to be used in diets for ewes, values higher than this can compromise milk production and composition.