Milk production responses to feeding fatty acids

Abstract

Two trials were conducted to determine the milk production response to feeding a highly saturated free fatty acid supplement to grazed dairy cows in early lactation. The trials were conducted during spring and autumn, respectively. Sixty-five Friesian cows were supplemented with fat-prills at rates of 0,00 (control), 0,25 and 0,50 kg/d during the first 60 days of lactation, in addition to the usual concentrates fed at levels equivalent to 2% of body-weight in early lactation. Cows in their first lactation did not respond to the fatty-acid supplements. The response of multiparous cows is described by the equation: peak yield (FCM) = 22,44 + 5,88 (kg fat suppl/d) + 3,52 (body-weight loss/d) (n = 40; R = 0,57; P < 0,01), for the combined trial data. No significant differences were recorded for the butterfat and protein concentrations in the milk. A tendency towards increased weight losses, although non-significant, was recorded for each additional increment of fatty-acid supplement over that of the control cows.

Twee proewe is onderskeidelik in die lente en herfs uitgevoer om die melkproduksierespons te bepaal wanneer 'n hoogsversadigde vryevetsuuraanvulling aan weidende melkbeeste in vroeë laktasie gevoer word. Vyf-en-sestig Frieskoeie is benewens kragvoer (gevoer teen 2% van liggaamsmassa gedurende vroeë laktasie) vir die eerste 60 dae van laktasie ook aangevul met die volgende peile 'fat-prills' bo-op die kragvoer: 0,00 (kontrole), 0,25 en 0,50 kg/dag. Koeie in hul eerste laktasie het nie 'n respons getoon op die vetsuuraanvulling nie. Die ouer koeie se respons word deur die volgende vergelyking voorgestel: piekproduksie (VGM) = 22,44 + 5,88 (kg vetaanvulling/ dag) + 3,52 (liggaamsmassaverlies/dag) (n = 40; R = 0,57; P < 0,01), vir die gekombineerde proefdata. Geen betekenisvolle verskille kon tussen bottervet- en proteïenkonsentrasies in die melk gevind word nie. 'n Neiging tot verhoogde massaverlies, alhoewel nie betekenisvol nie, is vir elke addisionele verhoging van vetsuuraanvulling bo dié van die kontrolekoeie gevind.

Keywords: Dairy cows, free fatty acids, milk production.