Production Responses of Dairy Cows to Dietary Supplementation with Conjugated Linoleic Acid (CLA) During the Transition Period and Early Lactation

Abstract

Holstein cows (n = 30) entering second or greater lactation were fed fat supplements (90 g/d of fatty acids) consisting of Ca salts of either palm fatty acid distillate (control) or a mixture of palm fatty acid distillate and mixed isomers of conjugated linoleic acid (CLA, 30.4 g/ d) from 2 wk prepartum through 20 wk postpartum to determine whether CLA would inhibit milk fat synthesis during early lactation and, in turn, affect energy metabolism of dairy cows during the transition period and early lactation. Feeding CLA did not affect DMI or plasma concentrations of glucose, nonesterfied fatty acids, or beta-hydroxbutyrate during the prepartum period and did not affect postpartum DMI. Feeding CLA reduced milk fat content by 12.5% during early lactation; however, cows fed CLA tended to produce approximately 3 kg/d more milk during the first 20 wk of lactation. Feeding CLA tended to decrease the contribution of short- and medium-chain (C < or = 16) fatty acids to milk fat. Changes in milk yield, milk fat content, and milk fatty acid composition were not apparent until after the second week of lactation. Yield of 3.5% fat-corrected milk, milk protein content, milk protein composition, and calculated energy balance were not affected by treatment. Postpartum concentrations of glucose, nonesterfied fatty acids, and beta-hydroxbutyrate in plasma and hepatic content of glycogen and triglycerides were similar between treatments. These data imply that with CLA treatment in early lactation, dairy cows decreased milk fat synthesis and appeared to respond by partitioning more nutrients toward milk synthesis rather than improving net energy balance.

Recent advances in the regulation of milk fat synthesis

“…In addition, CLAinduced MFD did not alter plasma NEFA response to an epinephrine challenge or plasma glucose response to an insulin challenge; thus, homeostatic responses associated with the regulation of lipolysis and glucose uptake were unaltered (Baumgard et al, 2002a;de Veth et al, 2006). Hepatic triglyceride concentration was also unaffected during CLA-induced MFD (Bernal-Santos et al, 2003;Castañ edaGutiérrez et al, 2005). The mechanism of CLA is also independent of the stage of lactation as trans-10, cis-12 CLA reduces milk fat yield during all phases of the lactation cycle (Perfield et al, 2002;Bernal-Santos et al, 2003;Castañ edaGutiérrez et al, 2005), although a larger dose is required in early lactation (Moore et al, 2004;Odens et al, 2007).…”

“…Hepatic triglyceride concentration was also unaffected during CLA-induced MFD (Bernal-Santos et al, 2003;Castañ edaGutiérrez et al, 2005). The mechanism of CLA is also independent of the stage of lactation as trans-10, cis-12 CLA reduces milk fat yield during all phases of the lactation cycle (Perfield et al, 2002;Bernal-Santos et al, 2003;Castañ edaGutiérrez et al, 2005), although a larger dose is required in early lactation (Moore et al, 2004;Odens et al, 2007).…”

“…First, MFD is a specific reduction in milk fat yield with no change in the yields of milk or milk protein; this phenotype is sustainable for long periods as shown by studies involving CLA-induced MFD (Perfield et al, 2002;Bernal-Santos et al, 2003;Castañ edaGutié rrez et al, 2007). In addition, milk fat synthesis is rescued after termination of CLA treatment, with the time course for recovery being similar to the progressive pattern of decline (Baumgard et al, 2000).…”

Role of trans fatty acids in the nutritional regulation of mammary lipogenesis in ruminants

“…However, infusion of trans-10, cis-12 CLA/day in higher amounts (7.0 to 14.0 g/day) causes a disproportionately larger reduction in the secretion of fatty acids synthesized de novo, effects that are also accompanied by significant decreases in milk fat SCD desaturase indices. Observations from several studies indicate that anti-lipogenic potential of trans-10, cis-12 CLA supplied as calcium salts of a mixture of CLA isomers in the diet is lower immediately in cows post partum compared with established lactation (Bernal-Santos et al, 2003;Gervais et al, 2005). Lowered inhibition of mammary lipogenesis does not appear to be related to variations in mammary supply and incorporation of trans-10, cis-12 CLA in milk fat (Bernal-Santos et al, 2003;; or due to specific changes in plasma glucose, insulin, leptin or NEFA concentrations Kay et al, 2006).…”

“…Observations from several studies indicate that anti-lipogenic potential of trans-10, cis-12 CLA supplied as calcium salts of a mixture of CLA isomers in the diet is lower immediately in cows post partum compared with established lactation (Bernal-Santos et al, 2003;Gervais et al, 2005). Lowered inhibition of mammary lipogenesis does not appear to be related to variations in mammary supply and incorporation of trans-10, cis-12 CLA in milk fat (Bernal-Santos et al, 2003;; or due to specific changes in plasma glucose, insulin, leptin or NEFA concentrations Kay et al, 2006). It has been suggested that the coordinated reduction in the expression of genes encoding for key lipogenic enzymes in mammary tissue as a direct response to trans-10, cis-12 CLA may be prevented due to the attenuation of cellular signalling systems at the onset of lactation (BernalSantos et al, 2003;.…”