Effects of Varying Doses of Supplemental Conjugated Linoleic Acid on Production and Energetic Variables During the Transition Period

Abstract

Supplementing a high dose of dietary conjugated linoleic acid (CLA) inhibits milk fat synthesis in dairy cows immediately postpartum. During negative net energy balance (EBAL), it appears that moderate CLA-induced milk fat depression causes a positive response in milk yield; however, as milk fat depression becomes more severe, the milk yield response diminishes. Multiparous Holstein cows (n = 31) were randomly assigned to 1 of 3 treatments beginning 9 +/- 6 d before expected calving and ceased at 40 d in milk (DIM): 1) 578 g/d of a rumen-inert (RI) palm fatty acid distillate (control), 2) 600 g/d of RI-CLA for the entire trial period (CLA-1), and 3) 600 g/d of RI-CLA until 10 DIM followed by 200 g/d for the remainder of the trial (CLA-2). Each dose provided equal amounts of fatty acids by replacing and balancing each treatment with a RI palm fatty acid distillate. Doses provided a total of 522 g of fatty acids/ d and 0, 174, or 58 (depending upon DIM) g of CLA (mixed isomers)/d. To improve palatability, doses were mixed with 600 g/d of dried molasses; one-half of the supplement was fed at 0800 h, and the remainder at 1900 h. Individual milk yield, dry matter intake, and body weight were recorded daily and milk composition determined every other day. There was no overall CLA effect on either the content or yield of milk protein or lactose. Both CLA treatments decreased overall milk fat content (26.0 and 18.3%) and yield (22.5 and 17.3%) with CLA-induced milk fat depression becoming significant by d 8. The CLA-induced milk fat depression increased in magnitude with progressing DIM until reaching a plateau on d 18 for CLA-1 (43%) and on d 14 for CLA-2 (33%), although neither milk fat trans-10, cis-12 CLA content (1.8 mg/g) nor its transfer efficiency (6.3%) changed over time. Treatments had no effect on overall dry matter intake or milk yield, but there was a treatment x time interaction for milk production, as cows fed either CLA treatment had increased milk yield after the second week of lactation. Cows fed either CLA treatment had a significant improvement in overall EBAL (-5.1 vs. -1.8 Mcal/d), a decrease in nonesterified fatty acid levels (12%), and an increase in glucose levels (11%). A dietary supplement containing trans-10, cis-12 CLA markedly improves EBAL and bioenergetic variables and increases milk yield in the total mixed ration-fed transitioning dairy cow.

Production performance and pattern of milk fat depression of high-yielding dairy cows supplemented with encapsulated conjugated linoleic acid

“…This is in contrast to protein, in which the E-CLA cows consumed 120 g/day less protein than the controls with no concurrent reduction in protein yield in milk. However, in Odens et al (2007), no reduction in DMI and a significant improvement in EB were observed for cows fed CLA from 9 6 6 days pre-calving until 40 days post-calving.…”

“…In several studies in which cows were fed a variety of CLA supplements in early or mid-lactation, no effect on DMI was observed (Piperova et al, 2004;Castañ eda-Gutié rrez et al, 2005;Castañ eda-Gutié rrez et al, 2007;Odens et al, 2007). However, a trend for lower intake was observed in cows fed calcium salts of CLA in early lactation (Selberg et al, 2004) or abomasally infused with CLA supplements (Baumgard et al, 2000).…”

Transcriptional regulation of acetyl-CoA carboxylase α isoforms in dairy ewes during conjugated linoleic acid induced milk fat depression

“…The difference in response of the ACC-α transcripts in the mammary gland to CLA during the different stages of lactation might be explained by the magnitude of MFD or source of milk FA. Previous work in cows has demonstrated that higher doses of trans-10, cis-12 CLA are required to induce MFD during early lactation compared with mid and late lactation (CastanedaGutierrez et al, 2005;Odens et al, 2007). This may be due to transcript-specific regulation of ACC-α.…”

Recent advances in the regulation of milk fat synthesis

“…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).…”

“…Under certain marketing systems and management schemes, it may be advantageous to reduce milk fat yield , and in some feeding and management systems the reduction in milk fat yield has allowed for a repartitioning of nutrients to support increased milk and milk protein yield (e.g. Bernal-Santos et al, 2003;Mackle et al, 2003;Lock et al, 2006b;Odens et al, 2007). Producers may also find it advantageous to induce MFD during periods of limited feedstuff availability such as inadequate rainfall in pasture-based systems or for a short period while breeding.…”