A Supplement Containing Trans-10, Cis-12 Conjugated Linoleic Acid Reduces Milk Fat Yield but Does Not Alter Organ Weight or Body Fat Deposition in Lactating Ewes1–3

Abstract

Conjugated linoleic acids (CLA) have been demonstrated to be a potent inhibitor of milk fat synthesis in ruminants, but effects on carcass composition and organ weight are unknown. Our objectives in this experiment were to determine the dose response of ruminally protected CLA on the performance, organ weight, and fatty acid (FA) composition of early lactation dairy ewes. Twenty-four multiparous dairy ewes were fed a basal diet for 10 wk that was supplemented with a lipid-encapsulated CLA at 1 of 3 levels: no CLA (control, CON), low CLA (L-CLA), or high CLA (H-CLA) to supply 0, 1.5, or 3.8 g/d, respectively, of both trans-10, cis-12 and cis-9, trans-11 CLA. Dry matter intake was not affected (P > 0.05) by dietary treatment. Ewes fed H-CLA had a 13% higher milk yield compared with those receiving either CON or L-CLA. Compared with CON, milk fat yield (g/d) was 14 and 24% lower in ewes fed L-CLA or H-CLA, respectively. Supplementing ewes with CLA did not affect carcass or organ weights, carcass composition, or organ FA content. Compared with ewes receiving the CON diet, CLA supplementation had little effect on the FA composition of the Longissimus dorsi, although cis-9, trans-11 and trans-10, cis-12 CLA were increased in ewes receiving H-CLA. The current findings are consistent with the view that the energy spared by the CLA reduction in milk fat content was mainly partitioned to milk yield and there was no evidence of organ hypertrophy or liver steatosis.

Short communication: Effect of conjugated linoleic acid on concentrations of fat-soluble vitamins in milk of lactating ewes

“…The magnitude of this effect was comparable with that reported from others. For example, when 2.4 to 6.1 g of trans-10,cis-12-CLA per 100 kg of BW and day were fed to ewes, the reported reductions in milk fat percentage were between 15 and 34% (Lock et al, 2006;Sinclair et al, 2010). In the present study, the composition of milk FA was altered as well.…”

“…Although we could not measure milk yield in the present study, milk yield is generally unaffected by CLA feeding (Bauman et al, 2008;Hussein et al, 2013) or sometimes increased by about 10% (Lock et al, 2006;Sinclair et al, 2010). This makes it probable that not only milk vitamin concentrations, but also the milk vitamin output, were maintained or increased in the present study.…”

Improvement of Milk Composition and Properties of Labneh Using Oil Seeds as Supplement for Lactating Zaraibi Goat Rations

“…Because of the transient nature of RA formed in the rumen, endogenous synthesis from VA through mammary Δ9-desaturase is considered the principal origin of this CLA isomer in ruminant milk (Shingfield et al, 2008). Probably because the usually high ruminal BH of linoleic acid can be further increased with marine lipid supplements (up to 90% according to Sinclair et al, 2010). The notable rise in milk trans-C18:1 would also support this hypothesis.…”

Biosynthesis of milk fat, protein, and lactose: roles of transcriptional and posttranscriptional regulation

“…The existence of a link between CLA and milk fat depression was demonstrated more than 10 yr ago by the abosamal infusion of a supraphysiological dose of t10,c12-CLA (17) and has been confirmed multiple times in bovine (reviewed in Ref. 16) and other species, including sheep (101,129,207), goat (9, 73, 79, 80), mouse (91,110), and rat (92,184).…”