Effects of feeding high-linoleate safflower seeds on postpartum reproduction in beef cows1,2

Abstract

Two experiments were conducted to evaluate reproductive responses to supplemental high-linoleate safflower seeds in postpartum beef cows. In Exp. 1, 18 primiparous, crossbred beef cows (411 +/- 24.3 kg of BW) were fed Foxtail millet hay starting 1 d postpartum at 1.68% of BW (DM basis) and a low-fat control (control: 63.7% cracked corn, 33.4% safflower seed meal, and 2.9% liquid molasses; DM basis) at 0.35% of BW (n = 9) or a supplement (linoleate) containing 95.3% cracked high-linoleate (79% 18:2n-6) safflower seeds and 4.7% liquid molasses (DM basis) at 0.23% of BW (n = 9). Beginning 1 d postpartum, blood was collected every 3 d for sera. Cows were slaughtered at 37 +/- 3 d postpartum for collection of hypothalami, anterior pituitary glands, liver, ovarian follicles, and uterine tissue. By 37 +/- 3 d postpartum, dietary treatment did not influence ovarian follicular development (P >or= 0.17), hypophyseal concentrations of LH (P = 0.14), or concentrations of IGF-I in liver (P = 0.15). In contrast, anterior pituitary glands from linoleate cows contained more FSH (P = 0.02) than control cows and linoleate cows had less IGF-I in the medial basal hypothalamus (P = 0.05), preoptic area (P = 0.06), and in follicular fluid (P <or= 0.03) from follicles less than 15 mm in diameter. In Exp. 2, twenty-four 3-yr-old multiparous beef cows (initial BW 473.9 +/- 9.2 kg) were fed chopped bromegrass hay at 2.1% of initial BW starting 1 d postpartum and a low-fat supplement (control) fed at 0.6% of initial BW or a high-linoleate supplement (linoleate) fed at 0.4% of initial BW until 80 d postpartum. Cows were observed for estrus twice daily from d 30 to 80 postpartum and treated with GnRH between 40 and 45 d postpartum. Seven days after GnRH administration cows were given PGF(2alpha) and were checked for estrus and artificially inseminated until 80 d postpartum. The magnitude of GnRH-induced release of LH (P = 0.82) or FSH (P = 0.86) did not differ between treatments. However, peak serum concentrations of estradiol during proestrus after treatment with PGF(2alpha) were less (P = 0.04) in linoleate than control cows. In conclusion, fat supplementation with high-linoleate safflower seeds did not improve the development of ovarian follicles and detrimentally affected early postpartum fertility possibly because of a reduction in IGF-I concentrations in tissues essential to reproduction.

Optimising reproductive performance of beef cows and replacement heifers

“…While many studies have examined the effects of various fatty acid-based supplements on aspects of the reproductive process in dairy cows, there have been few reports for beef cows. Scholljegerdes et al (2009) recorded lower tissue concentrations of LH and IGF-1, follicle numbers, systemic oestradiol and overall conception rate in beef cows supplemented with high-linoleate safflower seeds compared with unsupplemented controls. SimiIarly, Martin et al (2010) observed no advantage of supplementing heifers with soya beans in either productive or reproductive efficiency.…”

Effects of short-term oilseed supplementation on reproductive performance in beef heifers

“…In a previous report, pregnancy rates to TAI or natural service were not influenced by feeding flaxseed or sunflower seeds starting 25 d prior to synchronization with CIDRs and continuing for 50 d (Colazo et al 2004). Furthermore, responses due to supplementation of lipid high in C18:2n-6 has been equivocal with some reporting increased (Whitney et al 2000;Cerri et al 2009;Juchem et al 2010), no difference (Funston et al 2002;Banta et al 2008), or decreased (Alexander et al 2002Ambrose et al 2006;Scholljegerdes et al 2009) reproductive success. This discrepancy in reported responses is likely due to variation in the amount of fatty acid actually reaching specific tissues.…”

Body condition score and day of lactation regulate fatty acid metabolism in milk somatic cells and adipose tissue of beef cows

“…Thus, repression of adipose tissue lipoprotein lipase (LPL) and acetyl-CoA carboxylase (ACC) genes (Travers et al, 1997), with simultaneous up-regulation of the hormone sensitive lipase (HSL) gene (Martin-Hidalgo et al, 1994) would provide the mammary gland with endogenous energy supplies to meet the metabolic demands of lactation. Our laboratory has examined the effects of dietary supplemental fat on body condition score (BCS; 1 = emaciated and 9 = obese; Wagner et al, 1988) and energy partitioning during early lactation in beef cows (Bottger et al, 2002;Lake et al, 2005Lake et al, , 2006aScholljegerdes et al, 2009). Generally, dietary oil supplementation affected tissue fatty acid profile, but effects on biochemical events were not always evident.…”