Abstract #T255

# T255
Comparison between dietary palmitic and palmitoleic acid effects on milk performance and gene expression of granulosa cells in early lactation cows.
Marguerite Plante-Dube*1, Isabelle Gilbert1, Rachel Gervais2, Claude Robert1, Bruno Vlaeminck3, Veerle Fievez3, Paul Y. Chouinard1, 1Institute of Nutrition and Functional Foods, Laval University, Quebec, QC, Canada, 2Department of Animal Sciences, Laval University, Quebec, QC, Canada, 3Department of Animal Production, Ghent University, Ghent, East Flanders, Belgium.

In early lactation, high-yielding cows suffer from negative energy balance associated with an increase in nonesterified fatty acid (FA) concentrations in plasma and follicular fluid. Consequently, folliculogenesis and granulosa cell metabolism can be impaired, but the effects may depend on FA composition. We hypothesized that, in dairy cows, milk production, milk fat concentration, and expression of genes related to lipid and energy metabolism of the granulosa cells are affected differently by palmitic and palmitoleic acids. Twenty Holstein multiparous cows in late gestation were randomly assigned to 200 g/d of FA supplements enriched in i) palmitic acid (PA; Palmit 80; Natu’oil Services Inc.; >80% 16:0) in the rumen or ii) palmitoleic acid (POA; Sea buckthorn oil; New Directions Aromatics Inc.; 28% c9–16:1, 27% 16:0, and 22% c9–18:1) in the abomasum. The treatment period ranged from 19 ± 8 d before calving to 67 ± 4 d postcalving. On wk 2, 6, and 10 following parturition, milk yield was recorded and milk samples collected during 3 consecutive days and composited. Ovum pick up (OPU) sessions were carried out at 46 and 67 ± 3 d postcalving. At each OPU session, cumulus oocyte complexes and granulosa cells were recovered. Total RNA was extracted from granulosa cells and the response of gene expression associated with lipid metabolism was analyzed by RT-qPCR. A repeated measures analysis was conducted using the MIXED procedure of SAS to test the effects of treatment, days in milk and their interaction. Treatments did not affect milk yield (39.6 ± 2.2 kg/d; P = 0.74) or fat concentration (3.88 ± 0.14%; P = 0.27). Abundances of mRNA for stearoyl-CoA desaturase (SCD1, SCD5) and perilipin 2 in granulosa cells were not different between treatments (P > 0.12). Compared with PA, POA tended to decrease the expression of gene encoding for insulin receptor (P = 0.08). Also, SCD5 mRNA abundance was increased from first to second OPU (P = 0.05) and a similar tendency was observed for perilipin 2 (P = 0.07). These results suggest that stage of lactation and dietary FA profile may affect metabolism of granulosa cells in early lactation cow.

Key Words: dairy cow, fat supplement, gene expression