Effect of feeding Camelina sativa cake on rumen microbiota and gene expression in follicular cells in dairy Italian Holstein Friesian heifers

Omega-3 PUFAs have unique role in several biological systems in mammals. However, its impact on rumen microbial environment could represent a critical point for both rumen welfare and its availability for the animal. The aim of the study was to evaluate the effects of the inclusion in the diet of a terrestrial vegetable and sustainable source of omega-3 PUFAs (Camelina sativa cake) in dairy heifers on rumen microbiota and gene expression of fertility markers in follicular cells. The trial was conducted at the tie stall dairy barn of the Experimental Farm of Animal Production Research and Teaching Centre of Lodi, University of Milan, Italy and lasted 56 d. Sixteen Italian Holstein Friesian heifers 12 mo old were divided in 2 homogeneous groups randomly allocated to 2 treatments: CAME (n = 8) receiving the basal diet supplemented with 800 g/head/ day of camelina cake and CTR (n = 8) receiving the basal diet supplemented with an isonitrogenous and isoenergetic soybean-based premix. Basal diet consisted of a dry TMR composed by alfalfa hay, durum wheat middlings, sugar cane molasses, corn meal, soybean hulls, rice bran, sunflower meal and minerals (15.15 PG, 42.63 NDF, 19.43 starch on DM basis). Performances were recorded weekly, feed intake daily. Rumen and follicular content samples were collected at d 0, 28 and 56 of the trial. Follicular developmental competence was assessed by RT-PCR analysis. Performance data were analyzed by PROC MIXED of SAS for repeated measures. No differences were detected for live BW, FCR and BCS, but an interaction between diet and time was observed (P ≤ 0.05) on DMI with higher values for CAME at d 34, 51, 52 and 55 compared with CTR (14.44 ± 0.93 kg vs. 10.47 ± 0.93 kg; 13.36 ± 0.93 kg vs. 10.81 ± 0.93 kg; 13.21 ± 0.93 kg vs. 10.86 ± 0.93 kg; 13.99 ± 0.93 kg vs. 11.15 ± 0.93 kg). Higher expression levels for HAS2, GREM1, LHCGR and FSHR genes were detected in CAME group compared with CTR, suggesting a positive effect of treatment diet. Rumen microbiota was influenced by dietary treatment both at 28 and 56 d showing significant α diversity values.