Effect of pre-slaughter transport stress on carcass weight, rumen fermentation and bacterial community of growing goats

Abstract This study evaluated the effects of pre-slaughter transport stress on the rumen fermentation and bacterial community of growing meat goats. Fifty-four male Spanish growing meat goats (28.9 ± 4.5) were stratified by body weight and randomly assigned into three treatment groups (n = 18 per treatment; 1) No transport stress (CON), 2) Transport stress for 30 mins (LS), and 3) Transport stress for 3 h (HS). Blood samples were collected before and after transport to estimate plasma cortisol concentrations. At the end of the experiment, the goats were slaughtered to determine the carcass weight and to collect rumen ruminal content for pH, 16 sRNA gene sequencing, and volatile fatty acid profile. The Linear discriminant analysis (LDA) effect size and the functional profiling software (PICRUst) were used to estimate the differentially abundant taxa and predicted the functional potential of the microbial community, respectively. Compared to CON, both LS and HS increased (P < 0.01) plasma cortisol concentrations (27.5 vs. 130.1 and 117.7 ng/ mL), no differences were observed in hot carcass weight and VFA profile (P > 0.05). Rumen pH was lower (P < 0.05) in HS compared to CON or LS (6.44 vs 6.75 or 6.77). Compared to CON, LS reduced the relative abundance of Ruminococcaceae UCG 014 (LDA = 4.20; P = 0.01), whereas no effect was observed for HS. Compared to CON, predicted microbial functions associated with the immune system, translation, and enzyme activities were downregulated by LS while that of energy metabolism was downregulated by HS. Compared to HS, the predicted microbial functions associated with immune and digestive systems were downregulated by LS. This study demonstrated that LS transport stress has a more pronounced effect than long-term exposure on the rumen bacterial community and predicted functional potential in growing meat goats.