Effect of feed restriction on gene expression of bacterial enzymes produced in the rumen of Morada Nova lambs of different sex classes

Animal husbandry in tropical or arid environments is a challenge to farmers, mainly due to the quality and quantity of food available during prolonged periods of drought. To observe the effects of scarcity on gene expression of enzymes from fibrolytic, amylolytic, proteolytic and methanogenic microorganisms in the ruminal contents of Morada Nova lambs, belonging to different sex class (intact males, castrated males and females). The experiment was done in completely randomized design arranged in a 3 × 3 factorial scheme, with twenty-seven lambs of approximately 120 days of age and14.5 ± 0.89 kg average initial body weight. The diet was formulated in a proportion of roughage:concentrate 60:40, based on Tifton-85 (Cynodon sp.) hay, ground corn and soybean meal. The ruminal contents of the animals were collected post-slaughter and used for determining gene expression of ruminal enzymes by qPCR. Among the primers tested, the target genes β-D-xylosidase/α-L-arabinofuranosidase (xylbf), xylanase (xlpr), amylase (amy) and methyl coenzyme M reductase α (mcrA) were amplified in qPCR. There was no interaction between sex class and feed restriction levels or sex class effect on the gene expression of microbial enzymes. The genes xylbf and xlpr were less expressed in animals subjected to restrictive eating, reducing the activity of hemicellulolytic bacteria.