Effect of sunflower seed husk and rape straw in total mixed ration during peri-puberty on testis development in Hu lambs

Sunflower seed husk (SH) and rape straw (RS) are widely used in mutton sheep husbandry in the Hexi Corridor of China. This study explored whether or not a pre-puberty lamb diet consisting of sunflower SH and RS affects ram testis development. Fifty 60-day-old healthy Hu ram lambs (average body weight of 22.3 ± 0.1 kg) were randomly divided into two groups. In each treatment group, 25 lambs were allocated to five pens (five lambs per pen). The SH group received a diet containing 20 % SH, and the RS group received a diet containing 20 % RS. After a 77-day feeding trial, three lambs, except for the heaviest and lightest in each pen, were humanely slaughtered and investigated. Results revealed that the two groups had no difference in body weight (39.23 ± 0.52 kg vs. 38.53 ± 0.46 kg, P = 0.321). However, the testis weight (288.74 ± 23.45 g vs. 215.18 ± 17.96 g), volume (294.29 ± 25.39 mL vs. 208.67 ± 16.63 mL), epididymis weight (38.38 ± 1.44 g vs. 33.86 ± 1.37 g), testicular index (0.74 ± 0.06 vs 0.56 ± 0.05), and epididymis sperm count (4.88 ± 0.92 ×109/g vs. 2.27 ± 0.69 ×109/g) in the SH group were significantly higher than those in the RS group (P < 0.05). SH reduced the mtDNA relative copy number (P < 0.01) in the testis and increased the total antioxidant capacity (3.41 ± 0.94 U/mg prot vs. 1.54 ± 0.38 U/mg prot, P = 0.05). RNA sequencing results showed 50 differentially expressed genes, with 27 genes upregulated and 23 genes downregulated in the SH group compared with the RS group. KEGG analysis revealed that the pathways related to polyunsaturated fatty acid metabolism, and vitamin digestion and absorption were enriched. The findings suggest that feeding SH in the early reproductive development stage of lambs is more beneficial for testis development and spermatogenesis compared with feeding RS.