Leizhou goats are famous for their delicious meat but have inferior growth performance. There is little information on rumen-protected fat (RPF) from the Leizhou goat. Hence, we observed the effects of RPF on growth, fecal short-chain fatty acids, and bacteria community with respect to Leizhou goats. Twelve goats (13.34 ± 0.024 kg) were selected and assigned randomly to one of two treatments: (1) a control diet (CON) and (2) 2.4% RPF with a control diet (RPF). The final body weight and average daily gain (ADG) were greater (p < 0.05), and the dry matter intake (DMI): ADG was lower (p < 0.05) in the RPF group than in the CON group. There were no differences in DMI between the CON and RPF groups. The concentrations of total short-chain fatty acids, acetate, propionate, and butyrate were lower (p < 0.05) in the RPF group than in the CON group. The relative abundances of Ruminococcus, Rikenellaceae_RC9_gut_group, Treponema, norank_f__norank_o__RF39, Eubacterium_siraeum_group, and Ruminococcus_torques_group were lower (p < 0.05) in the RPF group than in the CON group. The relative abundances of Bacteroides, norank_f__norank_o__Clostridia_UCG-014, norank_f__Eubacterium_coprostanoligenes_group, Eubacterium_ruminantium_group, norank_f__Oscillospirale-UCG-010, Oscillospiraceae_UCG-002, and Family_XIII_AD3011_group were greater (p < 0.05) in the RPF group than in the CON group. It was concluded that RPF could improve the goats’ growth performance by regulating their fecal bacteria communities.

The plectin (PLEC) gene is crucial in regulating muscle development and maintaining the cytoskeleton. An abnormal expression of PLEC can lead to muscle atrophy and muscular dystrophy. In a previous study, we found that Leizhou black goats exhibit abundant structural variations in the PLEC gene. However, the genetic effects of these variations on growth traits and meat quality in goats are not fully understood. In this study, three PLEC copy number variations (CNVs) were identified in a population of 417 Leizhou black goats, using quantitative polymerase chain reaction (qPCR) technology. Population distribution analysis revealed a high abundance of various types of these three CNVs. PLEC mRNA was found to be highly expressed in muscle tissue and remained consistently high from 1 month to 24 months after birth. Specifically, the gain type of CNV-1 (chr14: 81056401-81064800) showed a significant association with PLEC mRNA expression in muscle tissue (p < 0.01). The sequence of CNV-1 in PLEC shares similarities with three domain superfamilies associated with muscle development and skin disease. Furthermore, there were significant differences in chest circumference, body weight, carcass weight, the cross-sectional area of the longissimus dorsi lumbar muscle, and shear stress between different types of CNV-1 (p < 0.05). Notably, goats with the CNV-1 gain type demonstrated better phenotypic values compared to those with loss and normal types. These findings suggest that PLEC CNV-1 could play a crucial role in the growth and muscle development of Leizhou black goats, making it a potential marker for assisted selection in goat breeding.

The objective of this study was to evaluate the effect of fecal bacterial community and metabolomics in goats when consuming a lower-protein diet with different energy levels. Eight healthy Leizhou goats, with 11 ± 0.78 kg of body weight, were selected and housed individually in cages. The animals were randomly allocated to a lower-protein diet that varied with four metabolites energy levels (7.01, 8.33, 9.66, and 10.98 MJ/kg DM) in a replicated 4 × 4 Latin square design. Notably, energy-dependent microbial restructuring was observed at both phylum and genus levels. At the phylum level, the relative abundances of Firmicutes and Spirochaetote increased linearly, whereas the Bacteroidota and Patescibacteria decreased linearly with increasing dietary energy levels (p < 0.05). The relative abundances of Verrucomicrobiota increased quadratically, whereas others decreased quadratically with increasing dietary energy levels (p < 0.05). At the genus level, a total of 316 bacteria were identified in the 32 fecal samples. The relative abundances of Christensenellaceae_R-7_group, unclassified_f__Lachnospiraceae, Ruminococcus, norank_o__Clostridia_UCG-014, Treponema, [Eubacterium]_siraeum_group, and [Eubacterium]_ruminantium_group increased linearly, whereas the Oscillospiraceae_UCG-005, norank_f__[Eubacterium]_coprostanoligenes_group, Prevotellaceae_UCG-004, unclassified_c__Clostridia, norank_f__Ruminococcaceae, unclassified_f__ Oscillospiraceae, and others decreased linearly with an increasing dietary energy levels (p < 0.05). In addition, the metabolomic analysis of feces showed that there are many differential metabolites in goats when consuming a lower-protein diet with different energy levels; for example, lipid metabolism and amino acid metabolic pathways were increased in MLE, MHE, and HE groups compared to the LE group. In conclusion, this study provides further information regarding the effects on fecal bacterial community composition and metabolites in goats when consuming a lower-protein diet with different energy levels.

The ANGPT1 gene plays a crucial role in the regulation of angiogenesis and muscle growth, with previous studies identifying copy number variations (CNVs) within this gene among Leizhou black goats. In this study, we investigated three ANGPT1 CNVs in 417 individuals of LZBG using quantitative PCR (qPCR), examining the impact of different CNV types on the ANGPT1 gene expression and their associations with growth and meat quality traits. Notably, the ANGPT1 CNV-1 (ARS1_chr14:24950001-24953600) overlaps with protein-coding regions and conserved domains; its gain-of-copies genotype (copies ≥ 3) was significantly correlated with ANGPT1 mRNA expression in muscle tissue (p < 0.01). Furthermore, the gain-of-copies genotype of CNV-1 demonstrated significant correlations with various phenotypic traits, including carcass weight, body weight, shear stress, chest circumference, and cross-sectional area of longissimus dorsi muscle. These findings indicate that the CNV-1 gain-of-copies genotype in the ANGPT1 gene may serve as a valuable marker for selecting Leizhou black goats exhibiting enhanced growth and muscular development characteristics, thereby holding potential applications in targeted breeding programs aimed at improving meat quality.

This study examined the effect of dietary supplementation of nano-selenium (nano-Se) on the average daily gain (ADG), fecal bacteria community, and concentrations of fecal minerals and volatile fatty acids in feedlot Hainan black goats. Eighteen goats (18.6 ± 0.69 kg) were divided randomly into three groups, with each group receiving a different level of supplementary nano-Se (n = six goats per treatment) as follows: (1) 0.0 mg (CON); (2) 0.2 mg; and (3) 0.4 mg nano-Se/kg dry matter intake (DMI). The final body weight (p = 0.012) and ADG increased linearly (p < 0.01), whereas the ratio of DMI to ADG decreased linearly (p < 0.01) with increasing dietary nano-Se levels. Fecal concentrations of Se increased linearly (p < 0.001), whereas Cu (p < 0.01), Zn (p = 0.020), and Fe (p = 0.010) decreased linearly with increasing dietary nano-Se levels. The relative abundances of Treponema (p = 0.046), norank_f__norank_o__Clostridia_UCG-014 (p < 0.01), norank_ f_norank_o__RF39 (p < 0.01), Eubacterium_siraeum_group (p < 0.001), and Family_XIII_AD3011_group (p = 0.040) increased linearly, and unclassified_f__Lachnospiraceae (p < 0.001), Rikenellaceae_RC9_gut_group (p < 0.01), Eubacterium_ruminantium_group (p = 0.021), and Prevotella (p < 0.001) decreased linearly with increasing dietary nano-Se levels. It was concluded that supplementary nano-Se could improve ADG and reduce the DMI to ADG ratio and fecal heavy metals by altering the bacterial community in feedlot goats. We recommend a dietary supplementation of approximately 0.4 mg nano-Se/kg DM for feedlot Hainan black goats, but further research is warranted to determine the precise dose and the possible contamination risks of Se.

Introduction: Rumen-protected fat (RPF) is a vital dietary energy source for dairy cows. However, the influences of RPF on rumen volatile fatty acid (VFA) content and bacterial communities in goats are poorly documented.Methods: In this study, 12 castrated male goats (body weight [BW]: 13.3 ± 0.02 kg; 6 months of age) were used as the experimental animal and then allocated into two groups (n = 6): a control group, fed a basal diet without RPF supplementation, and the RPF supplementation group, fed a basal diet with 2.4% RPF supplementation.Results: The final BW and ADG were higher (p < 0.05) and the ratio of dry matter (DM) intake to ADG was lower (p < 0.05) in the 2.4% RPF supplementation group compared with those in the control group. The 2.4% RPF supplementation group showed a higher total tract digestibility of DM, CP, OM, neutral and acid detergent fiber compared with that of the control group (p < 0.05). The proportion of acetate was higher (p < 0.05) and that of propionate was lower (p < 0.05) in the 2.4% RPF supplementation group compared with those in the control group. The relative abundances of Christensenellaceae_R-7_group, unclassified_f__Selenomonadaceae, norank_f__Selenomonadaceae, Quinella, norank_f__Bacteroidales_RF16_group, and unclassified_o__Bacteroidales were higher (p < 0.05) and those of Lachnospiraceae_NK3A20_group, norank_f__F082, Olsenella, Erysipelatoclostridiaceae_UCG-004, and Syntrophococcus were lower (p < 0.05) in the 2.4% RPF supplementation group compared with those in the control group.Discussion: In conclusion, 2.4% RPF supplementation can improve the ADG and antioxidant capacity by regulating the rumen bacterial communities and enhancing the apparent total tract digestibility in growing Leizhou goats.