Search Results (69)

Saline–alkaline soils are becoming prevalent across the globe, decreasing the availability of forage for animals and threatening sustainable animal production. This study evaluated the effects of a NaCl-supplemented alfalfa-based total mixed ration, simulating saline–alkaline soil conditions, on intake, the utilization of nutrients, antioxidant levels, and rumen fermentation. A 60-day feeding trial with 24 AOHU lambs (Australian White × Hu) compared a control diet (0.43% NaCl) with the NaCl-supplemented group (1.71% NaCl). Digestibility trials were conducted in metabolic cages for the collection of total feces and urine. Blood samples were taken at 0, 30, and 60 days for serum analysis, and slaughter samples (liver, kidney, rumen tissue, and rumen fluid) were taken for physiological, biochemical, and histological evaluation. The NaCl alfalfa-based TMR markedly increased liver and kidney weights. The rumen muscle layer thickened in the NaCl group. The ruminal ammonia nitrogen (NH₃-N), ruminal microbial crude protein (MCP) synthesis, and glucogenic/branched-chain VFAs increased, indicating enhanced proteolysis, microbial protein synthesis, and energetically efficient fermentation. Serum total protein and albumin also rose over time in the NaCl group, reflecting increased nitrogen retention, while superoxide dismutase and glutathione peroxidase activity rose considerably by day 60, reflecting increased antioxidant defense. Furthermore, nitrogen intake, digestibility, and retention were improved in the NaCl group along with augmented digestible and metabolizable energy (28.47 vs. 13.93 MJ/d and 24.68 vs. 11.58 MJ/d, respectively) and gross energy digestibility (78.13% vs. 67.10%). Although NaCl-based alfalfa TMR cannot fully emulate naturally salt-stressed forages, these results indicate that the NaCl alfalfa-based diets improved rumen fermentation, energy yields, and antioxidant enzyme activity without impairing electrolyte balance. These findings suggest that NaCl-supplemented alfalfa-based TMRs, with a salt content comparable to that of alfalfa hay grown under saline–alkaline conditions, could support environmentally sustainable meat production in salt-stressed regions. Full article

Numerous factors, including genetic, environmental, and nutritional, are involved in testicular development and spermatogenesis. However, little is known about the effects of seasonal factors on pre-sexual maturity testicular development in Hu rams, which are famous for their high fertility and year-round estrus onset. This study explored the effect of the birth season on testicular development and spermatogenesis in Hu sheep. Thirty-six 6-month-old male lambs born in summer (n = 18) and winter (n = 18) were selected for analysis. Results showed that summer-born lambs exhibited significantly higher cauda sperm density (102.65 ± 9.56 vs. 16.86 ± 2.02 × 10⁷/g), antioxidant indices such as superoxide dismutase (SOD: 6.29 ± 1.01 vs. 4.09 ± 0.25 U/mgprot), and higher expression levels of glutathione peroxidase 3 (GPX3), glutathione peroxidase 4 (GPX4), and copper/zinc superoxide dismutase (Cu/Zn-SOD) than winter-born lambs. Conversely, the malondialdehyde content (1.08 ± 0.32 vs. 2.13 ± 0.34 nmol/mgprot) was significantly lower in the summer-born group (p < 0.05) than in the winter-born group. A total of 44 differential oxylipins and 326 differentially expressed genes (DEGs) were screened by ultra-performance liquid chromatography–tandem mass spectrometry and transcriptomics, respectively. An integrated analysis of oxylipins and transcriptomics revealed that these differential molecules were enriched in metabolic pathways. Notably, downregulated DEGs (e.g., UAP1L1 and NAT8L) were significantly correlated with upregulated differential oxylipins (e.g., epoxyeicosatrienoic acids and dihydroxyeicosatrienoic acids). These results indicate that compared to the winter-born group, the testicular tissues of summer-born rams showed stronger testicular antioxidant capacity and lower lipid peroxidation at the sexual maturity stage, which contributes to spermatogenesis. Full article

The research aimed to examine the effects of fermentation and enzymatic hydrolysis of cottonseed protein on body weight changes, serum biochemistry, rumen function, intestinal health, and liver metabolism of suckling lambs. A total of twelve 7-day-old healthy male Hu sheep body weights (5.27 ± 0.48 kg) were randomly distributed into two groups. Starter feed regimens containing microbial fermentation of cottonseed protein (MFCP) or enzymatic hydrolysate of cottonseed protein (EHCP) were administered to lambs during the initial 60-day period. Results showed that compared with EHCP group, the serum glucose, ruminal acetic, propionic, butyric and valeric acids concentrations, jejunal immunoglobulin G content and mRNA expressions of Claudin 1 and Occludin, as well as the relative abundance of actinobacteriota and pseudoscardovia in the rumen were significantly increased in the MFCP group (p < 0.05), whereas an opposite trend was observed in the jejunum. α-amylase and trypsin enzymatic activities were observed between the two groups. Relative to EHCP treatment, the MFCP group exhibited 69 elevated and 103 reduced hepatic metabolites, and these metabolites displayed distinct enrichment patterns within specific metabolic networks, including fructose and mannose metabolism (p = 0.003), arachidonic acid metabolism (p = 0.017), glycerophospholipid metabolism (p = 0.036), and the cAMP signaling pathway (p = 0.047). Overall, microbial fermentation of cottonseed protein may be beneficial for strengthening intestinal barrier function and facilitating hepatic lipid metabolism and immune regulation, while enzymatic hydrolysis of cottonseed protein enhances gastrointestinal digestive enzyme activity, thereby promoting nutrient digestion of suckling lambs. Full article

Optimizing the metabolizable protein level in ruminant diets represents a promising strategy to increase nitrogen use efficiency and mitigate environmental pollution. This study explored the impacts of varying metabolizable protein (MP) levels on amino acid (AA) balance, nitrogen (N) utilization, and the ruminal microbiota in Hu lambs. Fifty-four female Hu lambs of 60 d old, with an average body weight (BW) of 18.7 ± 2.37 kg, were randomly allocated to three dietary MP groups: (1) low MP (LMP, 7.38% of DM), (2) moderate MP (MMP, 8.66% of DM), and (3) high MP (HMP, 9.93% of DM). Three lambs with similar BW within each group were housed together in a single pen, serving as one experimental replicate (n = 6). The feeding trial lasted for 60 days with 10 days for adaptation. The final BW of lambs in the MMP and HMP groups increased (p < 0.05) by 5.64% and 5.26%, respectively, compared to the LMP group. Additionally, lambs fed the MMP diet exhibited an 11.6% higher (p < 0.05) average daily gain than those in the LMP group. Increasing dietary MP levels enhanced (p < 0.05) N intake, urinary N, retained N, and percent N retained, but decreased apparent N digestibility (p < 0.05). Urinary uric acid, total purine derivatives, intestinally absorbable dietary protein, microbial crude protein, intestinally absorbable microbial crude protein, and actual MP supply all increased (p < 0.05) with higher MP values in the diet. The plasma concentrations of arginine, lysine, methionine, phenylalanine, threonine, aspartic acid, proline, total essential AAs, and total nonessential AAs were the lowest (p < 0.05) in the LMP group. In the rumen, elevated MP levels led to a significant increase (p < 0.05) in the ammonia N content. The relative abundances of Candidatus_Saccharimonas, Ruminococcus, and Oscillospira were the lowest (p < 0.05), whereas the relative abundances of Terrisporobacter and the Christensenellaceae_R-7_group were the highest (p < 0.05) in the MMP group. In conclusion, the moderate dietary metabolizable protein level could enhance growth performance, balance the plasma amino acid profiles, and increase nitrogen utilization efficiency in Hu lambs, while also altering the rumen bacterial community by increasing beneficial probiotics like the Christensenellaceae_R-7_group. Full article

Despite the known impacts of weaning on animal health, the underlying molecular mechanisms remain unclear, particularly how psychological and nutritional stress differentially affect gut health and immune function over time. This study hypothesized that early weaning exerts distinct short- and long-term effects on lamb stress physiology, immunity, and gut health, mediated by specific molecular pathways. Twelve pairs of full-sibling male Hu sheep lambs were assigned to control (CON) or early-weaned (EW) groups. Plasma stress/immune markers were dynamically monitored, and intestinal morphology, antioxidant capacity, apoptosis, and transcriptomic profiles were analyzed at 5 and 28 days post-weaning. Early weaning triggered transient psychological stress, elevating hypothalamic–pituitary–adrenal (HPA) axis hormones (cortisol, catecholamines) and inflammatory cytokines (TNF-α) within 1 day (p < 0.05); however, stress responses were transient and recovered by 7 days post-weaning. Sustained intestinal remodeling was observed in EW lambs, featuring reduced ileal villus height, increased crypt depth (p < 0.05), and oxidative damage (MDA levels doubled vs. CON; p < 0.01). Compensatory epithelial adaptation included increased crypt depth but paradoxically reduced villus tip apoptosis. The transcriptome analysis revealed significant changes in gene expression related to immune function, fat digestion, and metabolism. Key DEGs included APOA4, linked to lipid transport adaptation; NOS2, associated with nitric oxide-mediated immune–metabolic crosstalk; and mitochondrial gene COX1, reflecting energy metabolism dysregulation. Protein–protein interaction analysis revealed NOS2 as a hub gene interacting with IDO1 and CXCL11, connecting oxidative stress to immune cell recruitment. Early weaning exerts minimal lasting psychological stress but drives persistent gut dysfunction through transcriptome-mediated changes in metabolic and immune pathways, highlighting key genes such as APOA4, NOS2, and COX1 as potential regulators of these effects. Full article

This study aimed to evaluate the effects of studying the effects of the alkali metal ion complexes (AMIC) on the rumen of lambs. Eighteen 3-month-old male Hu lambs (30 ± 2.5 kg) were randomly assigned to three groups (n = 6). Dietary treatments were: control group (CG, base diet), group C1 (base diet + 0.15% AMIC), and group C2 (base diet + 0.30% AMIC). After 60 days of feeding, samples were collected for analysis. Compared with CG, rumen weight significantly increased in both C1 and C2 (p < 0.05). In C2, average daily gain (ADG), bacterial crude protein (BCP), propionic acid concentration, and rumen papillary length were significantly higher than in CG (p < 0.05). Rumen microbiota analysis showed that AMIC supplementation changed the microbial community composition, increasing the relative abundance of fiber-degrading bacteria (e.g., Prevotellaceae_UCG-001) and decreasing pathogenic Proteobacteria. In particular, rumen papillary length positively correlated with Unclassified Oscillospiraceae, Candidatus Saccharimonas, and Unclassified Clostridia vadinBB60 group. Metabolomic analysis revealed that quercetin 3-O-glucuronide levels increased in a dose-dependent manner with higher AMIC. This metabolite positively correlated with Prevotellaceae_UCG-001 abundance and ADG. At 0.30% AMIC, phospholipids PC(18:0/18:4(6Z,9Z,12Z,15Z)) and PE(18:0/16:1(9Z)) were significantly upregulated, and both positively correlated with Candidatus Saccharimonas, Unclassified Clostridia vadinBB60 group, and papillary morphology. In summary, AMIC supplementation affected metabolism by modulating the rumen microbiota, thereby promoting energy absorption and growth. The 0.30% AMIC inclusion significantly enhanced rumen papilla growth, increased the absorption area, promoted propionic acid production, reduced the acetic acid to propionic acid ratio, and ultimately improved the growth rate of Hu lambs. Thus, adding 0.30% AMIC was associated with improved growth performance. Full article

This study aimed to assess the effect of co-supplementing rumen-protected fat and rumen-protected choline on growth performance, carcass traits, and meat quality in lambs. Using a randomized experimental design, 45 weaned female Tian×Hu crossbred lambs (3 months old; average body weight: 27.34 ± 0.57 kg, mean ± SD) were randomly allocated to one of three dietary treatment groups. The three dietary treatments were as follows: a basal diet group (CON), a group receiving 2% rumen-protected fat in place of 2% barley (RPF), and a group supplemented with 2% rumen-protected fat and 0.4% rumen-protected choline, replacing 2% barley and 0.4% corn germ in the basal diet (RPFC). Compared to the CON group, neither the RPF nor RPFC treatments resulted in significant differences in growth performance (p > 0.05). However, the RPFC group showed a 5.3% increase in dry matter intake (DMI) compared to the RPF group (p < 0.05). Compared with the CON, the RPF treatment increased 69.23% the relative abundance of C18:2n-6t (p < 0.05), but the content of C17:0, C17:1, C18:1n-9c, and iso-C18:0 in Longissimus lumborum was decreased by 16.49%, 15.78%, 6.45% and 27.78%, respectively (p < 0.05). The RPFC treatment increased the relative abundance of C16:1 in Longissimus lumborum (p < 0.05). The RPF and RPFC treatments significantly increased serum levels of high-density lipoprotein (HDL) and total cholesterol compared to the CON group (p < 0.05). The RPF treatment raised HDL by 50.00% and total cholesterol by 38.03%, while the RPFC treatment increased HDL by 39.47% and total cholesterol by 26.03%. Furthermore, compared to the RPF group, the RPFC treatment led to a 13.47% increase in the 45 min b* color value of the Longissimus lumborum (p < 0.01) and a significant 45.45% reduction in the relative abundance of C18:2n-6t fatty acid in the same muscle (p < 0.05). In summary, rumen-protected choline reduces the negative effects of rumen-protected fat on feed intake in lambs and changes fatty acid profile in meat. Full article

Cold stress impacts lamb mortality, welfare, and productivity. Wool and skin insulate lambs, but the mechanisms underlying their response to colder environments remain unclear. Shorn lambs (n = 20) of similar age (8 months), of the Hulunbuir (n = 10; average 34.5 ± 0.70 kg) and Hu (n = 10; average 34.9 ± 0.79 kg) breeds, were raised at the Ecological and Agricultural Experimental Station, Gaolan, Gansu Province, People’s Republic of China (36°13″ N, 103°47″ E), at an altitude of 1780 m above sea level. These lambs were divided into four equal groups: Hulunbuir at −20 °C (HB−20), Hulunbuir at 15 °C (HB+15), Hu at −20 °C (HU−20), and Hu at 15 °C (HU+15). The groups were maintained at these temperatures in temperature-controlled facilities for 38 days. Skin tissues were analyzed with transcriptome sequencing, and selected wool and physiological traits were assessed. The HB−20 lambs had greater wool length growth (1.8 ± 0.13 vs. 1.0 ± 0.46 cm, p < 0.001) and epidermis thickness (20.0 ± 1.20 vs. 14.6 ± 0.87 μm, p = 0.006) but lower hair follicle density (33.6 ± 2.11 vs. 42.7 ± 3.06 per mm², p = 0.041), rectal temperature (38.1 ± 0.10 vs. 38.8 ± 0.04 °C, p < 0.001), and respiratory rate (15.5 ± 1.08 vs. 24.0 ± 1.89 breaths/min, p = 0.004), compared to the HB+15 lambs. Similar differences in these traits were observed with the Hu lambs at the two temperatures. Transcriptome analyses revealed the activation of pathways related to immune and endocrine systems, signal transduction, and development and regeneration, irrespective of breed at −20 °C. The TNF signaling pathway and osteoclast differentiation may play roles in cold adaptation, as they are associated with differentially expressed genes (DEGs) identified in the Hulunbuir lambs, as well as shared DEGs between both breeds. This study revealed physiological and molecular differences in lambs exposed to lower temperatures and suggests potential targets for improving cold tolerance, welfare, and productivity. Full article

Through an integrated multi-omics analysis of rumen microbial communities, muscle transcriptomes, metabolic profiles, and liver metabolic profiles, this study systematically compared high- and low-performing lambs to elucidate their divergent effects on meat quality attributes and growth development. A total of 100 male lambs with similar birth weight (3.07 ± 0.06 kg) were selected within 72 h. All test lambs were synchronized weaning at 45 days of age and uniformly fed the same diet (total mixed ration) in the same pen until 180 days of age, with ad libitum access to food and water throughout this period. Subsequently, the eight lambs with the highest (HADG) and lowest (LADG) average daily gains were slaughtered for performance evaluation and multi-omics analysis. This study found that HADG lambs increased body weight, muscle fiber diameter, eye muscle area, improved amino acid (histidine, arginine, valine, isoleucine, essential amino acid/total amino acid, and essential amino acid/nonessential amino acid), and fatty acid (linoleic acid, behenic acid, and arachidonic acid) composition enhanced rumen enzymes (pepsase, lipase, xylanase, amylase, and carboxymethyl cellulose) and promoted efficient fermentation (p < 0.05). Analysis of microbial populations indicated a notable increase in Prevotella levels within the rumen of HADG lambs. Furthermore, the rumen markers Schwartzia and Streptococcus exhibited significant correlations with differential meat quality traits. Analysis of the muscle transcriptome indicated a significant correlation between the turquoise module and host phenotypes, particularly body weight. Additionally, muscle metabolism is primarily concentrated within the black module; however, it exhibits a significant correlation with the host body phenotype in the yellow module (p < 0.05). Moreover, liver metabolites, rumen microbes, host phenotype, and muscle transcripts were significantly correlated (p < 0.05). In conclusion, the interactions among rumen microbes, muscle, and liver in lambs promote rumen fermentation, which in turn regulate muscle transcriptional activity and modify metabolic profiles in both the liver and muscle. Moreover, PCK1, SPP1, FGF7, NR4A1, DUSP5, GADD45B, etc., can be candidate genes for muscle growth and development. This finding provides a theoretical basis for further exploiting the production potential of Hu lambs. Full article

Consumers are increasingly demanding higher-quality mutton. Crossbreeding has been recognized as an effective means to improve meat quality. However, the phenomenon underlying these molecular system mechanisms remains largely unidentified. In this study, 48 male lambs aged 3 months were selected, including ♂ Hu sheep × ♀ Hu (HH, n = 16), ♂ Polled Dorset × ♀ Hu sheep F₁ hybrid lambs (DH, n = 16), and ♂ Southdown × ♀ Hu sheep (SH, n = 16) F₁ hybrid lambs, and raised in a single pen under the same nutritional and management conditions for 95 days. Then, seven sheep close to the average weight of the group were selected and fasted for 12 h prior to slaughter. By comparing the muscle fiber characteristics of the Longissimus dorsi of the three groups of sheep, and through transcriptomic and metabolomic analyses, we revealed molecular differences in the meat quality of Hu sheep crossbred with different parent breeds. The results of this study showed that muscle fiber diameter and cross-sectional area were significantly greater in the DH group than in the HH group, and collagen fiber content in the DH group was also significantly higher than in the HH group (p < 0.05). A total of 163 differential genes and 823 differential metabolites were identified in the three groups, most of which were related to muscle development and lipid metabolism. These included the AMPK signaling pathway, the PI3K-Akt signaling pathway, glycerophospholipid metabolism, and the related genes EFHB, PER3, and PPARGC1A. The results of this study offer valuable insights into the molecular mechanisms underlying the impact of crossbreeding on meat quality and provide a theoretical foundation for sheep crossbreed production. Full article

In this study, we examined the effect of xylooligosaccharide (XOS) supplementation on the growth performance, carcass characteristics, and meat quality of Hu lambs. In total, 60 Hu lambs (two months old and weighing 17.32 ± 0.81 kg) were randomly assigned to four treatment groups, each with three replicates and five lambs per replicate. The lambs were fed basal diets supplemented with 0, 1.5, 3, or 4.5 g/kg XOSs in a basal diet for 60 days, with the groups designated XOS0%, XOS1.5%, XOS3%, and XOS4.5%, respectively. The results revealed, compared to theXOS0% group, the XOS3% group presented a lower F:G during 31 to 45 d (p = 0.06). By the 60th day, the body length indices of groups XOS3% and XOS4.5% increased compared to the XOS0% group, with a significant increase observed in group XOS4.5% (p < 0.05). Additionally, the GR values of the XOS1.5%, XOS3%, and XOS4.5% groups increased significantly, and the rumen fluid pH values of the XOS3% and XOS4.5% groups increased significantly (p < 0.01). The crude fat content in the XOS1.5% and XOS4.5% groups were significantly lower (p < 0.05). The hardness, adhesiveness, elasticity, cohesiveness, and chewiness of the mutton in the XOS1.5%, XOS3%, and XOS4.5% groups were increased, although the differences were not statistically significant (p > 0.05). Correlation analysis indicates that there is a significant correlation between growth performance, carcass traits, and meat quality (p < 0.05). The factors influencing meat quality originate from the growth period and the slaughtering phase, which can be attributed to the effects of xylooligosaccharides. In conclusion, XOS had positive effects on the growth performance, carcass characteristics, and meat quality of Hu lambs. The comprehensive effect of group XOS3% was best. Considering the production cost, the 3 g/kg XOSs is identified as the optimal supplementation level for sheep. Full article

The early weaning of lambs frequently leads to weakened immunity, impaired intestinal function, and increased susceptibility to intestinal disease. Lactobacillus plays a role in regulating immunity, enhancing antioxidant capacity, and maintaining intestinal health. This study aims to isolate a strain of Lactobacillus with favorable probiotic properties from sheep feces and investigate its effects on the intestinal health of early-weaned lambs. In this study, the growth characteristics, acid production capacity, bacteriostatic capacity, bile salt tolerance, gastrointestinal fluid tolerance, self-coagulation capacity, and surface hydrophobicity of Lactobacillus isolated from sheep feces were analyzed for in vitro probiotic properties. Lactobacilli with strong probiotic properties were used for in vivo validation. A total of 72 Hu lambs were allocated into four groups: a ewe-reared group (ER), early-weaning group (EW), low-dose Lactobacillus group (LL), and high-dose Lactobacillus group (HL). Early weaning was performed in the EW, LL, and HL groups at the age of 28 days. Lactobacillus johnsonii M5 (L. johnsonii M5), isolated from sheep feces, exhibited strong probiotic properties in vitro. Feeding EW lambs with a low dose of L. johnsonii M5 significantly reduced their diarrhea rate (p < 0.05). Its supplementation increased the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC) in serum and jejunal mucosa and decreased levels of malondialdehyde (MDA) (p < 0.05). Compared to the EW group, serum immunoglobulin G (IgG) levels were significantly increased in the LL group (p < 0.05). Compared to the EW group, feeding with L. johnsonii M5 increased the content of anti-inflammatory cytokines, while reducing the content of pro-inflammatory cytokines in serum and jejunal mucosa (p < 0.05). Feeding early-weaned lambs with L. johnsonii M5 also decreased jejunal crypt depth and increased occludin and claudin-1 in jejunal mucosa (p < 0.05). These findings indicate that feeding early-weaned lambs with L. johnsonii M5 enhances their immunity and antioxidant capacity, improving intestinal health, and mitigates diarrhea in early-weaned lambs. Full article

(1) Background: Litter size is one of the most important economic traits of sheep. The FecB locus has been extensively studied due to its significant impact on litter size in Hu sheep, and BMP15 and GDF9 have also been reported as major genes associated with litter size in sheep. This study aimed to identify variants of BMP15 and GDF9 and perform an association analysis of these variants with litter size in the Hu sheep breed. (2) Methods: In this study, exons of the BMP15 and GDF9 genes were fully sequenced to identify polymorphisms in Hu sheep. Population genetic parameters and haplotype frequencies were estimated, and an association analysis between these polymorphic loci and litter size was performed. Additionally, the protein structures of the wild-type and mutated BMP15 and GDF9 genes were predicted. (3) Results: The polymorphisms of the BMP15 and GDF9 genes were investigated within their exon regions, revealing mutations at four previously reported sites: BMP15 c.31_33CTTdel and GDF9 (G2, G3, and G4) in Hu sheep, with no novel variants were detected. Genetic analysis indicated that the GDF9-G3 and GDF9-G4 loci have low polymorphisms, whereas the BMP15 c.31_33CTTdel and the GDF9-G2 locus are moderately polymorphic. The mutation sites in the BMP15 and GDF9 genes were under Hardy–Weinberg equilibrium. Association analysis revealed that the BMP15 c.31_33CTTdel and GDF9 (G2, G3, and G4) mutations are not associated with litter size in Hu sheep. Protein structure prediction indicated that the mutations in BMP15 and GDF9 resulted in alterations to their tertiary structures. (4) Conclusions: In this study, four reported mutations in the BMP15 and GDF9 genes can also be detected in the Hu sheep breed. In these mutations, the G2 and G3 mutations of GDF9 did not alter the amino acid sequence, while the BMP15 c.31_33CTTdel mutation and the GDF9 G4 mutation resulted in protein structure alteration. Furthermore, the BMP15 c.31_33CTTdel mutation and the GDF9 mutations (G2, G3, G4) were associated with an increased tendency in litter size. However, no significant difference was observed (p > 0.05). This study provides valuable insights for improving the lambing performance of Hu sheep. Full article

To improve the efficiency of prostaglandin F_2α (PG)-based estrus synchronization in sheep, this study assessed the effect of the gonadotropin-releasing hormone (GnRH) included in the long-interval PG treatment regimen for sheep estrus synchronization during the breeding season. In experiment 1, 30 multiparous Mongolian sheep (3–4.5 years old) were randomly divided into three groups. In the progesterone (P4)–equine chorionic gonadotropin (eCG) group (P4-eCG, n = 10), the ewes were synchronized with intravaginal P4 sponges for 14 days, and received an injection of 330 IU of eCG at sponge withdrawal. In the PG group (n = 10), the ewes received two doses of 0.1 mg PG with a 14 day interval. In the PG-GnRH-PG group (n = 10), the ewes were synchronized by two doses of 0.1 mg PG with a 14 day interval like that in the PG group, but received 50 μg of GnRH 7 days after the first injection of PG. It was found that, at the end of treatment, the number of corpus luteum on the ovaries and the concentration of the serum P4 in the PG-GnRH-PG group were significantly higher than that of the PG and P4-eCG groups. In experiment 2, 59 multiparous Mongolian sheep (3–4.5 years old) were assigned to three groups, like in experiment 1 (n = 20, 20 and 19 for the P4-eCG, PG and PG-GnRH-PG groups, respectively). The estrus of ewes in the PG-GnRH-PG group was more synchronous compared to the PG group. After insemination of the estrus ewes, the pregnancy rate was numerically but not significantly higher in the PG-GnRH-PG group than that in the P4-eCG and the PG groups. In a field test, 285 multiparous Hu sheep (3–4.5 years old) were randomly assigned to a P4-eCG group (n = 142) and PG-GnRH-PG group (n = 143). Timed artificial insemination showed no significant differences in the rates of pregnancy and lambing between the PG-GnRH-PG and P4-eCG groups. We conclude that the addition of GnRH in the long-interval PG protocol may improve the efficiency of PG-based estrus synchronization, and would represent a potential alternative to the conventional P4-eCG based protocol during the breeding season in sheep. Full article

This study aimed to evaluate the effect of early weaning (EW) on the growth performance, gastrointestinal development, serum parameters, and metabolomics of Hu sheep lambs. Twenty-four male Hu lambs were initially ewe-reared. A total of 12 lambs were weaned at 30 d of age (D30) as the EW group, and the remaining 12 lambs were weaned at 45 d of age (D45) as the control (CON) group. Serum samples were collected from six lambs per treatment on D30, D33, D36, and D45, and the lambs were slaughtered on D45 to collect the rumen and small intestine. The results showed that, compared with the CON group, the average daily gain (ADG), final body weight (p < 0.001), as well as average daily feed intake (ADFI) of lambs in the EW group significantly decreased in the first (p = 0.004) and second (p = 0.013) 5 days of treatment. Additionally, EW increased the ruminal weight and papillae length but reduced the duodenal villus height on D45 (p < 0.05). As for the serum parameters, the concentrations of glucose on D33, D36, and D45 (p < 0.001), and the IL-6 content on D45 (p = 0.018) were observed to be lower, while the levels of immunoglobulin A (IgA) (p = 0.027), IgG (p = 0.035), and IgM (p = 0.002) on the four ages were all higher in the EW group than those in CON group. Additionally, both treatment and age interactively affected the levels of GLU (p = 0.001), TP (p = 0.041), and IL-6 (p = 0.016). Additionally, the serum metabolomics analysis on D45 showed that the contents of 5-HT and arachidonic acid were increased, while L-phenylalanine, L-tyrosine, and L-glutamic acid were reduced in the EW group (p < 0.05). These differential metabolites were enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including inflammatory mediator regulation, protein digestion and absorption, and phenylalanine and tyrosine biosynthesis. The current results identify that EW at D30 decreased the growth performance (ADG and ADFI) of Hu lambs within two weeks post-weaning, which might be associated with impaired duodenal morphology and glucose metabolism. The serum metabolomics analysis revealed that EW altered the concentrations of 5-HT, phenylalanine, tyrosine, and arachidonic acid, which could serve as potential regulatory targets for modulating the health of EW Hu lambs. Full article