The objective of this experiment was to study the effects of partial replacement of soybean meal (SBM) with canola meal (CM) or corn-distillers' dried grains with solubles (cDDGS) in reduced-protein (RP) diets for Eimeria-infected broilers. A total of 1120 broiler chicks were distributed in a 4 × 2 (4 diets × with or without infection) factorial arrangement with 7 replicates per treatment and 20 birds per replicate. The 4 diets, fed between d 7 and 42, were (i) a standard diet with crude protein at 200 g/kg (SP); (ii) a RP (crude protein at 160 g/kg) corn-SBM diet (RP-SBM); (iii) a RP diet in which 80 g/kg CM replaced 60 g/kg SBM (RP-CM); and (iv) a RP diet in which 100 g/kg cDDGS replaced 50 g/kg SBM (RP-cDDGS). On d 15, birds were infected with mixed Eimeria (+E) oocysts. Birds and feed were weighed at intervals for growth performance, and samples for immunology responses were collected on d 21. The results showed as follows: 1) during the acute infection phase, diet × Eimeria infection was shown by the diets having no effect in the uninfected group. In contrast, the RP-SBM diet tended to produce higher (P < 0.10) weight gain among the infected birds. The d 42 body weight was greater (P = 0.001) for the uninfected birds. 2) There was a significant diet × Eimeria infection on bile anti-Eimeria immunoglobulin A (IgA) concentrations (P = 0.015), splenocyte proliferation, macrophage nitric oxide (NO) production (P < 0.001), and cecal tonsil interleukin (IL)-17 mRNA amounts (P < 0.001). Most of these responses were not influenced by the diets in the uninfected birds. However, among the infected birds, birds fed RP-SBM had higher (P < 0.05) bile IgA than those fed SP or RP-cDDGS. For the spleen, the interaction was that birds fed RP-SBM or RP-cDDGS diets had the highest or lowest NO production, respectively, and birds that received RP-SBM had greater (P < 0.05) splenic CD⁸⁺:CD⁴⁺ cell ratio than other diets. In conclusion, partial replacement of SBM with CM or cDDGS had only a marginal effect on d 42 body weight and FCR of the broiler chickens receiving the RP diets. In contrast, these had a negative impact on the immune responses of the broiler chickens.

Alfalfa is primarily stored as silage or hay in livestock production. Previous research has shown that the storage method of grass significantly influences milk composition. This study aimed to investigate milk production performance and lipid composition in dairy cows fed diets consisting of alfalfa hay or alfalfa silage as roughage. Forty-two mid-lactation Holstein dairy cows were selected and randomly divided into three groups, each receiving a total mixed ration consisting of alfalfa hay (AH), 50% alfalfa silage + 50% alfalfa hay (AHAS), or alfalfa silage (AS). The results showed that milk fat content (P = 0.049) and milk fat yield (P < 0.001) were significantly higher in the AH and AHAS groups compared to the AH group. With increased supplementation of alfalfa silage in the diet, ω-3 polyunsaturated fatty acid content increased significantly (P < 0.001), while ω-6 polyunsaturated fatty acid content (P = 0.007) and the ratio of ω-6 to ω-3 polyunsaturated fatty acids decreased (P < 0.001). The contents of sphingomyelins, phosphatidylserines, phosphatidylethanolamines, and phosphatidylglycerols in the AHAS and AS samples were higher than in the AH samples, although the differences were not statistically significant. Additionally, the content of phosphatidylcholines was significantly higher in the AS group compared to the AH group (P = 0.032). In conclusion, feeding dairy cows a diet consisting of alfalfa silage can increase the major phospholipid content and polyunsaturated fatty acid composition in raw milk, which is more conducive to human health. These findings provide valuable insights into the benefits of alfalfa silage for dairy cows.

This study aimed to develop a compensatory growth model using growing beef cattle by changing dietary protein and to investigate the underlying mechanisms of compensatory protein deposition in muscle tissue. Twelve Charolais bulls were randomly assigned to one of two groups with two periods: 1) a control group (CON) fed a 13% crude protein (CP) diet for 6 weeks; 2) a treatment group (REC) fed a 7% CP diet for 4 weeks (restriction period) and fed a 13% CP diet in the following 2 weeks (re-alimentation period). Growth performance, digestibility, nitrogen balance, targeted metabolomics of amino acids (AA) in plasma, and transcriptional profiling in muscle tissue were analyzed. Protein restriction decreased average daily gain (ADG; P < 0.05), while protein re-alimentation increased ADG relative to the CON (P < 0.05). Compared to the CON, REC reduced retained N (P < 0.05), and protein re-alimentation increased retained N and N utilization efficiency (P < 0.05), due to reduced urinary urea, hippuric acid, and creatinine excretions (P < 0.05). Ruminal NH₃-N in the REC was lower than that in the CON in the protein re-alimentation period (P < 0.05). However, there was no difference in microbial protein and plasma urea nitrogen concentrations. Dietary protein restriction decreased plasma valine and aspartic acid concentrations relative to the CON (P < 0.05), and increased proline and 3-methyl-L-histidine concentrations (P < 0.05). After dietary protein re-alimentation, REC increased plasma citrulline concentrations (P < 0.05). The transcriptional profiling revealed that REC upregulated the AA transporter SLC3A1, and protein re-alimentation downregulated SLC7A8 in the muscle cell membrane. Within the muscle cell, upregulated cytosolic arginine sensor for mTORC1 subunit 2 (CASTOR2) inhibited protein synthesis by inhibiting the mammalian target of rapamycin complex 1 phosphorylation in the protein restriction period, while DNA-damage-inducible transcript 4 (DDIT4) activated the mTOR signaling pathway and promoted protein synthesis in the protein re-alimentation period. In summary, the targeted metabolomics and transcriptomics analyses demonstrated that protein re-alimentation following restriction can promote protein synthesis and reduce muscle breakdown by regulating AA metabolism and functional transcripts related to AA transporters and the mTOR signaling pathway.

This study investigated whether vitamin A (VA) administration during the neonatal stage could increase the number of intramuscular adipocytes in Hu sheep by promoting vascularity. A total of 56 newborn male Hu sheep were divided into four groups and received intramuscular injections of either 0, 7500 IU retinoic acid (RA), 7500 IU VA, or a combination of 7500 IU VA and 5 mg SU5416 (an angiogenic inhibitor), at 1, 7, 14, and 21 days of age. At 15 days of age, 6 sheep from each group were randomly selected and sacrificed for intramuscular adipogenic capacity analysis. The remaining 8 sheep in each group were raised until they were 8 months old. VA-treated sheep exhibited an increase in preadipocytes, elevated expression of adipogenic genes (CCAAT enhancer binding protein alpha [CEBPA] and CCAAT enhancer binding protein beta [CEBPB]) and angiogenic genes (vascular endothelial growth factor A [VEGFA]), and stromal vascular fraction cells in the longissimus dorsi (LD) muscle with enhanced adipogenic capacity (P < 0.05). These effects were entirely negated by SU5416. Upon slaughter, VA increased final weight, carcass weight, and average daily gain (P < 0.05) but did not affect feed intake at 21 to 32 weeks (P = 0.824). VA increased the number of intramuscular adipocytes in the LD and semitendinosus (ST) muscle (P < 0.05) without changing the adipocyte number of the omentum, perirenal and subcutaneous fats (P > 0.05). VA injections also increased intramuscular triglyceride (TG) content (P = 0.016) without changing the omentum fat weight or subcutaneous fat thickness (P > 0.05), but it did increase the perirenal fat weight (P = 0.011). Consistently, SU5416 mitigated the effects of VA on intramuscular TG content and adipocyte count, correlating with a decrease in vascularity. In contrast, RA injections didn't affect the intramuscular fat (P = 0.744) but reduced the TG content of the omentum and perirenal fat (P < 0.05). In conclusion, intramuscular injections of VA but not RA at the neonatal stage improved the growth performance of Hu sheep, increasing the number of intramuscular adipocytes and marbling by promoting angiogenesis.

A 10-week feeding trial, followed by 24-h nitrite stress, was performed to evaluate the effects of dietary selenium-L-methionine (Se-Met) on growth, Se accumulation, antioxidant capacity, transcripts of selenoproteins and histological changes of muscle as well as resistance to nitrite stress in spotted seabass (Lateolabrax maculatus) reared at optimal (27℃) and high (33℃) temperatures. Five experimental diets were formulated to contain Se-Met at 0, 0.9, 1.8, 3.5, and 7.0 mg/kg. Each diet was fed to fish (2.60 ± 0.2 g) in two parallel treatments at 27 or 33℃. The results showed that elevated temperature (33℃) induced thermal stress in fish, and fish under thermal stress exhibited lower weight gain and hepatosomatic index but a higher condition factor compared to those reared at 27℃. However, the growth and feed utilisation were promoted in L. maculatus with 0.9 to 3.5 mg/kg Se-Met treatments. The protein and lipid content in the muscle increased with the dietary Se-Met level, and the total Se level in the whole body and muscle showed a linear increase with dietary Se-Met supplementation. Thermal stress changed the histology of the muscle, leading to raised levels of malondialdehyde (MDA), reduced antioxidant parameters in the serum and liver, and a decrease in the transcripts of selenoprotein genes in the muscle. Meanwhile, increased antioxidant capacity of serum and liver and up-regulated transcripts of selenoprotein of muscle were observed in L. maculatus reaching a maximum with 3.5 mg Se-Met/kg treatment. After 24 h of nitrite stress, thermal stress exacerbated oxidative damage caused by nitrite stress in L. maculatus. In contrast, dietary Se-Met enhanced the resistance to nitrite stress of L. maculatus fed with Se-Met enriched diets containing 0.9 to 1.8 mg Se-Met/kg. Based on the effects of dietary Se-Met on the growth, antioxidant capacity and resistance to nitrite stress of L. maculatus, this study suggests that the optimal range of Se-Met supplementation in L. maculatus diets is 1.80 to 2.39 mg Se-Met/kg of diet at 27℃ and 1.80 to 4.46 mg Se-Met/kg of diet at 33℃.

Heat stress poses a significant threat to the global livestock industry, particularly impacting dairy cows due to their higher metabolic heat production and increased susceptibility. The rumen microbiota plays a crucial role in regulating heat stress in dairy cows. Moreover, the rumen-mammary gland axis has been recently unveiled, indicating that rumen bacteria and their metabolites can influence mammary gland health and function. Extracellular vesicles, cell-derived vesicles, are known to carry various biomolecules and mediate intercellular communication and immune modulation. This review proposes the hypothesis that heat stress poses a threat to dairy cows via the rumen-mammary gland axis by regulating rumen microbiota and their secreted extracellular vesicles. It summarizes existing knowledge on bacterial extracellular vesicles and the rumen-mammary gland axis, suggesting that targeting the rumen microbiota and their extracellular vesicles, while enhancing mammary gland health through this axis, could be a promising strategy for preventing and alleviating heat stress in dairy cows. The aim of this review is to offer new insights and guide future research and development efforts concerning heat stress in dairy cows, thereby contributing to a deeper understanding of its pathogenesis and potential interventions.

In recent years, marine macroalgae have been recognized as potential alternative and sustainable feeding resources for livestock. Differences in nutritional values and biomass yield across macroalgal species are critical factors while aiming to utilize them as animal feed components. A brown macroalga, Saccharina latissima, also known as sugar kelp, has a promising biomass yield and high nutritional and bioactive compounds that can benefit both ruminant and monogastric animals. For example, the dietary inclusion of S. latissima in dairy and beef cattle can enhance milk yield, meat quality, and iodine content in milk and meat while reducing enteric methane emissions in vitro. However, high iodine content and the presence of some potentially toxic elements (arsenic, cadmium, etc.) lead to critical challenges, demanding careful consideration while determining the inclusion level of S. latissima in the livestock feed. To address these challenges, effective post-harvest biomass processing techniques, particularly hydrothermal treatments, have shown promise in reducing heavy metals and minerals of concern (e.g., iodine) and enhancing their safety as animal feed. It is thus essential to evaluate the sustainability of post-harvest processing techniques as they are usually energy-demanding and can negatively influence nutrient utilization in animals as certain digestible fractions can disappear during processing. Furthermore, variations in the nutritional and bioactive composition of S. latissima due to seasonal and spatial factors can create challenges for commercial exploitation. In this context, multiple harvesting of biomass and choosing the appropriate harvesting seasons can maximize the nutritional potential of S. latissima. In conclusion, S. latissima can be a novel feed ingredient for livestock, but year-round biomass availability and identifying cost-effective and energy-efficient post-harvest biomass processing methods that optimize both nutritional values and digestibility of S. latissima are critical for improving animal production, performance, and health.

With the increasing incorporation of plant-based ingredients into the grouper diet, the issue of aflatoxin B1 (AFB1) contamination in the diet has become a significant concern. In this study, the negative effects of AFB1 on the growth and liver health of hybrid groupers (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂) were investigated in the context of growth, liver histology, serum biochemical indices, and integrated transcriptomic and metabolomic data. A total of 540 healthy hybrid groupers, initially weighing 11.59 ± 0.03 g, were randomly divided into six groups (three replicates of 30 fish each): the control group was fed a basal diet, and the experimental groups were supplemented with 7 (AF7), 30 (AF30), 111 (AF111), 445 (AF445) and 2230 μg/kg AFB1 (AF2230) in the basal diet respectively, for 56 days. Groups control, AF445, and AF2230 were selected for subsequent histological, muscle fatty acid, and transcriptomic and metabolomic analyses based on the results of hybrid grouper growth and serum biochemical indices. Compared to the control group, both whole-body crude lipid and muscle crude lipid contents showed significant decreases in the AF2230 group (P < 0.05), while only muscle crude lipid content showed a significant decrease in the AF445 group (P = 0.001). Liver damage was seen in the histology of the liver of AF445 and AF2230 groups. Muscle fatty acid results showed that the addition of 445 and 2230 μg/kg AFB1 to the diets increased saturated fatty acids and monounsaturated fatty acids and decreased polyunsaturated fatty acids and highly unsaturated fatty acids in muscle (P < 0.05). Transcriptome analyses revealed multiple metabolic pathways associated with AFB1 metabolism, and metabolomics analyses further confirmed changes in the activity of these pathways. The results of the combined transcriptomic and metabolomic analyses indicated that AFB1 causes liver injury mainly by affecting liver retinol metabolism, metabolism of xenobiotics by cytochromes P450, drug metabolism-cytochromes P450 and biosynthesis of unsaturated fatty acids. In conclusion, dietary AFB1 levels above 445 μg/kg resulted in growth inhibition, liver injury, liver AFB1 accumulation, and reduced muscle polyunsaturated fatty acid content in groupers, thereby affecting muscle quality. This study provides novel insights into the detrimental effects of AFB1 on aquatic species and contributes to the scientific basis for the health and sustainability of aquaculture practices.

Newborn goat kids exposed to environmental stress are susceptible to diarrhea due to immature intestinal functions and undeveloped gut microbiota. Butyrate-producing bacteria as next generation probiotics benefit the maintenance of intestinal health, but the mode of regulation is still unclear. Herein, a novel butyrate-producing strain was isolated from sheep rumen and identified as Clostridium beijerinckii (C. beijerinckii) R8, thereafter goat kids were treated with C. beijerinckii R8 to elucidate its regulatory mechanisms on diarrhea. Thirty-six goat kids were assigned to four groups: control (CON), low dose (LCB; supplementation with 5 × 10⁷ CFU/mL of C. beijerinckii R8, each with 10 mL/d), middle dose (MCB; supplementation with 5 × 10⁸ CFU/mL of C. beijerinckii R8, each with 10 mL/d), high dose (HCB; supplementation with 5 × 10⁹ CFU/mL of C. beijerinckii R8, each with 10 mL/d). The experiment lasted for 15 d, and 6 goat kids were randomly selected from each group for slaughter on the last day of the trial. The results showed that this isolate reduced the diarrhea rate (P < 0.001) and fecal scores (P < 0.001). In the gut, its supplementation inhibited inflammation, increased antioxidant capacity, and regulated intestinal flora. Meanwhile, C. beijerinckii R8 strengthened the intestinal barrier and altered the jejunum morphology. This evidence suggests that C. beijerinckii R8 may alleviate diarrhea in goat kids by regulating microbiota, which is directly related to intestinal barrier and immune capacity.

The posterior intestinal microbiota plays a vital role in the growth and health of Holstein dairy calves. However, its establishment and dynamic changes during early development remain unclear. The aim of this study was to investigate microbial colonization and development in the rectum of calves within the first 70 d after birth. Here, 96 rectal content samples were collected from 8 Holstein dairy calves at 12 time points and analyzed using 16S rRNA gene sequencing. The microbial alpha diversity increased with age. The bacterial community displayed a distinct dynamic distribution. The phylum Proteobacteria was replaced by Firmicutes and Bacteroidetes after d 3. The colonization process of bacterial genera in the rectum of neonatal calves can be divided into 2 periods: the colonization period (stage 1: d 1 and stage 2: d 3) and the stable period (stage 3: d 7–14, stage 4: d 21–42, and stage 5: d 49–70). The fermentation pattern and metabolic function changed from propionate fermentation dominated by Shigella to lactic acid fermentation dominated by Lactobacillus, Blautia, and Oscillospira. The stable period was more comprehensive and complete than the colonization period. This study revealed the dynamic changes in the posterior intestinal microbiota of Holstein dairy calves during early development. The transition period (d 7–14) was identified as a key stage for early nutritional intervention, as the abundance of Lactobacillus increased and the abundance of harmful bacteria (such as Proteobacteria and Shigella) decreased. This study provides a framework for understanding early-life gut health and offers theoretical guidance for future research on host–microbe interactions and early nutritional interventions. It is suggested that nutritional interventions based on microbial characteristics at different stages be implemented to improve calf growth performance and immune function, which may contribute to the reduction of diarrhea and other gastrointestinal disorders during dairy production.