Accumulating evidence indicates that cold exposure changes the composition of the gut microbiota and reduces intestinal immunity in early postweaning livestock. However, little is known about the effects of drinking warm water (WW) on gut microbiota during winter. In this study, we investigated the effects of drinking WW in winter on the growth performance and gut microbiota structure of rabbits raised in poorly insulated housing from the early postweaning period (day 46) to the subadult period (day 82). The average daily gain and feed conversion ratio in rabbits drinking WW were significantly improved compared to those of the rabbits drinking cold water (CW) during 47–58 days. In addition, rabbits drinking WW had a significantly decreased the risk of diarrhea during 71–82 days. 16S rRNA sequence analysis revealed that the alpha diversity of the cecal microbiota was not significantly different between the WW and CW groups, but significantly increased with age. The relative abundance of cecal microorganisms, such as Coprococcus spp. was considerably increased at day 70 in the group drinking WW. Correlation analysis indicated that Coprococcus spp. was negatively associated with pro-inflammatory factors. In conclusion, our results suggest that drinking WW has a positive effect on growth performance and gut microbiota in rabbits during the early postweaning stage in winter.

The effect of different cross-fostering strategies on the growth performance, stress and immunity of piglets was investigated in this study. In the first experiment, a total of 20 litters (i.e., 20 sows) and 120 piglets were classified into one of six treatments in a 2 × 3 factorial arrangement. The treatments consisted of piglets without or with cross-fostering and different birth weights (low birth weight, LBW; intermediate birth weight, IBW; high birth weight, HBW). The weaning weight (WW) and average daily gain (ADG) of LBW piglets and IBW piglets were not significantly different between the not cross-fostered (NC-F) group and the cross-fostered (C-F) group. There was a higher (p < 0.05) ADG in the control piglets compared with the cross-fostered piglets. This effect on ADG was only seen in the HBW piglets. In the second experiment, six sows with a similar body condition and farrowed on the same day were selected. Three female piglets with a birth weight of 0.6–0.85 kg were selected from each litter as experimental piglets. Eighteen piglets were grouped into three treatments: (1) not cross-fostered (NC-F1), (2) cross-fostered at 36–48 h after birth (C-F1), (3) cross-fostered at day 7 after birth (C-F2). The growth performance of NC-F1 and C-F1 piglets was higher than C-F2 piglets (p < 0.05), and the suckling positions of NC-F1 and C-F1 piglets on days 8, 12, 16 and 20 were more forward than the C-F2 piglets (p < 0.05). Plasma cortisol (COR) concentrations of NC-F1 and C-F1 piglets were lower than C-F2 piglets (p < 0.05). A significant negative correlation was observed between BW at day 21 and plasma COR concentration. In conclusion, cross-fostering within 24 h of birth has adverse influences on the ADG of HBW piglets, while it has no negative effect on the ADG of LBW and IBW piglets. Moreover, for IBW piglets, late cross-fostering (i.e., on day 7 after farrowing) has negative impacts on the growth performance and teat order of piglets, and it increases the cortisol level of piglets.

Maximizing the utilization of renewable energy for heating is crucial for reducing energy consumption in pig houses and enhancing energy efficiency. However, the mismatch between peak solar radiation and peak heat load demand in nursery pig houses results in energy waste. Therefore, we investigated a flexible air-source heat pump system (F-ASHP) based on the hourly-scale energy transfer of solar energy. A theoretical calculation model for F-ASHPs in pig houses in the heating areas of northern China has been established through on-site testing and Simulink. This study investigated the heat storage and release of four energy storage materials in pens and the variation in heat load in the house, validating the accuracy of the model. The results show that the F-ASHP can effectively match the peak solar heat and peak heat load in the house. Among the four energy storage materials in pens, the magnesium oxide heat storage brick material performed the best. During intermittent solar periods, it released 3319.20 kJ of heat, reducing the heat load in the pig house by 10.1% compared with that by the air-source heat pump (ASHP). This study provides a theoretical model for flexible heating calculations in pig houses in northern China and aims to serve as a valuable resource for selecting energy-storage pens.

The present study investigated the effects of low-protein (LP) diets on growth performance, intestinal morphology, apparent ileal digestibility (AID), and jejunal amino acid (AA) transporter mRNA expression in heat-stressed Pekin ducks. A total of 108 fourteen-day-old male ducks were randomly allotted to three treatments, each with six replicates of six birds: a thermoneutral (TN) group fed a control (CON) diet, a heat stress (HS) group fed the CON diet, and an HS-LP group fed the LP diet. Ducks were maintained at 22 °C (TN) or 30 °C (HS and HS-LP) for 3 wk. The CON and LP diets contained 17.5% and 16.0% CP, respectively, with similar AA profiles. Compared with the TN group, the HS group showed reduced BW, ADFI, and ADG and increased F:G (p < 0.05). Compared with the HS group, the HS-LP group showed higher BW and ADG and lower F:G (p < 0.05), although BW and ADG remained lower than in the TN group. HS decreased villus height (VH), jejunal villus height-to-crypt depth (VH:CD) ratios, and goblet cell counts (p < 0.05). Compared with the HS group, the HS-LP group showed higher jejunal and ileal VH:CD ratios and lower ileal CD (p < 0.05), whereas VH and goblet cell counts were not restored to TN values. Although AID of CP and AAs did not differ between the TN and HS groups, the HS-LP group showed higher AID of CP and AAs than the HS group (p < 0.05). In addition, the HS-LP group showed lower PEPT1 and higher LAT1 mRNA expression (p < 0.05). In conclusion, a reduction in dietary CP from 17.5% to 16.0% partially alleviated HS-induced growth depression and intestinal morphological impairment and was accompanied by increased AID of AAs and altered mRNA expression of jejunal AA transporters.