This review aims to examine the effects of the photoperiod on farm animals and to provide insights into how lighting management can optimize production performance, reproduction, and welfare. The production performance of farm animals is influenced by a variety of factors, such as diet, breed, and environment. Among these, lighting is a crucial component of the feeding environment. With the advancement of intensive farming, lighting measures are increasingly receiving attention. The photoperiod regulates the biological rhythms of animals and affects the secretion of hormones within the animal’s body, particularly melatonin. Melatonin regulates the secretion and release of several other hormones through various pathways, such as growth hormone, prolactin, and gonadotropins. Therefore, the environmental light cycle participates in a variety of physiological activities within animals. An appropriate photoperiod can enhance the production performance, reproduction performance, and welfare conditions of farm animals. Choosing the appropriate lighting duration based on different animals, physiological stages, and production purposes can enhance the economic benefits of farms. In this review, we summarized the recent findings on the impact of photoperiods in different farm animal feeding environments on animal husbandry, although research on the suitable photoperiod for some animals might be outdated and is also discussed in this article. For lactating dairy cows, calves, poultry, pigs (excluding boars), and rabbits, continuous light exposure exceeding 12 h per day can be implemented to enhance growth and production performance. In contrast, for boars and goats, daily light exposure should be limited to less than 10 h to optimize reproductive and productive efficiency. Overall, this review aimed to provide theoretical support for research on the optimal photoperiod for farm animals.

The purpose of this study was to investigate the effects of oregano essential oil on the production performance and intestinal barrier in rabbits. One hundred and ninety-two weaned Hyla rabbits (35 days old) with similar body weight (1268.5 ± 25 g) were randomly divided into four groups (24 replicates per group, two rabbits per replicate): fed a basal diet (Control group), fed a basal diet containing 0.02% oregano essential oil (LO group, the purity of oregano essential oil was 5%), fed a basal diet containing 0.04% oregano essential oil (MO group), or fed a basal diet containing 0.08% oregano essential oil (HO group). The trial included 7 days of adaptation and 23 days of testing. Although dietary addition of oregano essential oil did not affect significantly the average daily body weight and final body weight (p > .05), dietary addition of 0.08% oregano essential oil decreased significantly feed intake and diarrhoea rate of the rabbits (p < .05). When the addition of oregano essential oil in the feed reached 0.08%, the Villus high/Crypt depth value in the ileum of meat rabbits increased significantly (p < .05). Dietary addition of 0.08% oregano essential oil increased significantly the gene expression of junctional adhesion molecule 2 (JAM2) and JAM3 in jejunum (p < .05). The content of interleukin-2 (IL-2) and immunoglobulin A (SIgA) in jejunum and IL-10 and secretory immunoglobulin G (SIgG) in ileum were significantly increased after the addition of 0.08% oregano essential oil compared with the control (p < .05). In conclusion, a dietary supplement of oregano essential oil modulates immune responses and enhances the intestinal barrier. Besides, our experiment offers positive evidence in improving rabbit health of oregano essential oil instead of antibiotics.

The purpose of this study was to investigate the effects of sodium butyrate as a substitute for antibiotics on the production performance and intestinal barrier of meat rabbits. Six hundred healthy weaned rabbits were randomly divided into three groups (40 replicates per group): fed a basal diet (control), fed a basal diet containing 0.5% sodium butyrate (sodium butyrate), or fed a basal diet containing 0.004% antibiotics (antibiotic). The trial included 7 days of adaptation and 28 days of testing. After adding sodium butyrate to the feed, the mortality and diarrhoea rates of the weaned meat rabbits were reduced, and the composition of their intestinal flora was improved. Treatment significantly increased the villus height of the ileum (p < .05), decreased the crypt depth of the jejunum, and increased the V/C ratio of intestinal tissue. The contents of IL-4, IFN-gamma and SIgA in the intestinal tissue were significantly increased, indicating improvement of the intestinal immune barrier. The expression of occludin in the duodenum also increased significantly. To sum up, sodium butyrate can be added to the diet of growing meat rabbits instead of antibiotics. The physical barrier, immune barrier and microbial barrier of rabbit intestine were improved. Rabbit farmers can use sodium butyrate to prepare a new type of eco-friendly feed.

High stocking density and suboptimal conditions limit animal behaviors in modern livestock farming. This is particularly evident in captive animals, in which the motivation for foraging behavior is often thwarted. Oral stereotypic behaviors are common in farm animals. Ruminants (e.g., cattle and sheep) show oral stereotypic behaviors such as tongue‐rolling, self‐sucking, and inter‐sucking. Captive pigs exhibit oral stereotypic behaviors such as bar‐biting, sham‐chewing, and ear‐biting. Chickens peck at drinkers, feeders, and pens. Stereotypic behavior in livestock can be reduced by selecting a specific diet composition that prolongs their eating time and increases their satiety. Furthermore, reducing stocking density and enriching the farming environment encourage livestock to explore and reduce stereotypic behavior. It is important to note that stereotypic behavior is also influenced by organismal physiology. Stereotypic behavior was considered an indicator of poor animal welfare. However, recent research has revealed that animals engage in stereotypic behavior as a response to external stimuli, aiming to alleviate the negative impact of these stimuli on their well‐being. Animals that frequently show stereotypic behavior may have higher levels of stress. Certain stress indicators also affect the expression of stereotypic behavior, such as 5‐hydroxytryptamine and dopamine. Consequently, further investigation is necessary to understand how stereotypic behaviors affect the physiological state and metabolic processes of animals. This paper discusses the research progress on the oral stereotypic behaviors of farm animals. The objective is to establish a foundation for enhancing livestock feeding conditions and optimizing feeding practices, ultimately reducing stereotypic behaviors.