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Reactive oxygen species (ROS) can be caused by mechanical, thermal, infectious, and chemical stimuli, and their negative effects on the health of humans and other animals are of considerable concern. The nuclear factor (erythroid-derived 2)-like 2/Kelch-like ECH-associated protein 1 (Nrf2/Keap1) system plays a major role in maintaining the balance between the production and elimination of ROS via the regulation of a series of detoxifying and antioxidant enzyme gene expressions by means of the antioxidant response element (ARE). Dietary phytochemicals, which are generally found in vegetables, fruits, grains, and herbs, have been reported to have health benefits and to improve the growth performance and meat quality of farm animals through the regulation of Nrf2-mediated phase II enzymes in a variety of ways. However, the enormous quantity of somewhat chaotic data that is available on the effects of phytochemicals needs to be properly classified according to the functions or mechanisms of phytochemicals. In this review, we first introduce the antioxidant properties of phytochemicals and their relation to the Nrf2/Keap1 system. We then summarize the effects of phytochemicals on the growth performance, meat quality, and intestinal microbiota of farm animals via targeting the Nrf2/Keap1 system. These exhaustive data contribute to better illuminate the underlying biofunctional properties of phytochemicals in farm animals.
Low protein intake causes a decrease in protein deposition in most animal tissues. The purpose of this study was to investigate whether leucine supplementation would increase the synthesis rate of protein and muscle weight in adult rats, which chronically consume only 58.8% of their protein requirements. Thirty-six male Sprague-Dawley rats were assigned to one of three dietary treatments including a 20% casein diet (CON), a 10% casein+ 0.44% alanine diet (R), and a 10% casein+ 0.87% leucine diet (RL). After a 10 d dietary treatment, plasma amino acid levels were measured after feeding, the gastrocnemius muscles and soleus muscles were harvested and weighed, and the fractional synthesis rate (FSR) and mammalian target of rapamycin (mTOR) signaling proteins in skeletal muscle were measured. Regarding the plasma amino acid level, the RL group had the highest concentration of leucine (P<0.05) and the lowest concentration of isoleucine (P<0.05) among the three groups, and the CON group had a lower concentration of valine (P<0.05) than the R and RL groups. Compared with the R and RL groups, the CON group diet significantly increased (P<0.05) feed intake, protein synthesis rate, and the phosphorylation of eukaryotic initiation factor 4E binding protein 1 (4E-BP1), and decreased the weight of abdominal adipose. Compared with the R group, the RL group significantly increased in gastrocnemius muscle weight, protein synthesis rate, and phosphorylation of both ribosomal protein S6 kinase 1 (S6K1) and 4E-BP1. In conclusion, when protein is chronically restricted in adult rat diets, leucine supplementation moderately improves body weight gain and increases muscle protein synthesis through mTOR activation.
The invention and development of new research concepts, novel methodologies, and novel bioanalytical techniques are essential in advancing the animal sciences, which include feed and nutrition science. This article introduces a novel approach that shows the potential of advanced synchrotron-based bioanalytical technology for studying the effects of molecular structural changes in feeds induced by various treatments (e.g., genetic modification, gene silencing, heat-related feed processing, biofuel processing) in relation to nutrient digestion and absorption in animals. Advanced techniques based on synchrotron radiation (e.g., synchrotron radiation infrared microspectroscopy (SR-IMS) and synchrotron radiation X-ray techniques) have been developed as a fast, noninvasive, bioanalytical technology that, unlike traditional wet chemistry methods, does not damage or destroy the inherent molecular structure of the feed. The cutting-edge and advanced research tool of synchrotron light (which is a million times brighter than sunlight) can be used to explore the inherent structure of biological tissue at cellular and molecular levels at ultra-high spatial resolutions. In conclusion, the use of recently developed bioanalytical techniques based on synchrotron radiation along with common research techniques is leading to dramatic advances in animal feed and nutritional research.
Due to increasing safety concerns regarding human consumption of fish products, an increasing number of medicinal chemicals are prohibited from use in aquaculture. As a result, Chinese herbal medicines are being increasingly used, coining the use of the term “green medicine.” Research shows that Chinese herbal medicines have many beneficial effects on fish, including growth promotion, enhancement of disease resistance, and improvement in meat quality. Many effective ingredients have been discovered in Chinese herbal medicines, which function to promote feed intake, improve meat flavor, and increase digestive enzyme activity. They also regulate and participate in processes that improve the specific and non-specific immunity of fish; however, the composition of Chinese herbal medicines is very complex and it is often difficult to identify the effective ingredients. This article reviews the latest research and application progress in Chinese herbal medicines regarding growth and feed utilization, immunity and disease resistance, and the meat quality of cultured fish. It also discusses research on the chemical constituents of classical Chinese medicinal herbs and problems with the application of Chinese herbal medicines in fish culture. This article concludes by proposing that future studies on Chinese herbal medicines should focus on how to cheaply refine and extract the effective ingredients in classical Chinese medicinal herbs, as well as how to use them efficiently in aquaculture.
At present, substantial amounts of low-cost, fibrous co-products are incorporated into pig diets to reduce the cost of raising swine. However, diets that are rich in fiber are of low nutritive value because pigs cannot degrade dietary fiber. In addition, high-fiber diets have been associated with reduced nutrient utilization and pig performance. However, recent reports are often contradictory and the negative effects of high-fiber diets are influenced by the fiber source, type, and inclusion level. In addition, the effects of dietary fiber on pig growth and physiological responses are often confounded by the many analytical methods that are used to measure dietary fiber and its components. Several strategies have been employed to ameliorate the negative effects associated with the ingestion of high-fiber diets in pigs and to improve the nutritive value of such diets. Exogenous fiber-degrading enzymes are widely used to improve nutrient utilization and pig performance. However, the results of research reports have not been consistent and there is a need to elucidate the mode of action of exogenous enzymes on the metabolic and physiological responses in pigs that are fed high-fiber diets. On the other hand, dietary fiber is increasingly used as a means of promoting pig gut health and gestating sow welfare. In this review, dietary fiber and its effects on pig nutrition, gut physiology, and sow welfare are discussed. In addition, areas that need further research are suggested to gain more insight into dietary fiber and into the use of exogenous enzymes to improve the utilization of high-fiber diets by pigs.
Although the effect of animal and diet factors on enteric methane (CH4) emissions from confined cattle has been extensively examined, less data is available regarding CH4 emissions from grazing young cattle. A study was undertaken to evaluate the effect of the physiological state of Holstein-Friesian heifers on their enteric CH4 emissions while grazing a perennial ryegrass sward. Two experiments were conducted: Experiment 1 ran from May 2011 for 11 weeks and Experiment 2 ran from August 2011 for 10 weeks. In each experiment, Holstein-Friesian heifers were divided into three treatment groups (12 animals/group) consisting of calves, yearling heifers, and in-calf heifers (average ages: 8.5, 14.5, and 20.5 months, respectively). Methane emissions were estimated for each animal in the final week of each experiment using the sulfur hexafluoride tracer technique. Dry matter (DM) intake was estimated using the calculated metabolizable energy (ME) requirement divided by the ME concentration in the grazed grass. As expected, live weight increased with increasing animal age (P<0.001); however, there was no difference in live weight gain among the three groups in Experiment 1, although in Experiment 2, this variable decreased with increasing animal age (P<0.001). In Experiment 1, yearling heifers had the highest CH4 emissions (g·d−1) and in-calf heifers produced more than calves (P<0.001). When expressed as CH4 emissions per unit of live weight, DM intake, and gross energy (GE) intake, yearling heifers had higher emission rates than calves and in-calf heifers (P<0.001). However, the effects on CH4 emissions were different in Experiment 2, in which CH4 emissions (g·d−1) increased linearly with increasing animal age (P<0.001), although the difference between yearling and in-calf heifers was not significant. The CH4/live weight ratio was lower in in-calf heifers than in the other two groups (P<0.001), while CH4 energy output as a proportion of GE intake was lower in calves than in yearling and in-calf heifers (P<0.05). All data were then pooled and used to develop prediction equations for CH4 emissions. All relationships are significant (P<0.001), with R2 values ranging from 0.630 to 0.682. These models indicate that CH4 emissions could be increased by 0.252 g·d−1 with an increase of 1 kg live weight or by 14.9 g·d−1 with an increase of 1 kg·d−1 of DM intake; or, the CH4 energy output could be increased by 0.046 MJ·d−1 with an increase of 1 MJ·d−1 of GE intake. These results provide an alternative approach for estimating CH4 emissions from grazing dairy heifers when actual CH4 emission data are not available.
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