The objective of this study was to investigate the effects of yeast culture (YC) on the growth performance, caecal microbial community and metabolic profile of broilers. A total of 350 1-day-old healthy Arbor Acres broilers were randomly assigned to seven treatment groups. The first group received a basal diet without YC supplementation, whereas the remaining groups received a basal diet supplemented with either YC fermented for 12, 24, 36, 48 or 60 hr, or a commercial YC product (SZ2). MiSeq 16S rRNA high-throughput sequencing was used to investigate the bacterial community structure, and gas chromatography-mass spectrometry was used to identify the metabolites in the caeca of broilers. The broilers that received a diet supplemented with YC had a higher average daily gain and average daily feed intake than those received YC-free or SZ2-enriched diets. The feed conversion ratio (FCR) of YCs fermented for 24 hr resulted in the best feed efficiency, whereas the FCR of YC fermented for 60 hr resulted in poor feed efficiency (p < .05). In the caeca of broilers, the bacterial communities were well separated, as determined by principal component analysis, and the proportions of the eight genera were significantly different among the seven groups (p < .05). The genus Akkermansia was the most abundant when the diet supplemented with YC fermented for 24 hr (p < .05). Furthermore, the Firmicutes/ Bacteroidetes ratio was positively correlated with the FCR in the caecum (r = .47, p < .005). Five differentially expressed metabolites (i.e., L-alanine, benzeneacetic acid, D-mannose, D-arabitol and cholesterol) were identified in the caeca of broilers that received diets supplemented with YCs fermented for 24 or 60 hr. In summary, the different fermentation times of the YCs can markedly improve the growth performance and FCR of broilers by altering the caecal microbial community, and the growth performance which is related to the changes in key metabolic pathways. K E Y W O R D Sbroilers, gas chromatography-mass spectrometry, growth performance, metabolite, microbiome | 213 SUN et al.

Background:In highly intensive dairy farms, cows often suffer from metabolic disorders that cause severe oxidative stress.Objectives: This study aimed to observe correlations and associations of oxidative stress-related indicators with milk compositions and metabolites.Methods: Twenty-two multiparous Holstein dairy cows in early lactation were randomly selected from a commercial dairy farm. The morning milk was collected for composition and metabolites analysis. Blood was sampled via the tail vein to analyze oxidative stress-related indicators (reactive oxygen species, ROS; catalase, CAT; superoxide dismutase, SOD; glutathione peroxidase, GPX; malondialdehyde, MDA) and metabolites.Results: Results showed that ROS were positively correlated with CAT, GPX, SOD, and MDA. However, the levels of CAT, GPX, and SOD were negatively related to milk fat (P < 0.05). Nineteen serum and 7 milk metabolites were selected from detectable metabolites according to their correlations with ROS, CAT, GPX, and SOD (P < 0.05). Metabolic pathway analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed that these metabolites are primarily involved in the metabolic pathways of carbohydrates and amino acids. Conclusions:This study gave us a better understanding on oxidative stress that ROS not only increased oxidative damage (MDA) in dairy cows, but also altered some metabolites involved in amino acid and carbohydrate metabolism.

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Infection with parasitic nematodes is a serious threat to health and production of small ruminant worldwide. It causes reduction in feed intake, weight gain and eventually death of the host. The primary control method of the nematode infection relied on frequent use of anthelmintic drugs. Unfortunately, this control strategy is no longer effective due to widespread anthelmintic resistance, which necessitates search for novel approaches to control nematodes. Condensed tannin (CT) containing forages have been used as anthelmintic to control parasitic nematodes for years. This paper reviews available information about effects of CT on productivity and health of small ruminants infected with parasitic nematodes. Many of temperate and tropical forages are nutraceutical plants (possess both nutritional and health benefits). Consumption of CT containing forages reduced negative impacts of gastrointestinal parasitism in sheep and goat by regulating establishment of worm as shown in reduced worm burdens, fecal egg count (FEC) and worm fecundity. Parasitized sheep and goats fed forages containing CT had high feed intake and body weight gain, probably due to increase in protein and amino acids supply. Condensed tannins containing feeds result in lighter meat color and tend to improve antioxidant activity. Therefore, the use of CT containing forages to control parasitic nematodes and improve production of small ruminants is one the alternatives to anthelmintic drugs.

Background Even if breed, parity, dietary and environmental management are same, dairy cows still have notable differences in milk yield that may be underpinned by physiologic differences. Objectives This study aimed to investigate the physiological dissimilarities of dairy cows with different milk yields. Methods Thirty cows were sorted into high milk‐yielding cows (group H: 58.93±2.31 kg/day), moderate milk‐yielding cows (group M: 44.99±0.54 kg/day), and low milk‐yielding cows (group L: 24.99±6.83 kg/day) according to milk yield. Blood was collected and serum parameters were assessed. Rumen fluid was collected for the evaluation of rumen fermentation parameters (RFPs) and bacterial community composition (BCC). Results Serum prolactin, growth hormone, glutathione peroxidase, immunoglobulin A and non‐esterified fatty acid had a significantly positive correlation with milk yield ( p < 0.05), whereas serum glucagon and total antioxidant capacity had a significantly negative correlation with milk yield ( p < 0.05). The concentration of valeric acid and the ratio of acetic acid to propionic acid in the rumen fluid in group H was significantly lower than that in group L ( p < 0.05). The concentration of acetic acid and butyric acid in group H was significantly lower than that in groups M and L ( p < 0.05). The relative abundances of Ruminococcaceae_NK4A214 _group, Prevotella_1 , Rikenellaceae_RC9_gut_group , Christensenellaceae_R‐7_group , Muribaculaceae , and Ruminococcus_2 were negatively correlated with milk yield, whereas the relative abundance of Succinivibrionaceae_UCG‐001 , Lachnospiraceae_NK3A20_group, Shuttleworthia and Dialister were positively correlated with milk yield ( p < 0.05). Conclusions This study indicates that dairy cows with different milk yields have clear divergence in serum indicators, RFPs, BCC and rumen microbial metabolism.

Processing can affect milk properties and alter the composition of milk metabolites, which has corresponding effects on milk flavor and quality. It is quite important to study the safe quality control of milk processing. Therefore, the purpose of this study was to identify metabolites at different steps of ultra‐high‐temperature‐sterilized (UHT) milk processing using gas chromatography–mass spectrometry (GC–MS). These steps included raw milk, pasteurized milk (80°C for 15 s), semi‐finished milk (after pasteurizing, it was homogenized at 75°C with pressure of 250 bar), UHT milk (at 140°C for 10 s), and finished milk (homogenized UHT milk). A total of 66 metabolites were identified across all samples, including 30 metabolites in the chloroform layers of the milk samples and 41 metabolites in the water layers; 5 metabolites were found in both layers. The metabolites were primarily fatty acids, amino acids, sugars, and organic acids. For example, pasteurized and ultra‐high‐temperature‐sterilized kinds of milk had lactose contents similar to those of raw milk, with increases in saturated fatty acids such as hexadecanoic acid and octadecanoic acid. Additionally, these findings indicated that these methods of processing can affect the contents of some components of milk. Therefore, from the perspective of milk's nutritional value and consumer health, the excessive heating of dairy products should be avoided and the milk heat treatment process should be standardized from the source.

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