Holstein dairy cows with high phosphorus utilization efficiency fed a low phosphorous diet secreted less phosphorus with urine but more with milk and feces

Metabolomics and amino acid profiling of plasma reveals the metabolite profiles associated with nitrogen utilisation efficiency in primiparous dairy cows

Nitrogen (N) utilisation efficiency (NUE, milk N yield [g/d]/N intake [g/d]) is an important performance indicator in dairy farming. Determining the NUE-associated blood metabolite profile will contribute to the optimisation of nutritional strategies to further improve NUE among dairy cows. Here, 20 primiparous lactating cows with days in milk ranging from 95 to 115 days were selected from a total of 1 221 cows. Each cow's N intake and milk N yield were measured for 7 days. Subsequently, blood samples were collected before morning feeding. Based on analysis and calculations, cows were retrospectively classified into two groups based on their NUE values, namely, a low NUE group (LNUE, NUE = 24.8 ± 1.6%, n = 10, mean ± SD) and a high NUE group (HNUE, NUE = 35.2 ± 1.7%, n = 10, mean ± SD). Plasma samples were selected from six cows in each group for metabolomics and amino acid profiling. Among the 41 differential metabolites (DMs) identified in the metabolomic analysis, sucrose, MG(0:0/22:1(13Z)/0:0), 2-amino-6-hydroxyhexanoic acid, and L-glutamine exhibited significant correlations with NUE, milk yield, and BW (P < 0.05). Moreover, the five differential amino acids and amino acid metabolites (DAAs) identified in the amino acid profiling and 5 of the 6 differential amino acids and amino acid conjugates identified by plasma metabolomics were found to be less abundant in the HNUE group (P < 0.05). Specifically, there was a 39.4% decrease in L-arginine content and a 29.2% decrease in L-glutamine content (P < 0.05). Pathway analysis indicated that the DMs and DAAs were mainly involved in arginine biosynthesis, glutathione metabolism, arginine and proline metabolism, and tryptophan metabolism (pathway impact > 0.1). These results provided new insights into the new blood metabolite profile associated with NUE in dairy cows. These new insights can provide foundational information for the formulation of new strategies to further enhance NUE in dairy cows.

Growth Performance, Bone Development and Phosphorus Metabolism in Chicks Fed Diets Supplemented with Phytase Are Associated with Alterations in Gut Microbiota

Phosphorus pollution caused by animal husbandry is becoming increasingly problematic, especially where decreasing and non-renewable phosphorus resources are concerned. We investigated the growth performance, bone development, phosphorus metabolism and gut microbiota changes elicited by different phosphorus levels with/without phytase in chicks during the brooding period (1-42 d). Five-hundred-and-forty (540) egg-laying chickens were assigned to six groups (0.13% NPP, 0.29% NPP, 0.45% NPP, 0.13% NPP + P, 0.29% NPP + P and 0.45% NPP + P) according to a factorial design with three non-phytate phosphorus (NPP) levels (0.13, 0.29 and 0.45%) and two phytase (P) dosages (0 and 200 FTU/kg). Chicks fed with the diet with 0.13% NPP had the lowest body weight, average daily gain, shank length, average daily feed intake and highest ratio of feed to gain, while phytase supplementation was able to mitigate the adverse effects of low-phosphorus diets on growth performance. Moreover, phosphorus metabolism was affected by different dietary NPP and phytase levels. Thus, 0.13% NPP significantly reduced serum phosphorus, while phytase supplementation significantly increased serum phosphorus. Notably, phosphorus utilization in the 0.13% NPP group was significantly decreased and the phosphorus excretion ratio was increased. Phytase supplementation significantly improved phosphorus utilization by 43.79% and decreased phosphorus emission in the 0.13% NPP group but not in the 0.29% NPP or the 0.45% NPP group. Remarkably, the alpha diversity of gut microbiota was significantly decreased in the low-phosphorus group, while phytase supplementation increased alpha diversity and improved gut microbial community and function. The LEfSe analysis revealed that several differential genera (e.g., Bacteroides, norank_f__Clostridiales_vadinBB60_group and Eggerthella) were enriched in the different dietary NPP and phytase levels. Furthermore, correlations between differential genera and several crucial phenotypes suggested that the enrichment of beneficial bacteria with different levels of phosphorus and phytase promoted phosphorus utilization in the foregut and hindgut. In summary, low-phosphorus diets inhibited growth performance and bone development, decreased utilization of phosphorus and altered gut microbial structure and function in the brooding stage of chicks. Finally, phytase supplementation improves growth performance and bone development and decreases phosphorus emission, and the potential mechanisms may be associated with the reprogramming of gut microbiota.

Use of fat-soluble vitamins and feed additives in cow diets

The authors have created modern effective methods for controlling the vitamin content of highly productive lactating cows during the first period of lactation. The results were obtained on the content of vitamins in the diet, milk and blood when feeding with supplements Vitaminol and phytocomplex at 10, 15 and 20 g per animal unit daily separately and with mixed feed. The authors monitored the levels of vitamins A, carotene, D and E in cow's milk and serum. Scientific research was carried out for the agricultural enterprise "Novgorodsky Becon" of the Novgorod region. The cows ration was balanced by 50 nutrients and biologically active substances in accordance with the recommendations for animal feeding (Moscow, Russian Academy of Agricultural Sciences, 2003). Studies of the content of vitamins were carried out using the silage-concentration type of ration fed to lactating black-and-white cows in conditions without grazing. We conducted 2 scientific experiments and 2 physiological experiments with cows during the first 100 days of their lactation. The increase in the level of vitamin A in milk and blood was due to the use of feed additives in the diets. The use of feed additives increased the vitamin D levels in milk and serum. The balance of calcium and phosphorus metabolism in cows is positive. The use of "Vitaminol" together with compound feeds increased the level of calcium by 5.6 6.3 and phosphorus by 4.4 4.9 grams per 1 kg of milk with the natural fat content. The diets were admixed with the "Vitaminol" and phytocomplex ratio of Ca: P (1.3: 1) and Na: K (0.2: 1). With the same doses of feed additives, the ratio of acid and alkaline elements in the diets was the same: Vitaminol was 0.743 and phytocomplex was 0.709. Due to the use of "Vitaminol", the concentration of vitamin E in milk is 4.6-6 times higher than that in the control group, in blood and blood serum.