Abstract
Supplementation plays a vital role in the growth performance of grazing heifers. We investigated the effects of maize-based concentrate supplementation on the serum metabolome in grazing heifers. Twenty-four 7-month-old heifers (211.65 ± 4.25 kg BW) were randomly divided into a supplement (SUP) group and a control (CON) group. The results indicated that concentrate supplementation increased the final body weight (BW) of grazing heifers, and the average daily gain (ADG) was 61.5% (P = 0.011) higher in the SUP group than in the CON group. Serum concentrations of total protein (TP), triglyceride (TG), and leptin were higher in the SUP group than in the CON group (p < 0.05). Supplementation increased serum metabolites and amino acids and markedly altered glucose, lipid, and protein metabolism, which contributed to the heifer growth. Furthermore, by multivariate analysis, 45 serum metabolites were identified as significantly different between the two groups. Enrichment analysis revealed that arginine biosynthesis and tryptophan metabolism as well as glycerophospholipid metabolism were significantly enriched between the two groups. We concluded that the growth potential of heifers could be improved by maize-based concentrate supplementation, and the main biological pathways affected were those related to energy and amino acid metabolism.
Highlights
Grazing is a very important production system for the ruminant industry worldwide due to its low cost and benefit to animal welfare [1]
The initial body weight (BW) did not differ between the SUP and CON groups, but after 60 days, a significant difference in the final BW (p < 0.05)
We found that the levels of numerous amino acids in serum were higher in the SUP group than in the CON group
Summary
Grazing is a very important production system for the ruminant industry worldwide due to its low cost and benefit to animal welfare [1]. A major challenge of this system is the imbalance between pasture availability and animal nutritional requirements [2]. Most beef cattle are grazed extensively on pasture without any feed supplements on the grasslands of Inner Mongolia in northern China, which results in decreased animal performance and low productivity [3]. Many researchers have revealed that the dry matter intake (DMI) and productivity of grazing ruminants during periods of pasture grazing or nutrient deficiencies could be improved by supplementation with protein [4], minerals [5], or multinutrient concentrates [6]. Pasture availability and nutritive value seem to be sufficient to meet the requirements for cattle grazing in summer. Supplementation could help alleviate the pressure of grassland degradation caused by overdependence on the grasslands of Inner Mongolia [9]
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