Abstract
Simple SummaryThe development of rumen plays vital roles on the growth performance of calves. Rumen development is determined by rumen microorganisms, their metabolic products, and diet. Volatile fatty acids produced by ruminal microbes are one of the major determinants of ruminal papillary size and shape. Feed particle size could affect the development of rumen. Whether the roughage length determines the rumen development through the rumen microflora or not is worthy of investigation. The aim of this study was to investigate the comprehensive effects of roughage length and rumen bacterial community on the rumen development of weaned calves. Our results indicated that chopping roughage increased the ruminal bacteria involved in increasing the production of butyrate and promoted the process of bacterial colonization. This study illustrated chopping roughage at a short length could improve the rumen development and promote a stable rumen bacterial community of weaned calves.Roughage particle size can influence rumen development, which is also determined by rumen microorganisms and their metabolic end-products. Therefore, the aim of this study was to evaluate the comprehensive effects of roughage length and rumen bacterial community on the rumen development of weaned calves. A total of thirty-six weaned Angus female calves (125 ± 3 d; 161.2 ± 13.0 kg) were randomly assigned to three diets differing in roughage particle size: 4 cm (short length); 24 cm (medium length); and 44 cm (long length). Results showed that chopping roughage increased dry matter intake and organic matter apparent digestibility; altered rumen fermentation indicated by the increased rumen butyrate and valerate concentrations; and increased plasma glucose, cholesterol, and total protein. Chopping roughage affected rumen bacterial community, as indicated by altering the diversity indices; by increasing ruminal bacteria Papillibacter and Eubacterium_hallii_group, which are involved in butyrate production; and by increasing Synergistetes and Mogibacterium, which are involved in bacterial colonization. In conclusion, chopping roughage at 4 cm was shown to improve the rumen bacterial community, alter rumen fermentation, eventually promote the development of rumen.
Highlights
Beef calves are generally weaned by the abrupt separation of cows and calves, as well as changes in feed types and environment, which eventually cause weaning stress in calves [1]
Chopping roughage had no significant effects on the final body weight, average daily gain (ADG), and feed conversion ratio (FCR) of weaned calves (p > 0.05)
The Organic matter (OM) apparent digestibility was quadratically affected by chopping roughage
Summary
Beef calves are generally weaned by the abrupt separation of cows and calves, as well as changes in feed types and environment, which eventually cause weaning stress in calves [1]. Weaning stress plays vital roles in affecting the subsequent health and growth performance of calves. Young calves are usually fed with starter diets with high concentrate proportions in order to promote the development of rumen [3]. The fiber source is necessary for young calves due to its benefic functions, including stimulating rumination, expanding rumen volume, and reducing the keratinization of rumen papillae [4]. Pelleted starter diets with a low neutral detergent fiber (NDF) are often recommended for the preweaning calves, while the provision of roughage is urgent after weaning [6]. Chopping roughage length is generally considered to increase DMI owing to the shorter rumination time, faster passage rate in the rumen [7], and less wastage by avoiding selective consumption [8]. A fast passage rate in the rumen and shorter rumination time may result in reducing the ruminal pH due to limited buffer capacity [9]
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