Abstract
Simple SummaryThe usage of alfalfa (Medicago sativa L.) as a dietary protein source for ruminants in China is limited by forage quality and planting scale. Paper mulberry (Broussonetia papyrifera L., RY) has emerged as a new and representative high-protein woody forage resource for ruminants. However, information is less available regarding how substituting RY for alfalfa affect the fermentation and protein quality in total mixed ration (TMR) silages. This study evaluated ensiling characteristics, protein quality, and in vitro digestibility in TMR silages by mixing RY with alfalfa at different rations. The TMR were made with alfalfa and RY mixtures (36.0%), maize meal (35.0%), oat grass (10.0%), soybean meal (7.5%), brewers’ grain (5.0%), wheat bran (5.0%), premix (1.0%), and salt (0.5%) on a dry matter basis, respectively. The alfalfa and RY mixtures were made in the following ratios of dry matter: 36:0 (RY0), 27:9 (RY9), 18:18 (RY18), 9:27 (RY27), and 0:36 (RY36). The results showed that RY substitution had no adverse effect on fermentation quality and nutritional composition, but inhibited true protein degradation, while decreasing in vitro dry matter and crude protein digestibility. Therefore, RY and alfalfa mixtures at a ratio of 18:18 is suitable for silage-based TMR.To develop an alternative high-protein forage resource to alleviate ruminant feed shortages, we investigated the effects of replacing alfalfa (Medicago sativa L.) with different ratios of paper mulberry (Broussonetia papyrifera L., RY) on fermentation quality, protein degradation, and in vitro digestibility of total mixed ration (TMR) silage. The TMR were made with alfalfa and RY mixtures (36.0%), maize meal (35.0%), oat grass (10.0%), soybean meal (7.5%), brewers’ grain (5.0%), wheat bran (5.0%), premix (1.0%), and salt (0.5%) on a dry matter basis, respectively. The alfalfa and RY mixtures were made in the following ratios of dry matter: 36:0 (RY0), 27:9 (RY9), 18:18 (RY18), 9:27 (RY27), and 0:36 (RY36). After ensiling for 7, 14, 28, and 56 days, fermentation quality, protein degradation, and microbial counts were examined, and chemical composition and in vitro digestibility were analyzed after 56 days of ensiling. All TMR silages, irrespective of the substitution level of RY, were well preserved with low pH and ammonia nitrogen content, high lactic acid content, and undetectable butyric acid. After ensiling, the condensed tannin content for RY18 silages was higher than the control, but non-protein nitrogen, peptide nitrogen, and free amino acid nitrogen contents was lower, while the fraction B1 (buffer-soluble protein) was not different among all the silages. Dry matter and crude protein digestibility for RY27 and RY36 silages was lower than the control, but there was no difference between control and RY18 silages. This study suggested that ensiling RY with alfalfa inhibited true protein degradation, but decreased in vitro dry matter and crude protein digestibility of TMR silages, and that 18:18 is the optimal ratio.
Highlights
Alfalfa (Medicago sativa L.) is commonly used as an excellent high-protein forage for dairy cows, but the availability in China is limited by forage quality and planting scale
The purpose of this study was to evaluate the effects of substituting different levels of RY for alfalfa on the fermentation quality, chemical composition, protein degradation, and in vitro digestibility of total mixed ration (TMR) silages
This study indicates that the addition of 18% RY was the most optimal for formulating TMR silage because of the balance of fermentation quality, feed-nutritional value, protein degradation, and in vitro digestibility
Summary
Alfalfa (Medicago sativa L.) is commonly used as an excellent high-protein forage for dairy cows, but the availability in China is limited by forage quality and planting scale. As one of China’s top ten targeted poverty alleviation projects, over 300,000 hectares of RY are cultivated in China [3]. It is rich in crude protein (CP) and contains highly digestible fiber and minerals [2]. Multiple biologically active ingredients are associated with its antioxidant and anti-inflammatory functions in ruminants [3,4]. These merits make it attractive to exhibit great potential and applicability as a nutrient-enriched forage resource for local animal production
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