Abstract
We examined the effects of substituting soybean meal with either yeast protein from Cyberlindnera jadinii or barley in concentrate feeds on feed intake, ruminal fermentation products, milk production, and milk composition in Norwegian Red (NRF) dairy cows. The concentrate feeds were prepared in pellet form as soy-based (SBM; where soybean meal is included as a protein ingredient), yeast-based (YEA; soybean meal replaced with yeast protein), or barley-based (BAR; soybean meal replaced with barley). The SBM contained 7.0% soybean meal on a dry matter (DM) basis. This was replaced with yeast protein and barley in the YEA and BAR concentrate feeds, respectively. A total of 48 early- to mid-lactation [days in milk ± standard deviation (SD): 103 ± 33.5 d] NRF cows in their first to fourth parity and with initial milk yield of 32.6 kg (SD = 7.7) were allocated into 3 groups, using a randomized block design, after feeding a common diet [SBM and good-quality grass silage: crude protein (CP) and neutral detergent fiber (NDF) content of 181 and 532 g/kg of DM, respectively] for 14 d (i.e., covariate period). The groups (n = 16) were then fed one of the dietary treatments (SBM, YEA, or BAR) for a period of 56 d (i.e., experimental period). The concentrate feeds were offered in split portions from 3 automatic feeders using electronic identification, with ad libitum access to the same grass silage. Dietary treatments had no effect on daily silage intake, total DM intake, or total NDF intake. Dietary CP intake was lower and starch intake was higher in the BAR group compared with the other groups. Ruminal fluid pH, short-chain volatile fatty acid (VFA) concentrations, acetate-to-propionate ratio, and non-glucogenic to glucogenic VFA ratio were not affected by dietary treatments. No effects of the dietary treatments were observed on body weight change, body condition score change, milk yield, energy-corrected milk yield, milk lactose and fat percentages, or their yields. In conclusion, yeast protein can substitute conventional soybean meal in dairy cow diets without adverse effect on milk production and milk composition, given free access to good-quality grass silage.
Highlights
Sustainable meat and milk production is essential for future agricultural production
Diets for high-yielding dairy cows in the Nordic countries commonly consist of grass silage (Huhtanen et al, 2013) augmented with concentrate feeds based on barley and a relatively high proportion of imported protein feed ingredients such as soybean meal, corn gluten meal, and rapeseed meal (Åby et al, 2014)
The main objective of this study was, to evaluate the effects of total substitution of soybean meal in concentrate feeds by C. jadinii yeast protein in grass silage-based rations of early- to mid-lactation NRF cows on feed intake, ruminal fermentation parameters, milk yield, and milk composition
Summary
Sustainable meat and milk production is essential for future agricultural production. Diets for high-yielding dairy cows in the Nordic countries commonly consist of grass silage (Huhtanen et al, 2013) augmented with concentrate feeds based on barley and a relatively high proportion of imported protein feed ingredients such as soybean meal, corn gluten meal, and rapeseed meal (Åby et al, 2014). A growing need exists to develop novel, sustainable, nonfood protein sources that can be used in animal diets to allocate food protein to the increasing human population. In Norway and elsewhere, have focused on the effects of partial or complete substitution of imported protein ingredients with alternative protein sources in animal feeds (Neal et al, 2014; Dalle Zotte et al, 2019; Cruz et al, 2020a,b). With a forest cover of about 38% of the total land area
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