Abstract
Experiments were carried out to investigate the effects of different carbohydrate sources on food intake, milk yield, composition of the milk and its urea content. The experimental design was a complete randomised block with four treatments per block. The treatments were: herbage only (OS), herbage plus molassed sugar beet pulp (MSB), herbage plus maize (M) and herbage plus a mixture of oats, wheat and soybean meal (CON). The experiments were carried out on three replicates (E1, E2, E3) with 20, 24 and 24 pure and cross-bred cows (Simmental, Simmental × Red Holstein Friesian). All cows were offered freshly cut herbage ad libitum. Each experiment lasted 10 weeks, including a preliminary period of 2 weeks. Supplements were fed per block on an equal energy basis for daily milk yields of 13–25 kg. Cows with a daily milk yield exceeding 25 kg received an additional supplement according to milk production and treatment (MSB, M and CON). Average (E1 to E3) total daily dry matter (DM) intakes were 15.0, 17.8, 17.6 and 17.4 kg DM for Treatments OS, MSB, M and CON, respectively. Only the total DM intake between Treatment OS and the other treatments differed significantly ( P < 0.05). Herbage DM intakes were in general highest for cows on OS (14.9 kg DM), with cows on MSB, M and CON consuming on average (E1 to E3) 12.1, 12.6 and 11.8 kg herbage DM day −1. The average daily milk yield (E1 to E3) was 18.6, 20.8, 22.4, and 22.9 kg for OS to CON with only the difference between Treatments M and CON being non-significant ( P > 0.05). The treatments had no significant effect on milk fat and protein contents. The supplementation of herbage with maize (M) or a mixture of cereals (CON) increased the lactose content compared with Treatments MSB ( P < 0.05 only in E1) and OS ( P < 0.05 only in E2). The highest intake of crude protein (CON) resulted in a significantly higher urea content of the milk compared with Treatments MSB and M.
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