Supplementation of zero-grazed dairy cows with molassed sugar beet pulp, maize or a cereal-rich concentrate

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.