Effects of feeding sugar beets, ensiled with or without an additive, on the performance of dairy cows

Abstract

Abstract The objective of this study was to examine the nutritional composition and quality of beet silages ensiled without (SBS–) and with silage additive (SBS+) and the effect on nutrient intake, milk yield, and milk composition when maize silage was replaced with SBS+ or SBS–. SBS– ferment heavily, and the main fermentation products are ethanol, lactic acid, and acetic acid. Adding a silage additive restricts fermentation and preserves most of the sugar in SBS+. Forty-two Holstein cows were used in a multiple 3 × 3 Latin square design. Each experimental period consisted of two weeks adaptation and one week of measurements. The cows were fed either a control diet (DCON) or diets where two-third of the maize silage was replaced with SBS+ (DSBS+) or SBS– (DSBS–) on a dry matter (DM) basis, in a partial mixed ration (PMR). The cows had access to one milking robot, and were offered up to 3.0 kg/day of concentrate in the milking robot. The concentrations of ethanol, lactic acid, acetic acid, and sucrose in SBS– were 90.7, 64.9, 29.9, and 1.4 g/kg DM, corrected for evaporation losses, respectively. The concentrations of ethanol, lactic acid, acetic acid, and sucrose in SBS+ were 4.4, 2.5, 4.4, and 105 g/kg DM, respectively. The intake of PMR did not differ between the three treatments. The intake of concentrate in the milking robot was lower for DSBS– and DSBS+ compared to DCON, due to fewer visits to the robot. Milk yield was lower but more concentrated for the two treatments with beet silages compared to DCON. The yield of energy corrected milk was 36.9 kg and 36.3 kg in DCON and DSBS–, respectively, which was higher than the 34.9 kg in DSBS+. It is concluded that the milk production value of SBS– is comparable to maize silage, whereas SBS+ seemed to be lower. However, this may be partly due to fewer visits to the milking robot and thus less concentrate intake in DSBS+. The results show that sugar beets ensiled wet, without silage additive, is a promising feed for lactating cows.