The effects of concentrate supplements on the performance of dairy cows offered grass silage ad libitum

Abstract

Ninety-six lactating British Friesian cows were offered ad libitum two grass silages having the following analyses: 181 and 241 g dry matter per kg fresh weight, 108 and 96g digestible crude protein per kg dry matter and 617 and 619 g digestible organic matter per kg dry matter. In addition, four concentrate supplements were offered, containing either 360 g crude protein per kg on an air-dry basis and given at the rate of 015 kg/kg milk or 180 g crude protein per kg given at the rate of 030, 0375 and 0·45 kg/kg milk. Large and highly significant differences were recorded in silage intake, mil yield, milk composition, live weight and condition score during the winter feeding period. These differences in performance were associated more with differences in energy than in protein intake. During the post-experimental grazing period no significant differences between treatments were recorded in milk yield and composition, with the exception of fat concentration, and by midsummer no significant differences were apparent in live weight. The results of the experiment were appraised in economic terms and implications for commercial practice discussed.

White or red clover-grass silage in organic dairy milk production: Grassland productivity and milk production responses with different levels of concentrate

“…However, this effect is sometimes observed in early lactation, as in the current experiment, and is likely due to low energy status in cows on a pure forage diet (Laird et al, 1981;Aston et al, 1995). The unsupplemented cows lost weight and were in negative energy balance (Table 7).…”

Supplementary feeding of forage to grazing dairy cows

“…Schmidt and Van Vleck (1974), that the lactose content of the milk is unaltered by the feeding regime, several experiments have shown a positive correlation between the level ofenergy intake and the milk lactose content (e.g. Rook and Storry, 1964;Laird et at., 1981).…”

A note on the potential conjoint use of body condition scores and milk protein concentrations as an index of dietary adequacy in lactating dairy cows

“…In the data from our field trial and in those reported by Laird et al (1981) and Moisey and Leaver (1985) the coefficients for the dependent variable (MP) in regressions (1) and (4) were 4-11 and 4-38 respectively. When these are rounded up to 4-0 it can be assumed that if deviations of MP from the supposed norm of 0-31 are reduced by a factor of 0-25, MP will have equal weighting with BCS.…”

“…It is calculated that in the experiment of Laird et al (1981) the range was -14-5 to +5-0 and in that of, Moisey and Leaver (1985) with higher milk yields and fixed levels of feeding ('flat-rate feeding') the range was +5-5 to +12-5. It is calculated that in the experiment of Laird et al (1981) the range was -14-5 to +5-0 and in that of, Moisey and Leaver (1985) with higher milk yields and fixed levels of feeding ('flat-rate feeding') the range was +5-5 to +12-5.…”

“…From published results of feeding trials with varying levels of concentrates fed, according to level of production, with silage (Laird, Leaver, Moisey and Castle, 1981) and using fixed levels of concentrates (Moisey and Lever, 1985) we calculated that: MP = 19-1 + 0-0703MI BCS = -0-544 + 0-0150MI MP = 21-6 + 4-38BCS…”