Effects of type and treatment of grain and protein source on dairy cow performance

Abstract

The effects of different types of energy or protein supplementation on performance of cows given grass silage-based diets were studied. The possibility of maintaining high energy intakes by using different grain sources, barley or maize, or by the use of the physical processing of the barley was investigated. In addition, the relative quality of rapeseed meal as a protein supplement compared with alternative protein supplements was examined. In experiment 1 16 Finnish Holstein-Friesian cows were used in a cyclic change-over design experiment with eight diets and four 21- day periods. The concentrate supplements comprised a 2 ✕ 2 ✕ 2 factorial arrangement of two grain sources (barley (B) and maize (M)) given either ground (T–) or steam-rolled (T+), each supplemented with either rapeseed expeller (R) or a mixture of maize gluten and soya-bean meal (GS). Grass silage was given ad libitum and concentrates at a rate of 11·2 kg DM per day. M supplements increased milk, milk protein and lactose output (P < 0·05) and decreased milk urea concentration (P < 0·01) compared with B supplements. Blood β-hydroxy-butyrate (BHB) and plasma urea concentrations were higher (P < 0·01) for B than M diets. R supplements increased silage intake, energy-corrected milk yield and milk protein output and concentration (P < 0·05) compared with GS supplements. Steam-rolled grain decreased food intake, blood BHB (P < 0·05) and plasma and milk urea concentrations (P < 0·001). Steam rolling improved organic matter digestibility (grain ✕ processing interaction, P < 0·05) with M but not with B supplements.In experiment 2 four Finnish Holstein-Friesian cows fitted with rumen cannula were used in a balanced complete change-over design to evaluate ground or steam-rolled barley (T– v. T+) and two protein treatments (rapeseed expeller, R or a mixture of maize gluten/soya-bean meal/sugar beet solubles, GSS). Cows were given concentrates at 11·2 kg dry matter (DM) per day and offered grass silage ad libitum. There were no differences (P > 0·05) in food intake, digestibility or milk production and composition between treatments. Plasma urea concentrations (P < 0·01) and molar proportion of butyrate (P < 0·05) in rumen fluid were decreased with R compared with GSS supplements. The results showed that replacing B with M grain resulted in minor increases in milk production. Steam rolling of grain did not influence animal performance. Among the protein supplements R increased animal performance compared with GS supplement.

The effects of and interactions between the maturity of grass silage and concentrate starch source when offered as total mixed rations on the performance of dairy cows

“…Concentrate starch source The lack of effects from replacing barley-with maize-based concentrate on cows' DMI were consistent with the findings of Khalili et al (2001) but not with those of others (McCarthy et al, 1989;Overton et al, 1995;Silveira et al, 2007), who observed a reduction in the DMI of cows on barley-based diets. The diets and other experimental conditions used in the study reported herein differed from those in which feeding with barley-based concentrates resulted in DMI reduction but similar to those of Khalili et al (2001).…”

“…We were unable to explain the observed greater NDFD in B diets in our study, thereby speculating that increased iNDF levels in M diets may be responsible. A similar observation regarding the effect of increased proportional contribution of concentrate NDF on the total NDFD has been made by Khalili et al (2001).…”

“…In some cases, maize supplements have been found to increase MY relative to that observed with barley (McCarthy et al, 1989;Overton et al, 1995;Khalili et al, 2001); however, this effect is not always observed (DePeters and Taylor, 1985;Grings et al, 1992;Yang et al, 1997). In our experiment, the yield of milk constituents was also not affected by the type of the concentrate starch, probably because of the absence of differences in MY.…”

“…The values of DMD and OMD were not statistically different for the two concentrate starch sources; these findings agree with those of DePeters and Taylor (1985), who observed no differences in total tract diet digestibility when maize replaced barley in the diets. It has previously been reported that total NDFD was greater for maize compared with barley supplements (McCarthy et al, 1989;Khalili et al, 2001). We were unable to explain the observed greater NDFD in B diets in our study, thereby speculating that increased iNDF levels in M diets may be responsible.…”

“…The diets and other experimental conditions used in the study reported herein differed from those in which feeding with barley-based concentrates resulted in DMI reduction but similar to those of Khalili et al (2001). However, both groups of studies were focused on examining the effects of varying the type of the concentrate starch source.…”