Effect of Replacing Maize Grain by Hybrid Rye Grain in the TMR on Performance of Mid-Lactating Dairy Cows

Grain from traditional varieties of rye is not commonly used in dairy cattle nutrition. However, new hybrid varieties of rye currently available are characterized by some nutritional and agrotechnical benefits. This paper deals with the hypothesis that rye grain derived from a hybrid variety may be an alternative for maize grain in diets for dairy cattle. Sixteen lactating Polish Holstein- Friesian cows were divided into two groups according to their parity (8 primi- and 8 multiparous), stage of lactation (106 ± 30 days after calving) and milk yield (34 ± 4 kg/day). Cows were fed a total mixed ration (TMR) containing grass silage and whole crop maize silage and 29.2% of the concentrate (in dry matter). The latter contained approximately 48% (as fed) of either maize grain (M) or hybrid rye grain (HR) as a main source of cereal grain. Experimental diets were fed for 9 weeks. The use of HR as a substitute for M did not affect (P>0.05) dry matter intake and milk yield. There were no differences between treatments in the content of milk solids, amino acids, and fatty acid profile. However, substituting M by HR positively influenced composition of milk protein fractions by increasing the proportion of α-casein (37.0 vs 39.7%; P<0.01) and к-casein (6.5 vs 7.3%; P=0.02) as well as decreasing the proportion of β-casein (28.8 vs 27.8%; P=0.02) and sensory characteristics of the milk (body and texture, and taste; P<0.05). In turn, the composition of the diet did not affect the technological suitability for processing of milk fat (acid and peroxide number, melting and solidification temperature), rennet coagulation time, heat stability or titratable acidity. This study has shown that hybrid rye grain may be an alternative for maize grain in a TMR based on grass and whole maize silage for mid-lactation dairy cows. Further studies are needed with higher proportion of hybrid rye grain in TMR or with other roughages used in a basal diet to fully determine efficiency of hybrid rye grain use in diets for dairy cows.