Effects of grass clover-pellets and whole plant maize-pellets on the feed intake and performance of dairy cows

Twenty dual-purpose Simmental dairy cows were used in a 2 × 2 cross-over design to evaluate the effects of feeding, both pelleted vs. ensiled grass clover and whole plant maize on feed intake, milk production and composition, as well as on blood metabolites and some parameters of rumen fermentation. In addition to the pelleted/ensiled forages, all animals were offered grass hay, and, based on the individual milk performance prior to the beginning of the experiment, 1 kg of concentrate for every 2.35 kg energy-corrected milk (ECM) exceeding a daily production of 15 kg ECM. In both groups, the forage was offered so that grass hay, grass clover silage or pellets and whole plant maize silage or pellets would contribute 100, 450 and 450 g kg−1 to total forage dry matter intake (DMI), respectively. Both the treatment periods lasted for seven weeks. Average daily forage DMI was increased from 12.8 up to 18.6 kg when grass clover and whole plant maize were fed in the pelleted form. ECM production was elevated from 18.3 up to 20.3 kg (p < 0.001). Also, a significant increase was observed for milk protein and lactose level, while content of milk fat and concentration of milk urea were reduced. Rumen pH-values were significantly lower in the pellet-fed cows than in the silage-fed cows. The acetate to propionate ratio was narrowed down from 3.80 : 1 to 3.54 : 1. Concentration of blood serum urea was significantly reduced (0.8 mmol l−1) when pellets were fed. Except for glutamate dehydrogenase (GlDH), all the liver specific enzymes were within normal ranges. The analysis of glucose, protein and ketone bodies in the urine was negative for both the dietary treatments. Pelleted grass clover and whole plant maize proved to be superior to their ensiled counterparts in regard to DMI and milk performance, without having a negative impact on the health status of the animals, but extra milk output in relation to the additional feed intake was very low.