Extensivation of roughage production and varying of concentrate supply: factors for feed intake, development of body weight and milk production in primiparous Black and White German Holstein cows

The effects of extensively produced roughages and reduced concentrate suppl y on intake and milk production was studied with 47 primiparous cows (Germa n Holsteins Black and White). The roughage mixture from silage and hay cont ained 5,2 MJ NEL compared to conventional feed with 5,6 MJ/kg dry matter. C oncentrates were offered according to milk production or at a level with 50 % reduction. This reduction was moderate in the first 2 months of lactation and more pronounced later on. At the beginning of lactation 6 kg of extens ively produced roughages were eaten compared to 7 kg with conventional feed . Roughage intake increased to 10 kg at the 50(th) day of lactation and to 12-14 kg at the end. Effects of roughage quality at these times of lactatio n were limited. Milk production declined with extensively produced roughage s and reduced concentrate supply more intensively than with conventionally produced roughages and normal concentrate supply. The optimal postpartal le vel of milk production in primiparous cows - most likely due to limited cap acity of digestion can only be stimulated by an optimal supply with suffici ent concentrates in the first period of lactation. A steady live weight gain in the first months after calving was observed on ly in cows receiving a high supply of concentrates and high quality roughag es. Weight gain in the other groups was limited so that they did not exceed their weight measured directly after calving prior to the day 100 of lacta tion. Lipid mobilization in the postpartal period, measured by the deuteriu m-dilution technique only moderately corresponded to weight loss. As a conclusion it can be stated, that cows in the first lactation with hig h yield capacity should be fed in the first third of lactation with optimal amounts of concentrates as their roughage intake capacity is still very li mited. At this stage of lactation, roughage quality (5,2 MJ NEL versus 5,6 per kg dry matter) seems to be of minor importance and the main role of rou ghage is to provide structural fibre.