Aust. J. Exo. Awic.. 1987. 27. 41-4 4 1 Effects on milk production of feeding wheat supplements to grazing dairy cows in early lactation R. C. DobosA, W J. FulkersonA and P. J. MichellB *Tasmanian Department of Agriculture, Elliott Research Station, Private Bag 20, Burnie, Tas. 7320, Australia. BTasmanian Department of Agriculture, Mt Pleasant Laboratories, P.O. Box 46, South Launceston, Tas. 7250, Australia. Summary. Two herds, each of 19 Friesian cows, were run on separate farmlets in north-western Tasmania. One herd (NW) grazed pasture only, and was estimated to be receiving 75% of potential intake, while the second herd (W) received 3.0 kg coarsely hammer- milled wheat per cow, daily for 42 days during early lactation in addition to pasture. Although the feeding of wheat increased total feed intake, there was no significant difference between the groups in either daily milk yield (21.5~. 2 1.8 L cow-'), milk fat yield (1.1 v. 1.09 kg cow-'), liveweight change (0.05 v. -0.2 kg cow-l) and herbage intake (12.0 v. 12.0 kg DM cow-' day-') of cows or of pre- (1.77 v. 1.8 t DM ha-') and post- (1.31 v. 1.32 t DM ha-') grazing mass, on farmlets NW and W respectively. We conclude that the feeding of wheat did not increase milk production or improve liveweight change under the conditions of this experiment. Introduction Dairy farmers often use concentrates to alleviate seasonal feed deficits which cannot be met by homegrown con- served fodder. Feeding high energy supplements to cows under these circumstances may be efficient because the supplements seldom completely substitute for herbage and so total nutrient intake and consequently milk yield increase (Blaxter and Wilson 1963). Furthermore, any substitution may spare herbage for later use. This experiment studied the effect of feeding hammermilled wheat to cows in early lactation on immediate and total lactational production and on herbage production. Materials and methods The experiment was carried out from 23 August until 30 November 1984, at Elliott Research Station, in north- western Tasmania. Two 13.0-ha farmlets were split into 20 blocks (each 0.65 ha), with blocks between farmlets being matched for soil fertility, herbage composition, herbage growth (over the previous 12 months), soil type and topography. Herbage consisted of 70% ryegrass (Lolium perenne) and 30% white clover (Trifolium repens). Ilcrds Two herds, each comprising 19 Friesian milkingcows plus five ycarling heifers, were grazed on each farmlet, giving an cKcctivc stocking rate of 1.65 milking cow equivalents per ha. This is about 20n/0 above the average stocking rate for the district. The cows in each herd were matched for parity, previous milk fat production (1983-84 lactation), condition score (Earle 1976), liveweight in the week prior to the first expected calving date and expected and actual calving dates (see Table 1). Two cows in each herd were induced to calve prematurely (with subcutaneous injec- tion of 20 mg Opticortinol). Experimental design Herd W was fed 1.5 kg cow-' of coarsely hammermilled wheat at each ofthe 2 daily milkings, from 23 August until 3 October (feeding period). Grain on offer to each cow was Table 1. Mean & s.e. milk fat production in previous lactation (1983-84), condition score, liveweight in the week prior to expected start of calving, date of expected start of calving, and actual calving pattern for both herds for herd W and NW Herd: W NW Milk fat (kg) (1983-84) 163.1 i 7.1 173.3 i 5.8 Condition score 5.4 + 0.09 5.4 + 0.07 Liveweight (kg) 490 k 15.6 494 i 16.2 Expected start of calving 3 Aug. 1984 4 Aug. 1984 Actual calving pattern, days to: 50% of herd calved 15 19 75% of herd calved 26 28 100%of herd calved 43 36