Maize feeding studies with town-supply cows

Abstract

Abstract Six vanetles of maize, differing in relative maturity rating, were compared to assess their dry-matter yield and nutritive status for feeding as silage or grain to winter-milking, town-supply cows in the southern areas of New Zealand. In a maximum period of 150 days the late-maturing hybrid (PX610) produced 29 tonnes dry matter per ha, a yield 30–70 percent higher than other varieties. The grain of early-maturing varieties appeared to have the capacity to ripen, PX442 yielding 15 tonnes dry matter per ha of ear weight. The latter was only little better than the annual production of irrigated pasture in this region. Early- and late-maturing varieties reached a total plant dry matter content of 30 percent (‘dent’) about 130 and 150 days after sowing respectively. At this stage the proportion of leaf and stem had decreased and the ear constituted 50–60 percent of the plant dry matter. The protcin, Ca, and P content of at least two hybrids (KC3 and PX610) was below the requirements of lactating cows, but the gross energy content of the total plant dry matter. when required for silage, was nonnal (4.3 Mcal/kg). It was concluded that high-yielding, late-maturing varieties of maize, with maturity ratings similar to hybrid PX610, should be used as maize silage for lactating cows in this region. To avoid loss of potential yield of dry matter, maize should not be taken for greenfeed if the economics of ensiling maize are favourable. Neither should maize be harvested for grain because of low yields of early-maturing varieties and the inability of late-maturing varieties to ripen.