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Genetic and phenotypic parameters were estimated for production and disease traits (including dagginess) from about 2 million pedigree-recorded animals born between 1990 and 2008 in New Zealand dual-purpose ram breeding flocks. This is the most comprehensive study of genetic parameter estimates for the New Zealand sheep industry to date and includes estimates that have not previously been reported. Estimates of heritability were moderate for BW at 8 mo (LW8), fleece weight at 12 mo (FW12), dagginess score at 3 and 8 mo (DAG3, DAG8; 0.31 to 0.37), typical for weaning weight (WWT), fecal egg count in summer (FEC1) and autumn (FEC2), and analogous Nematodirus counts (NEM1, NEM2; 0.17 to 0.21), and low for number of lambs born to ewes (NLB; 0.09). The genetic correlations among production traits, WWT, LW8, and FW12, were positive and moderate to high. Correlations of DAG3 and DAG8 with production and disease traits were low and mostly negative. The NLB had low, but typically positive, correlations with other traits. Disease traits also had low, but positive, correlations with production traits (WWT, LW8, and FW12), and were highly correlated among themselves. In general, the heritability estimate for BW and dagginess were greater than what is currently used in the New Zealand genetic evaluation service (Sheep Improvement Limited), and the availability of accurate estimates for dagginess plus parasite resistance and their genetic correlations with production traits will enable more accurate breeding values to be estimated for New Zealand sheep.

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Breeding beef heifers for the first time at 15 months of age has potential to increase the efficiency of the beef breeding-cow herd. An increased incidence of dystocia in heifers calving at 2 years of age, compared to mature cows, is a major reason many farmers in New Zealand have not adopted the practice. The predominant type of dystocia affecting 2-year-old heifers is feto-maternal disproportion, a condition in which the fetus is too large relative to the size of the heifer's pelvis. Reducing birthweight of the calf is a means of reducing the incidence of dystocia. Birthweight and length of gestation are determined by genotype of the calf, maternal genetic effects and environmental effects. Bulls with low estimated breeding values for birthweight have been selected for mating heifers; however, the positive genetic correlation between birthweight and mature weight meant that the progeny of these bulls tended to be lighter at finishing, making them less desirable in the beef industry. The genotype of the dam also plays a role in determining the risk of dystocia; the maternal ability of the dam to nurture the fetus influences birthweight, and the dam's genetic potential for growth influences the size of her pelvic area. Heavy heifers tend to produce high birthweight calves, counteracting the reduction in the incidence of dystocia resulting from the larger pelvis in larger heifers. Manipulating feeding level during pregnancy offers an alternative method for manipulating the birthweight of calves. Little is known about the effects of nutrition in early gestation on placental development or birthweight of calves. No differences in the birthweight of calves have been observed in response to variation in feeding in mid-pregnancy, and variable responses in birthweight and the incidence of dystocia to feeding in the third trimester of pregnancy have been reported. Differences in birthweight have not always resulted in differences in the incidence of dystocia, primarily due to differences in liveweight of the heifer also induced by feeding regimens. Variability in the incidence of dystocia in response to feeding level in the third trimester of pregnancy makes it difficult to make recommendations for the feeding of heifers at this stage of gestation. More research is needed into the effects of nutrition in early gestation on fetal and placental development in cattle.

Endophytes of Lotium spp. were studied, with particular emphasis on those in annual and hybrid ryegrasses. A previously undescribed Acremonium-like species of endophyte has been isolated fr•om Lotium multijiorum, Lotium x hybridum cv. Grasslands Manawa, and six species and varieties of annual Lotium spp. This fungus has been cultured and successfully inoculated into seedlings of L. multijiorum. Mycelium occurs in nodes, leaf sheath bases, culms, and seeds of infected plants. It is common in most New Zealand cultivars and ecotypes of L. multijiorum but not in cultivars from overseas. Mycelium of a second endophyte, a Gtiocladiumlike sp., occurred in plants of L. multijiorum, L.x hybridum, and L. perenne, but mycelium of a third endophyte, A. lolii, was found only in L. perenne and L. x hybridum cv. Grasslands Ariki. Seedlings of L. multijiorum, L. temulentum, and 'Grasslands Manawa' were artificially infected with A. lolii. Mycelium of this fungus was not confined to the base of leaf sheaths of these plants but grew throughout the sheath.