Latest News

• Add My News • Search Old News

Gippsland › Latest news › Department of Primary Industries

Crossbreeding Research Gathers Momentum

By Department of Primary Industry - 10th May 2005 - Back to News

The increased use of Holstein-Friesian cows in Victorian seasonally calving dairy systems has been associated with a decline in cow reproductive performance. Studies have shown that one way to improve cow reproductive performance in these systems is to use Holstein-Friesian x Jersey (HFJ) cross-bred cattle instead of purebred Holstein-Friesian (HF) cattle. This could be because HFJ cattle lose less body condition in early lactation than purebred HF cows, and at mating are in a more favourable condition to become pregnant. Despite this theory, there is little local data on liveweights and condition losses of HF and HFJ cows in pasture-based dairying systems.

The project utilised an existing study of the comparative reproductive performance and health of HF and HFJ cows, conducted by Dr Michael Pyman at Melbourne University.

Four herds were selected to study and all were:

• in Gippsland.
• Spring-calving HFJ and HF cows run under identical management conditions.
• participated in herd-testing.

DPI staff visited all herds on three occasions between calving and mating to gather information on condition score and liveweight. Herd test records were used to estimate milk and milksolids yield for each breed.

The results are presented in Table 1. On average, HF cows were 39 kg heavier than HFJ cows and produced 2.1 kg more milk. HF cows had lower concentrations of milk fat and protein, and differences in fat and protein yield between breeds were small. There was no difference in body condition score of HF and HFJ cows, nor in the amount of condition lost in early lactation.

Table 1. Milk production, liveweight and condition scores for Holstein-Friesian (HF) and Holstein-Friesian x Jersey cross cows (HFJ) on the four study farms¹.

¹Data are means for all cows on all farms. Full statistical analyses were conducted only for cows within each herd: this information is available in the project report to GippsDairy.

²Milk volume and composition parameters are daily means calculated from all available herd test data between calving and mating.

³CS data are averages from three tests between calving and mating.

This data does not support the theory that improvements in reproductive performance of HFJ crossbred cows compared to purebred HF cows are due to differences in body condition loss in early lactation. In fact body condition loss was low for all cows, probably because body condition at calving was also low. However, a full interpretation of the results of this study needs to be conducted in the context of whether or not reproductive differences did in fact exist between HF and HFJ cows in the study herds: these results will be available later in 2005.

This data will be used as background information to inform other future research projects.

CELERY GROWERS CHECK PROGRESS OF SEPTORIA LATE BLIGHT PROJECT

Late blight on celery is caused by the fungus Septoria apiicola. Septoria late blight can attack any part of the plant above ground. As outer leaves and stalk turn dark and wither, the entire field may look scorched. The disease develops and spreads during extended periods of leaf wetness and in particular with temperatures of 20-25°C. Celery is very susceptible to this disease, and as a result, growers are forced to make a number of fungicide applications during the growing season.

Internationally, there are concerns for the development of resistance by S. apiicola to currently used fungicides and for the potential environmental impact those fungicides may have. In Victoria, growers are keen to develop an understanding of this disease to explore the possibility of reducing the number of sprays used to control Septoria late blight.

Liz Minchinton, Savitri Nadesan and Slobodan Vujovic from DPI Knoxfield are currently working on a vegetable levy funded project to adapt a disease forecasting model called TomCast, to manage late blight (Septoria) in Australian celery. Tomcast is used in California and Mexico to time fungicide applications on celery so that sprays are only applied when conditions are conducive to the disease rather than on a routine weekly basis. In the US this has resulted in savings of one to three sprays per celery crop. A weather station in the crop records temperature and leaf wetness information that is fed into the TomCast model. When a designated threshold (disease severity value, ie DSV) is reached the grower is alerted to apply sprays.

Karl Reidel, a crop consultant also ran a trial at the DPI site to investigate the curative activity of a systemic fungicide (Difenicinazole) for Septoria late blight control. Difenicinazole appears to have efficacy as a curative for Septoria late blight. Chlorothanil, as expected, did not show curative activity and should be used as a preventative. However, researchers clarified that the results were not a spray recommendation.

For further information contact Liz Minchinton at DPI Knoxfield on (03) 9210 9222.

Source: http://gippsland.com/

Published by: news@gippsland.com