Veterinary Science - Theses
Permanent URI for this collection
Search Results
1 - 1 of 1
-
ItemA comparative study of the performance of New Zealand Friesian cross Holstein-Friesian cows in Victorian commercial dairy herds( 2011)This project combines the findings of two distinct research studies. The first being a comparative study involving nine commercial Victorian dairy herds, containing both New Zealand Friesian cross Holstein-Friesian (NZF×HF) and Holstein-Friesian (HF) cows. The second involved four farmer focus groups, collecting subjective information from three distinct groups of farmers on their breeding and semen selection decisions. The information gained in both parts of this study was designed to complement a previous crossbred study by Pyman (2007) and enable a holistic look at the use of a ‘different’ type of crossbred cow and whether this may be advantageous under typical Victorian, pasture based, seasonal calving conditions. The comparative field study collected data from nine Victorian herds over one single lactation. In total, 816 cows, including 529 Holstein-Friesians and 287 NZ Friesian×Holstein-Friesian cows were used to analyse reproductive performance and production based on a 305-day lactation. This enabled a comparison of breed differences to be assessed under pasture-based, seasonal calving conditions. The milk yield and reproductive performance parameters were adjusted for herd, age group, and interval from calving to mating start date. The Holstein-Friesians produced a higher volume of milk (203 litres, p=0.015) than the NZF×HF cows, but only after the exclusion of cows with lactations less than 250 days. The NZF×HF cows had higher concentrations of milk fat (0.17%, p≤0.0001) and protein (0.09-0.10%, p<0.001) than the HF cows, regardless of lactation length. Reproductive performance of the NZF×HF cows was superior to that of the HF cows in the nine herds with 14-week ICR (77.8 vs 69.0, p=0.027) and not in calf at 21 weeks (20.5 vs 29.8, p<0.019). Of the 23 farmers involved in the four focus groups, 13 were split calving, 9 were seasonal and 1 was calving year round. For the majority of the split calving herds and for the year round calving herd their current calving system “had chosen them”, rather than “them choosing the system”, as a result of their inability to get cows in calf. All crossbred and 5 of 9 LIC farmers included fertility in their breeding objectives, despite improvements over the last few years, while only 2 of 6 HF farmers included fertility, despite no farmers noting fertility improvements and inspite of the fact that half of these farmers were seasonally calving. In general, the farmers that had remained seasonal calvers, felt that this system was easier/simpler, provided a better lifestyle and was more cost effective, as they could rely more on seasonal pasture growth. All three groups of farmers wanted to breed cows that specifically fit their system, with an “ideal” cow being one “that you did not know was in the herd”. As a result, when selecting sires, all three groups of farmers were more concerned with non-production traits; including fertility, calving ease, temperament and udder, than production traits. Most farmers consulted bull catalogues, but relied on individual relationships to assist with breeding and sire selection. Farmers were generally happy with the sires available but all three groups felt that inbreeding was an issue, especially for the minor breed groups. Farmers that were crossbreeding seemed to use one of two broad systems to maintain their herd structure: 1) Non-Specific Crossing Structure: farmers used sires on an individual cow basis to maintain a cow’s size or to maintain a cow within the herd. 2) Specific Crossing Structure: farmers used sires (three or four way cross) in a predetermined order to maximise hybrid vigor. Overall the study was able to show that daughters of NZF sires, crossed with Victorian HF’s, were better able to get in calf and were less likely to be non-pregnant at the end of joining, than Victorian HF cows. Given that fertility was the main driver “forcing” farmers to adopt split calving systems and was also found to be far more important than production, in influencing farmer’s breeding objectives and semen selection decisions, it is likely that this crossbred may suit pasture-based, Victorian farmers, especially those wishing to maintain a 12 month calving interval.