Benchmarking fertility performance

Transcription

1 Vet Times The website for the veterinary profession Benchmarking fertility performance Author : David Mackey Categories : Vets Date : December 8, 2008 David Mackey describes an online resource that enables dairy farmers to access valuable comparative data about herd fertility and its financial impacts. POOR fertility performance is a widespread problem in dairy herds throughout the world. The situation in Northern Ireland is no different, with an average calving interval of more than 400 days and a cull rate in dairy cows of 7.5 per cent due to infertility (Mayne et al, 2002). This affects labour inputs, as a result of more prolonged calving patterns and the overall financial performance of the herd. Dairy farmers in Northern Ireland can now benchmark the performance of their herd with others by using Fertility Benchmarking Online (FBO). This internet-based facility was developed jointly by the College of Agriculture, Food and Rural Enterprise (CAFRE) and the Agri-Food and Biosciences Institute (AFBI) see Figure 1. FBO enables dairy farmers in Northern Ireland to benchmark heat detection efficiency, conception rates and overall fertility performance, as well as the financial cost of infertility in their herds. It can be accessed at Information needed to benchmark herd fertility To begin benchmarking, farmers need to input basic details about their herd, including: breeding start date; 1 / 10

2 voluntary waiting period; average milk yield (litres/cow/year); and average concentrate input (kilogram/cow/year). Herd records (including calving and service dates, and pregnancy diagnoses) are keyed in manually online, or they can be uploaded electronically using Farmwizard, Kingswood, Sum- IT/Agridata or United Milk Records. The type of calving pattern (autumn, spring or spread) is determined by the annual distribution of calvings ( Figure 2 ), and the breeding start date can be adjusted to suit each individual herd. While FBO was developed to suit all types of calving patterns, the benchmarking year begins on August 1 to suit the majority of dairy herds in Northern Ireland that calve eight to 10 months of the year, from autumn to spring. The breeding records grid lists up to five services per cow. Cows identified at calving as not intended for rebreeding, or those subsequently culled or sold for reasons other than infertility, can be removed by unticking the RB column ( Figure 3 ) so they are not included in the calculations for the herd. What does fertility benchmarking tell you? Two reports are available to assess a herd s fertility performance. The interim report is available throughout the breeding season and uses submission rate to assess heat detection accuracy, and 60-day non-return rate to assess conception rate. This gives farmers timely information on which to base management decisions while the breeding season is still in progress. The annual report available at the end of the breeding season, when the final pregnancy diagnosis has been conducted, provides a more comprehensive report outlining the following: Heat detection efficiency Submission rate. This is the main method of assessing heat detection efficiency and is the proportion of eligible cows served in a series of successive three-week periods, based on individual herd voluntary waiting period and breeding start date. Heat detection rate. This is based on the proportion of repeat services detected in the day period, over those in the 18-24, and day periods assuming zero, one or two missed heats (Gaines et al, 1993). Heat detection accuracy. This looks at interservice intervals and compares the distribution in 2 / 10

3 the zero to 17, 18-24, 25-35, and more than 48 against previously defined targets (Sreenan and Diskin, 1992), where the target proportion of repeats in the day period is 60 per cent. Conception rate. This indicates the rate to first, second or a combination of all services. Overall fertility performance Projected calving index. This is based on the last recorded service for each cow and a 280-day gestation length. Proportion of cows not in calf. This describes the proportion of cows intended for rebreeding that were not identified as pregnant at the end of the breeding season. Hundred-day in-calf rate. This is the proportion of cows intended for rebreeding that were back in calf again within 100 days of calving (Morton, 2001). Estimated cost of infertility. Based on projected calving index and the proportion of cows not in calf at the end of the breeding season (Esslemont et al, 2001). Cows with a prolonged calving interval have extended lactations and would have had a higher annual yield if they calved again sooner. There is also a considerable cost associated with replacing cows that are not in calf at the end of the breeding season. Results CAFRE published the first FBO results in early 2007, based on the performance of 90 herds in Northern Ireland for the breeding season ( Table 1 ). These herds represented a range of production systems, with 11 autumn, 12 spring and 67 spread calving herds, with annual yields of 4,600 to 10,700 litres/cow. The first-service submission rate averaged 60 per cent across the 90 benchmarked herds, but ranged from per cent between the bottom and top 25 per cent of herds. The average heat detection rate was 70 per cent, with a range of per cent in the bottom and top 25 per cent of herds. The highest submission and heat detection rates occurred in autumn and spring calving herds, which recorded submission rates of more than 70 per cent demonstrating a strong focus on heat detection for a short period of time. This is probably made easier through more cow-to-cow interaction, with more cows being on heat at one time, unlike spread calving pattern herds with an average submission rate of 57 per cent. Heat detection efficiency was also better in loweryielding and smaller herds. Across all 90 herds, the average conception rate to first service, based on pregnancy diagnosis, 3 / 10

4 was 53 per cent. This is higher than the 40 per cent average reported by AFBI Hillsborough, where conception rates were calculated following subsequent calving (Mayne et al, 2003). However, the aim of FBO is to provide timely feedback to farmers on herd fertility performance at the end of the breeding season. This will result in higher conception rate figures than those calculated following subsequent calving. Conception rates to first service ranged from per cent between the bottom and top 25 per cent of herds. These were higher in spring calving (60 per cent) than in autumn or spread calving herds (52 per cent), possibly as a result of lower yields, less nutritional stress and inadvertent selection of cows with better fertility, while infertile cows were culled. When herds were ranked according to yield, the top 25 per cent of herds (average yield 8,700 litres) had lower conception rates (46 per cent) than the remaining 75 per cent of herds. Similarly, herd size had a negative effect on conception rate, with the largest 25 per cent of herds (more than 120 cows) having an average rate of 44 per cent. Overall fertility performance Assessment of overall fertility performance using 100-day in-calf rate overcomes the difficulties of the calving index, which ignores cows culled for infertility, by calculating the proportion of cows intended for rebreeding that are back in calf again within 100 days of calving. On average, only 49 per cent of cows intended for rebreeding were back in calf within 100 days of calving (therefore, the 100-day in-calf rate was 49 per cent). This ranged from per cent between the bottom and top 25 per cent of herds. The herds with the highest 100-day in-calf rates had higher submission and conception rates, but also tended to be lower yielding mainly due to the influence of spring calving herds. Cost of herd infertility On average, the herd infertility cost for a 100-cow herd based on projected calving intervals and the cost of replacing cows potentially culled for infertility was estimated at about 18,000. This ranged from around 6,500 in the top 25 per cent of herds to almost 38,000 in the bottom 25 per cent of herds. The cost of replacing cows potentially culled for infertility at the end of the breeding season is the largest infertility cost. In spread calving herds, some late-calving or non-pregnant cows are carried over for service in the next breeding season and are not culled but, nevertheless, incur a considerable infertility cost with a longer calving index and a prolonged interval to peak milk production in the next lactation. This extended calving index is estimated to cost 1.50 to 3 per cow per day beyond 365 days, 4 / 10

5 depending on the average herd yield. Summary Dairy farmers in Northern Ireland can use FBO to assess their herds fertility performance. Heat detection efficiency and conception rates were highest in seasonal-calving, lower-yielding and smaller herds. The estimated cost of infertility is around 18,000 per 100 cows. However, this ranged from approximately 6,500 to 38,000 in the top and bottom 25 per cent of herds. References Esslemont R J, Kossaibati M A and Allcock J (2001). Economics of fertility in dairy cows, British Society of Animal Science Occasional Publication: Fertility in the High-Producing Dairy Cow 26 (1): Gaines J D, Thomas C B and Eicker S (1993). The interoestrous interval profile of a dairy herd: how useful is it? Veterinary Medicine 88: Mayne C S, McCoy M A, Lennox S D, Mackey D R, Verner M, Catney D C, McCaughey W J, Wylie A R G, Kennedy B W and Gordon F J (2002). Fertility of dairy cows in Northern Ireland, The Veterinary Record 150: Mayne C S, McCoy M A, McCaughey W J, Mackey D R, Verner M, Gordon A, Kennedy B W and Gordon F J (2003). Dairy Herd Fertility: Examination Of Effects Of Increasing Genetic Merit And Other Herd Factors On Reproductive Performance: End of Project Report No 3, AgriSearch, Dungannon. Morton J (2001). The InCalf Project Progress Report: A Reference Document For Farmers With Year-Round Calving Herds and For Their Advisers, Dairy Research and Development Corporation, Melbourne, Australia. Sreenan J M and Diskin M G (1992). Breeding the Dairy Herd, Teagasc, Dublin. 5 / 10

6 Figure 1. The Fertility Benchmarking Online development team at its launch. From left: David Mackey (CAFRE), David Kilpatrick (AFBI), Erica Chisholm (AFBI) and Martin Mulholland. 6 / 10

7 Figure 2. Annual distribution of calvings in different herds. 7 / 10

8 Figure 3. Screen image of the Fertility Benchmarking Online breeding records grid. The RB column can be unticked to indicate those cows that are not intended for rebreeding. 8 / 10

9 TABLE 1. Fertility benchmarking results for 90 dairy herds (top and bottom 25% of herds based on 100-day in-calf rate) 9 / 10

10 Powered by TCPDF ( 10 / 10