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High yields should not be a barrier to fertility

Improved cow fertility and reproductive performance is a shining beacon in an otherwise depressed industry. Ann Hardy delves into what the latest set of NMR figures have to tell us.

Heat detection has improved, specialist Mike Halliwell says investment in this is ‘money well spent'
Heat detection has improved, specialist Mike Halliwell says investment in this is ‘money well spent'

Asignificant jump in the percentage of cows served within 80 days of calving and an increase in the number of cows in-calf by 100 days has been reported by NMR. This reflects a sea-change in dairy cow management and demonstrates the importance of choosing straightforward measures of performance to benchmark one herd against another.

This information comes from the University of Reading’s recently published report of Key Performance Indicators (KPIs) which has benchmarked the performance of 500 NMR-recorded herds (mostly same) since 2010.


It compares 32 health, fertility and production parameters from a crosssection of black-and-white herds which – because the herds are randomly selected from all those herds recording with NMR – are claimed to be representative of recorded herds throughout the UK.


The middle value for the percentage of cows served by day 80 was found to be 57% in 2015, compared with just 46% in 2010. (See table, p60). One in four herds reached 67% served by day 80 in 2015, an improvement of eight percentage points over 2010.


James Hanks of Pan Livestock Services, co- author of the report, says the 80 day served rate is one of the best parameters by which to benchmark reproductive performance.


He says: “Consistent increases in this figure over the five years tells you how much farmers have improved when it comes to getting cows served early.”


In addition, he points out the overall conception rates have remained almost unchanged at an average 32% across the five years, despite the earlier services.


Highlighting improvements in heat detection, he refers to another parameter he considers important, which focuses on the interval between services – the percentage of service intervals at 18-24 days.


“Ideally a cow failing to conceive at one service will show oestrus and be served again at the next oestrous cycle, around 21 days later,” he says. “Measuring the percentage of service intervals which are around that length (18-24 days) is a useful measure of the herd’s heat detection, as it represents the percentage of cows reserved at the first available opportunity.”


Dr Hanks is less enthusiastic about the popular measure of pregnancy rate which he says can be useful at the individual herd level but misleading when comparing performance between herds.


“Pregnancy rate is very vulnerable to differences in voluntary waiting period [VWP] and how you deal with barren cows,” he says.


Remarking pregnancy rate represents an amalgam of heat detection, conception rate and VWP he says: “Why not just look at each trait individually? “Pregnancy rate is a measure which can cause confusion so it’s generally preferable to ask the simple questions, how quick, how many, how often?” he says.

Comparison of median and target values derived from the study of 500 NMR recording herds in 2015 with the original study in 2010

Parameter Median Median


(best 25%)


(best 25%)

Year of the study 2010 2015 2010 2015
A. Culling rate 24% 24% 18% 20%
B. Culling/death rate in first 100 days of lactation 7% 5% 4% 3%
C. Age at exit (years) 6.6 6.3 7.4 7.0
D. Age at exit by lactations 3.9 3.7 4.5 4.2
E. Percentage served by day 80 46% 57% 59% 67%
F. Percentage conceived 100 days after calving 26% 32% 33% 39%
G. Calving to first service interval (days) 105 80 87 71
H. Calving interval (days) 424 410 409 396
I. Age at first calving (years) 2.4 2.3 2.3 2.2
J. Conception rate 32% 32% 40% 39%
K. Percentage service intervals at 18-24 days 30% 34% 38% 40%
L. Percentage service intervals >50 days 32% 24% 22% 16%
M. Percentage eligible for service that were served 27% 33% 37% 41%
N. Percentage eligible for service that conceived 9% 11% 13% 15%
O. Lifetime milk/cow/day (kg) 10.5 11.9 12.6 13.9
P. Milk/cow/year (kg) 7,665 8,222 8,760 9,313
Q. Average protein% 3.27% 3.30% 3.33% 3.36%
R. Average fat% 3.96% 3.96% 4.12% 4.11%
S. 305 day yield (kg) 7,400 7,905 8,300 8,813
T. Average SCC (‘000 cells/ml) 210 184 169 151
U. Percentage SCC >=200,000 cells/ml 24% 20% 19% 16%
V. Percentage SCC >500,000 cells/ml 9% 7% 7% 6%
W. Percentage first recording SCC >=200,000 cells/ml 20% 17% 15% 13%
X. Percentage chronic SCC >=200,000 cells/ml 14% 11% 10% 8%
Y. Percentage dry period cure (High:Low) 74% 75% 80% 82%
Z. Percentage dry period protection (Low:Low) 84% 86% 89%


ZA. Percentage low at end of previous lactation
(SCC<200,000 cells/ml)

60% 68% 70% 76%

New attitude

Reproduction specialist, Mike Halliwell from World Wide Sires, believes the trends are an illustration of a new attitude among farmers to reproductive performance and the collaborative efforts made between farmers, nutritionists and vets.


He says: “There was a historical feeling cows giving a lot of milk did not need to get in-calf so soon, as farmers felt they would be profitable through an extended lactation.


“However, it has been well proven the more frequently a cow calves the quicker she’ll return to peak production, and if she’s at a high production level for longer during her lifetime, this is unequivocally more profitable.”


Part of this success, he says, is an appreciation of the importance of the transition period which has been a focus of management attention for a number of years.


“It’s not just a fad, it’s absolutely the right thing to focus on and people have now improved transition management beyond recognition,” he says.


Heat detection, he says, has also improved and he believes any investment in this area is ‘money well spent’.


“This could be extra labour for heat observation or any technology – from scratch cards and tail paint to activity monitors,” he says. The idea that an early service will result in a poorer conception rate he also debunks and says: “The cow is programmed to reproduce, and if she is kept healthy and in the right energy balance she is well able to conceive.


“Every farm has cows at a similar production level and one will conceive at 50 days and the other at 150,” he says. “Production has not been the limiting factor – it’s about the energy status and health of that cow around her production.”


Genetics must not be overlooked as a contributor to fertility and Marco Winters, head of genetics for AHDB Dairy, says the period of this report is particularly significant.

“Fertility Index was introduced in the UK in 2005, so until that point the genetics of dairy cow fertility had been on a downward trend,” he says. “From that point onwards, UK breeders have selected bulls with increasingly good daughter Fertility Indexes, so by 2010, many of these animals would have started to feed through to the national herd.”


The good news, he says, is there is much more improvement to come, as that genetic trend has continued – without compromising milk production – until the present day.


The Reading University figures bear this out, with a whole cross-section of fertility parameters continuing to rise.


This includes a 14-day reduction in the average calving interval, from 424 days to 410 days, while one-infour herds now achieves a calving interval of 396 days or less.


Most importantly, production also continues to rise, as improved health as well as fertility have contributed to an increased median 305-day milk yield of 7905kg, some 505kg more than in 2010, while the average yield achieved by the top 25% of herds is now 8813kg.

Lifetime daily yield

“Particularly important, in view of its impact on herd efficiency, is the improvement in lifetime daily yield,” adds Dr Hanks. “There’s been an increase in the median from 10.5kg/day in 2010 to 11.9kg/day in 2015, while the current target, set by the top 25% of herds, is 13.9kg/day.”


Producers should be commended for the improvements they have made and encouraged by these trends, according to Dr Hanks. He says: “I would urge every herd to record its performance which will show progress and help set targets without which it is hard to improve.


“The target, achieved by the top 25% for each parameter, is realistic and achievable for most in the industry, but the best course of action is to discuss the results with your vet or advisor who will help with their interpretation.”


  • The Key Performance Indicators for the UK national dairy herd: A study of herd performance in 500 Holstein/Friesian herds for the year ending August 31, 2015, by Dr James Hanks and Dr Mohamad Kossaibati, can be downloaded from

SCC is improving

  • Outstanding improvement has also been made by dairy farmers for somatic cell counts according to the report. “While in 2010 a herd SCC of 210,000cells/ml put you in the top half of producers, you now need a SCC of 184,000 cells,” says Dr Hanks. “Only one herd in four now has a herd SCC over 228,000 cells, whereas back in 2010 one in four herds were over 268,000 cells, so this represents outstanding progress.”



Median and average

  • The median is used as the average for this study as it removes the distorting effect of extremes. This is particularly useful for fertility parameters which can reach extreme values. The median is the middle value in a distribution. The mean, which is the more commonly used average, is calculated from the sum of the values divided by the number of values. As such, it is more distorted by extremes and can, in some circumstances, be less representative of the true picture.
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