30 août 2017
Non-Injectable factors to improve reproduction
Kimberly J. Egan, DVM, Dairy Consultant Manager, GENEX
It is frustrating to hear the only thing standing between a herd and a 30% pregnancy rate is the lack of injections from a synchronization program. Don’t get me wrong, well-timed synch programs with excellent compliance will increase insemination rates versus heat detection alone and have been proven to improve fertility. However, many factors affect conception. What follows is data which may are new your interest in non-injectable factors—management factors—that improve reproduction and benefit your bottom line.
Good reproduction is one key to increasing production efficiency per stall. A cow may still be giving 80 lbs per day at 400 days in milk, but is she the most profitable cow to occupy that stall? Ideally, she would be fresh into her next lactation and on her way to peak milk.
A well-timed synchronization program with excellent compliance may help boost a reproduction program and increase production efficiency per stall but don’t overlook other important areas that can also help to improve reproduction in your herd.
Udder Health. Many people are surprised by the impact udder health can have on conception rates. In the GENEX Dairy Performance NavigatorSM (DPNSM) program, data from over 115,000 cows in herds between 501 and 2,000 head shows a significant increase in conception rates as somatic cell counts (SCC) decrease. Over the last year, conception rates were 3% higher for first lactation cows under 200,000 SCC. Even more improvement in conception was seen in older cows: second and later lactation cows under 200,000 SCC had 7-8% higher conception rates than their contemporaries with higher SCC. Therefore, management plans to improve udder health can have positive effects on the reproductive program as well.
Transition, metabolic disease and body condition. In 2007, Walsh et al. reported a 20% reduction in the probability of pregnancy at first service for those diagnosed with subclinical ketosis in the first and second weeks postpartum, there was a 50% reduction in probability of pregnancy at first service.2 Combine this with the nearly 30% prevalence rate3 of subclinical ketosis, and it is no wonder herds struggling with metabolic issues see adverse effects on conception.
The same negative energy balance associated with early lactation can lead to losses in body condition as well. Research published in 2014 found an 8.8% decrease in pregnancies per A.I. in cows with body condition below 2.5 versus those with a score at or above 2.75 at the time of breeding.4 in other words, a small difference in body condition score can have a significant impact on reproduction.
Genetics. Daughter Pregnancy Rate (DPR), Cow Conception Rate (CCR) and Heifer Conception Rate (HCR) are fertility traits included in genetic indexes such as lifetime Net Merit $ and Ideal Commercial Cow $.
An example of the impact genetics, namely fertility traits, can have on annual conception is shown in the graph above. The graph is based on data from a large Midwest dairy and shows annual conception rates for first lactation females and second and later lactation females of differing DPR values. All DPR levels are based on genomic results, and each group has at least 120 cows.
As the graph shows there is a continuous trend toward higher conception with improving DPR. The results show the difference in annual conception rate even though these cows experience the same protocols, comfort and ration.
Footing. Any herd that wants to maximize natural heat detection should pay attention to footing. Biosolid bedding can lead to a slippery biofilm on concrete, and concreate flooring may need to be re-grooved periodically. The difference good footing can make was described by Britt et all., showing the total number of mounts or stands were reduced by about half when moved from dirt to concreate.5 Freestall barns provide a life of leisure for cows, but attention to floor condition is a must.
Stress. The most commonly addressed culprit of reduced conception rates is climate (i.e., heat and humidity). The impact on reproduction, feed intake and production are well known. Other common stressors are nutritional and managerial. This may include inadequate push-up of feed, inadequate bedding or limitation on lying time or space. Stress has physical ramifications that are only beginning to be understood. The neuroendocrine, immune, cardiovascular, reproductive and central nervous systems are all part of the same animal and effects in one system evoke changes in the others.6
A strong reproductive program cannot be built on a faltering foundation. A herd experiencing a high rate of mastitis, or a running bout with subacute rumen acidosis, is not going to achieve award winning pregnancy rates by adding injections or tweaking shot timing…it just might be a couple ticks better than before. The way to make a reproductive program strong may look a bit different depending on geography, but it is not just a synch program. Good genetics, cow comfort and diligent management are common denominators.
Dairy Performance NavigatorSM program. 2/19/17
Walsh, R.B., J.S. Wlaton, eta al 2007. The effect of subclinical ketosis in early lactation on reproductive performance of postpartum dairy cows. J. Diary Sci. 90:2788-2796
McArt, J.A., D.V. Nydam, and G.R. Oetzel. 2012a. Epidemiology of subclinical ketosis in early lactation dairy cattle. J. Diary Sci. 95:5056-5066
Carvalho PD, Souza AH, etal. J Diary Sci. 2014; 97(6):3666-83. Doi:10.3168/jds.2013-7809. Epub 2014 Apr 14. “Relationships between fertility and postpartum changes in body condition and body weight in lactating diary cows.”
Britt et al., 1986; Determinants of estrous behavior in lactating Holstein cows. J. Dairy Sci. 69:2195-2202
Kelley KW, Johnson RW, Dantzer R: Immunology discovers physiology. Vet Immunol Immunopathol. 1994, 24:157-165. 10.1016/0165-2427(94)90132-5.