Over the next 3 months, the #MegaFertility campaign will be sharing the opinions of dairy experts from across the industry to raise awareness of some of the issues around dairy cow fertility. In our first article dairy farmer and zoologist, Phil Latham tells us his story of how he reached maximum fertility rates for his herd. Enjoy.
I’m just coming up towards 50 years old but when I came home to farm at the tender age of 21 I hadn’t much farming experience. I’d done a degree in Zoology but father insisted I learn some theory about farming and so I went to Reaseheath agricultural college to undertake a 1-year course specifically on the dairy herd management. Armed with this knowledge I arrived at home and got stuck in, knowing everything but understanding little.
I was surprised that fertility wasn’t that good which we assessed as conception rate to first service in our year-round calving system. I thought our Friesians were underperforming and introduced Holsteins to the breeding programme and I was frustrated by the size of the calf rearing bill from our rearer. An objective question about herd performance was ‘do we need so many replacements?’ We were operating at about a 25% herd replacement rate.
Equipped with the techniques that we were told were important to improve herd fertility I attempted to address what I thought were the key issues. We did heat detection 5 times a day. We took enough bloods to satisfy a greedy vampire for metabolic profiles. We kept accurate records with ADAS’ Datamate programme and used Genus’ Herdwatch, we looked at the diets, formulated rations, fed minerals, injected copper and retrained in AI techniques. Fertility went up, it also came down, we called this seasonality but in truth, it was because we weren’t in control. After 4 years I despaired that the theory was just that, impractical and I started to blame my team and the breed for the results. I sent 4 years of data to a professor of fertility who analysed the data and came back saying that our cows were on a metabolic knife edge. That may have been true but how do you avoid it, how do you manage it?
At this point I was introduced by BOCM Pauls, as it was then, to Dr Dirk Zaaijer, a Dutch vet specialising in fertility on farms, an early pioneer of embryo transfer (ET), a man who would rectal cows in an abattoir then wait for a post-slaughter analysis of ovaries to see if he’d described the structures on them correctly. During his ET work, he noticed that implantation success very much depended on the percentage of cows that were cycling normally, and he found that he could manipulate this ‘herd cyclicity’ through the diet alone. Small changes in the diet would have profound impacts on the level of anoestrus, the size of follicles, the percentage of cows coming bulling early after calving and there was a clear correlation between cyclicity and conception rates. I like the simplicity of it and the empowerment, believing you that you really can be in control, so we started using his services.
Every month we would fly Dirk into Manchester and spend the next day ‘rectalling’ every cow in our two herds that was over 21 days calved up to the point of service and those that had been pregnancy tested and were empty. In short out of combined population of 850 milkers we looked closely at the cycling portion of the herd that overcome the stress of calving. From this snap shot we could determine what percentage of cows were cycling normally.
The stage of the cycle was determined by the physical characteristics of the corpus luteum (CL) so we could plan when to look for oestrus as it turned from liver consistency to then being tight and finally hard. We could assess the abnormalities too. We quantified the percentage anoestrus, cystic, luteal cysts, follicular cysts, endometriosis and those where the corpus luteum was spongier. Spongy CLs were not those with a hole in the middle, a lacuna, they were larger and different and when Dirk finally got Utrecht university to ‘ovary-ectomise’ some cows that ‘were spongy’ they found the texture was related to the amount of blood vessels within them, they were more heavily vascularised. We looked at the changes in the percentages and the physical characteristics that were visible in the herd too. We looked at the change in body condition scores between groups, rumen fill, manure digestion and consistency and coat quality. I found the whole thing motivating. We had direction, a way to communicate and a system too. Data was important, if you don’t measure it you can’t manage it and the results improved. Replacement rate dropped to 15%, lactation yields improved, calving index stayed static and conception rates increased over 2 years from 42% to over 65% conception rate to first service and for 3 years the improvement was maintained. It was amazing how little we relied on hormonal interventions and good overall health was when cyclicity was good.
The challenge was to maintain the evident benefits of relying on nutrition. The problem I found was that while our nutrition models were good at predicting butterfat, protein and yield they were lousy at predicting fertility benefits. Energy was important but needed to come from a balanced source. We started feeding more bypass starch in the form of processed baby maize but to get a more consistent product we milled the maize through 3mm, 6mm, 8mm screens, increasing the size each time to get a larger particle size, eventually we elected to roll whole maize to almost a pigeon grit for best results. The models assumed these were all the same value but the particle size seemed to have a profound effect on the way they were metabolised. While we related anoestrus to energy particularly we were always concerned about rumen degradable protein levels being too high and we seemed to get high spongy CL levels when cows were on spring or autumn grass or when we fed over 1kg/day of rape meal. The key factor for us was all about nutritional balance.
Over time the results weren’t consistently high. Perhaps that was due to our arrogance that we understood things and lost objectivity. Yields carried on increasing the marginal litre became less profitable so we were inclined to feed less. Our expectations from forage consequently also increased and there’s no doubt that this put extra pressure on the cows we saw that declines in body condition scores were associated with poorer pregnancy results.
I think we learned a terrific amount about fertility manipulation during this period but I don’t have the answers, I believe I’m confused on a higher level and about more important things. The herd is now Brown Swiss and we want more from grass but we calve all year round and we need to improve our utilisation of forage. We focus less on conception rates now and more on submission rates and overall pregnancy rate objectives because we cannot find a replacement for the visionary vet who died many years ago. The game we play is the same now as it was then but as we adapt to a post-Brexit farm reality we may need to adopt new farming systems to create a sustainable margin. Whatever the system the diet is fundamentally important and the benefits of optimising fertility on farm economics should never but underestimated. I haven’t met a nutritionist who would accept being paid on optimising follicular quality apart from Dirk and that’s a great pity.