What type of cow will be suitable for a quota-free world?

Donagh Berry said: “It is vitally important that Irish dairy farmers continue to select for a resilient cow that is balanced and capable of consistently delivering high profit. The Economic Breeding Index (EBI) is identifying such genetics. Not alone is the EBI reducing the costs of production, but it is also increasing milk solids.

“The genetic trend for milk solids in Ireland is increasing at a comparable rate internationally; there is more emphasis in the EBI on milk production than in countries like the US and the Netherlands.

“Moreover, the EBI is simultaneously selecting for improved reproductive performance, thereby facilitating earlier calving and longer lactations; with a fixed dry-off date, a March first-calving cow will yield 6% more than an 1 April calving cow (that is, 312kg for a 6,000 litre cow).

“Furthermore, the EBI is selecting for greater cow survival, thereby not only reducing the cost of heifer replacements, but also resulting in an older herd cow profile and thus achievement of the mature herd genetic yield potential.

“A mature cow will yield, on average, 22% more than a first-lactation cow. For example, in a 100-cow herd, the increased herd milk output gained by reducing the proportion of first-lactation animals (that is, replacement rate) from 26% to 20% will be equivalent to having one more cow in the herd.

“In summary, there are more ways to increase herd output than selection directly for milk production; the overwhelming advantage of latter two approaches is that they will also reduce costs.”

What is the best advice for those considering using sexed semen?

Stephen Butler: “Sexed semen is suitable for herds that are currently achieving high levels of fertility with conventional or normal semen (that is, about a 70% conception rate in heifers and about a 60% conception rate in cows). Use sexed semen on replacement heifers that have been well reared and the early-calving cows. These are the most fertile animals in the herd. A heifer calf is also likely to reduce calving difficulty.

“Ensure heifers are well-reared, have reached target weights and are cycling regularly by mating start date. Early-calving cows should be calved at least nine weeks, and have a BCS of 3 at least. Like normal semen, make sure you use a team of bulls. The semen from an individual bull may have poor fertility after the sorting and freezing process.”

What conception rate can I expect in milking cows if I use sexed semen?

Stephen Butler said: “Assuming sexed frozen semen achieves pregnancy rates that are 87% of conventional semen, the conception rate will vary depending on the fertility status of the herd. A high conception rate for a milking herd is 60%, so hence the conception rate using sexed semen will be 51%.

“An average conception rate of 50% will mean you get a 43% conception rate with sexed semen. A low conception rate of 40%, which happens in many herds each year, will deliver a 34% conception rate if you use sexed semen. This is a very low success rate and the main reason why it is not advised to use sexed semen in low-fertility herds.”

Ongoing fertility trials

Two American researchers, Matt Lucy and Paul Fricke, are on a research sabbatical in Moorepark, working on trials related to cow fertility. I asked them to explain what they are doing in their fertility trials.

Glucose on cow fertility

Matt Lucy is looking at the effect of blood glucose on cow fertility. Matt said: “It has been well demonstrated that glucose is a critical nutrient for the dairy cow because of its role in milk synthesis, but it is also required to establish pregnancy while the cow is lactating.

“During early lactation, nutrient requirements for milk production exceed nutrient intake, resulting in negative energy balance and reduced circulating glucose concentrations. We are currently conducting research to examine the effect of circulating blood glucose on the reproductive physiology of the cow during early lactation and also during early embryo development.”

On the early postpartum cow, Matt said: “The timing of the restoration of ovarian cyclicity is largely dependent on the metabolic status of the cow. We are testing the role of glucose as a key signal in the processes of uterine involution and restoration of normal ovarian cyclicity.”

Of the pregnant cow, Matt said: “We observed that less glucose reaches the foetus in a milking cow, perhaps because her circulating glucose concentrations are lower. We are testing the role of glucose as a key signal that regulates foetal growth and survival.”

Progesterone

Paul Fricke is working with Stephen Butler, assessing the effect of progesterone on fertility in milking cows.

Paul said: “Reproductive performance is the key to profitability in seasonally calving, grazing-based dairy herds in Ireland. Early pregnancy losses in lactating dairy cows are problematic for dairy farmers because they decrease conception rates and increase the interval between inseminations.

“Both of these factors limit profitability by decreasing the rate at which cows become pregnant, thereby decreasing the compactness of the calving period. Our objective is to assess the role of progesterone during embryo development. Our hypothesis is that a low-progesterone environment will mean high embryo losses.

“This experiment has particular relevance for non-cycling cows. The proportion of non-cycling cows near the time of breeding varies among herds and has been reported to range from 15% to 30%.

“Cows that start the Ovsynch synchronisation protocol when blood progesterone is low have fewer pregnancies and more pregnancy losses than cows that initiate Ovsynch when blood progesterone is high.

“Although inclusion of a progesterone insert (CIDR or PRID) during synchronisation can mitigate some of these negative effects, blood progesterone concentrations in non-cycling cows with a progesterone insert may not fully overcome these problems.

“Results from this experiment will be useful to define the physiology leading to poor reproduction caused by low progesterone and to potentially identify better treatments for non-cycling cows.”

Milking robot research

Cathriona Foley and Bernie O’Brien are working on the milking robot that has been on the Kilworth farm for the last three years.

Cathriona said: “The 2014 calving season began in mid-January and as of last week there are now 67 out of 70 cows milking on the robot with an average calving date of mid-February.

“In February, cows were fed silage indoors at night and outside grazing from 8am to 4pm. Since late February the herd has been grazing full-time outside, transitioning between the three grazing blocks – A, B and C – at 8am, 4pm and 12am, respectively.

“This means that if a cow leaves grazing block A for the milking robot after 8am, she will automatically be drafted to grazing block B when she decides to go back to grazing once she is milked.

“The intention is to use the allocation of fresh grass to entice the cow back to the milking robot rather than meal. The milking herd are being allocated 4kg grass DM/cow in each block in each 24 hours (12kg/day). All cows are fed 4kg of meal per day.

“The current milk production for the herd on the milking robot is 23 kg/day with 4.8% fat, 3.5% protein and 4.7% lactose. To date, somatic cell counts are satisfactory, averaging 115, 000 cells/ml. The research this year will compare 1.5 milkings per day compared with the normal two times per day.”

Open day

On Wednesday 9 April there will be an open day on the Dairygold research farm in Kilworth which is adjoining the main research station in Fermoy for all dairy farmers. Admission is free. The open day starts at 10am and the focus will be to hear the latest research on reproductive performance in advance of the breeding season and how to manage fertility and body condition score. Farmers will also be able to see the milking robot in action and discuss the latest research results. Once farmers have toured the stands and heard the research messages, there will be an open discussion forum where farmers can seek answers to questions that remain unanswered.

What: Teagasc Open Day.

Location: Kilworth Farm, Kilworth, Co Cork.

Date: Wednesday 9 April 2014.

Time: 10am to 3pm.