Undertaking all-artificial-breeding approach to a herd’s mating programme is an emerging trend on New Zealand dairy farms.
That said, most farmers still rely on the conventional approach that typically involves an initial period of artificial breeding (AB) for replacement stock, followed by use of natural-mate bulls for tail-off time.
But where’s the proof of the pudding? Is there any difference in reproductive outcomes between the two approaches?
The short answer is no, says Joyce Voogt, LIC reproduction solutions manager and former vet.
“That’s based on big-picture numbers at least – at the individual farm level some farmers will have made the transition to all AB with more successful results, and some less so.”
In general however, formal research undertaken by Voogt, together with LIC colleagues Charlotte Gray and Lorna McNaughton, shows little difference between the two approaches (details are discussed later in this article).
Why go AB-only?
Reasons vary between farms, Voogt says, but farmer feedback suggests main motives include:
a desire to capitalise on a wider variety of AB semen products now available
the cost of an AB pregnancy compared to a natural mating pregnancy
supply shortages of good quality service bulls
automated heat detection systems making AB-only more feasible
reducing the required period of natural mating through the use of short gestation length (SGL) semen at the end of the mating.
How are AB-only herds going?
“We identified AB-only, seasonal calving, herds from the MINDA database – and picked out 145 that generated detailed Fertility Focus reports for the 2014/15 season,” Voogt says.
“We compared those 145 herds against 2883 AB plus natural-mate herds (with detailed Fertility Focus reports).
“Our comparisons included mating length (ML), herd size (n), 6-week in-calf rate (6wk ICR), not-in-calf rate (NICR), 3-week submission rate (SR) and conception rate (CR).”
Results were remarkably similar between the groups across all the parameters and quartiles of performance measured (see Figure 1)
The range of performance was wide in both groups
Average performance in these herds was similar to the 6 week in-calf rate (2014), which was 66.8 % for seasonal calving detailed FFR herds (Dairy Statistics 2014/15)
Herd sizes in both groups were similar, ranging from fewer than 300 cows to more than 2000 cows
Reproductive outcomes were compared between herds that did artificial breeding (AB) only and herds with a mixture of AB and natural mating (NM) Reproductive outcomes were similar between the two groups High reproductive performance can be achieved whether using AB only or AB plus NM To optimise performance, farmers should identify and address risk factors specific to their chosen system.
In short, the above suggests that similar performance outcomes are likely to occur whether farms elect an all-AB programme or an AB plus natural mating programme.
A high level performance is as equally possible in AB-only herds as in AB plus natural mate herds, Voogt says.
How to achieve target performance:
According to Voogt, there are eight key management areas that impact herd reproductive outcomes, namely: calving pattern; heifer management; body condition and nutrition; heat detection; dealing with non-cyclers; genetics and artificial breeding practices; bull management, and; cow health.
Getting cows well set up for mating is an important foundation, Voogt says.
“But once mating is underway more risk factors come into play, particularly when it comes to heat detection and service bulls.
“Heat detection risk factors are obviously more important when doing all-AB. As time goes on, heat detection fatigue and low sexual activity levels in the herds are significant challenges to overcome.”
On the other hand, when adopting natural mating, reproductive risk factors that a natural mate bull presents deserve close scrutiny. High-risk elements include bull health; bull numbers; fertility; and disease risk.
A more immediate, and arguably an even bigger risk, is the safety aspect that centres on both cows and people.
Through identification and mitigation of risk however, farmers can achieve top results with either system.
“If going AB-only, it pays to do your homework first,” Voogt says.
Check with your FSM if historic performance indicates all-AB is a suitable option for your farm
Talk to farmers who have been successful with this mating system
Get the processes in place to manage risks, such as extra heat detection aids
Consider the best semen options as you progress through the mating period
Monitor performance as you get into mating
Have contingency plans in place to address issues that might arise.
Reproductive outcomes were compared between herds that did artificial breeding (AB) only and herds with a mixture of AB and natural mating (NM)
Reproductive outcomes were similar between the two groups
High reproductive performance can be achieved whether using AB only or AB plus NM
To optimise performance, farmers should identify and address risk factors specific to their chosen system