Ten facts about breeding more profitable cattle
By Dr Steven Johnston, Senior Beef and Sheep Technologist, Greenmount Campus, College of Agriculture, Food and Rural Enterprise
Introduction
EBV means Estimated Breeding Value. This is a measure of the genetic ability of an animal. An EBV is calculated from all the available performance records of an animal itself as well as its relatives in many different herds. To produce accurate EBVs performance information such as 200-day weights, 400-day weights, muscle and fat depths, gestation lengths and calving ease are measured and analysed using Best Linear Unbiased Prediction (BLUP).
Data from two CAFRE student-learning projects, L.I.M.O. and U.P.L.A.N.D.S., clearly demonstrates that EBVs deliver the goods. The L.I.M.O. herd comprises 50 purebred and ¾ bred Limousin cows and is based at the Abbey farm, Greenmount Campus. U.P.L.A.N.D.S. is based at Greenmount Hill farm and includes a 110 self-sustaining suckler cow herd combining Shorthorn, Aberdeen Angus and Limousin genetics mated to Charolais and more recently Aberdeen Angus bulls.
The Facts
Fact 1: BLUP is the method now universally recognised as being the best for estimating the genetic worth of animals.
The big benefit of BLUP is that it is able to remove the influence of environmental factors such as management and feeding when assessing each animal.
Fact 2: Select cows with negative Gestation Length EBVs to shorten the gestation period.
Based on 96 observations, the data suggests that as gestation length EBV is reduced by 1 day the actual gestation period for the cow is reduced by 0.7 days. Breeders’ who aim to have a compact calving should select stock with a negative gestation EBV.
Fact 3: Selecting for low Birth weight EBV reduces the size of calves at birth.
Based on 130 observations, each reduction of 1 kg of cow birth weight EBV resulted in an actual 2kg reduction in calf birth weight. This means that a cow with a negative EBV value for birth weight will produce lighter calves at birth. Couple this with using a bull that has a negative birth weight EBV and calving time should be less stressful.
Fact 4: Select for positive Calving Ease EBV and reduce the number of difficult calvings.
Based on 128 observations, the average calving ease EBV for the cows within the L.I.M.O. herd is –1. On average each cow is given slight assistance at calving time, rated as a score of 2 on the scale 1 to 5, where 1 = no assistance and 5 = caesarean. Each 1pt increase in calving ease EBV resulted in a reduction in calving score at calving time of 0.2. This suggests that those breeders who cannot afford to have difficult calvings should purchase stock with as high a positive calving ease EBV as possible.
Fact 5: Cows with positive 200-day milk EBVs will produce heavier calves.
Based on 71 observations, each 1 kg increase in 200-day milk EBV resulted in 6 kg heavier calves at 200 days. The costs of keeping the cow will be the same irrespective of what size of calf she rears, so ensure she rears a bigger calf by selecting for positive 200-day milk EBVs.
Fact 6: Selecting for 400-day growth EBV increases both daily live weight gain and final carcase weight.
Based on slaughter information from 79 animals, each 1kg increase in 400-day growth is equivalent to 0.7kg of increased carcase weight achieved by higher daily live weight gains. Increasing the efficiency of beef production, through increasing carcase weights and reducing the age at slaughter period should be the aim of every beef breeder if they are to survive in the global market place.
Fact 7: Selecting for increased muscle score and muscle depth EBVs will increase carcase conformation.
Based on slaughter information from 79 L.I.M.O. animals each 1-point increase in Muscle Score EBV results in an improvement of 0.57 in carcase grade. The relationship between muscle depth and carcase conformation is also positive.
Fact 8: Selecting for negative Fat depth EBV will allow cattle to be slaughtered at heavier weights.
Based on slaughter information from 79 L.I.M.O. animals, there is a highly significant relationship between the Fat depth EBV and carcase fat class. Each 1 mm change in fat depth is equivalent to one fat class.
Fact 9: Selecting for a higher Beef Value Index will increase carcase value.
Based on slaughter information from 79 animals, there is a very highly significant relationship between the Beef Value Index and the carcase value of the animal. Each £1 increase in Beef Value is equivalent to £3.50 in actual carcase value.
Fact 10: The Northern Ireland Beef Industry cannot afford to ignore the benefits of EBVs.
Everyone can rely on EBVs to deliver more profitable cattle. At the Greenmount Hill Farm, replacing an average Charolais bull, with a Beef Quality Initiative designated Elite Carcase Charolais bull, increased returns per calf by £150. This is similar to the old suckler cow premium and demonstrates how breeders can replace subsidies with efficiency gains delivered through adoption of modern technology.
In Summary
Each individual breeder must prioritise the breeding goals for their suckler herd within a breeding strategy and use EBV based selection criteria to maximise efficiency gains. In practice this means making optimum use of EBV data when selecting sires for natural service or through AI.