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Angus GROUP BREEDPLAN EBVs

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Getting the most out of Breedplan - Increasing the accuracy of your EBVs
65 - Management tips to increase the accuracy of your EBVs
66 - How to handle Breedplan in a drought
67 - Weighing and scanning pregnant heifers

65 : Herd management tips to get the most from Breedplan, and to increase the accuracy of your EBVs.  

It is important to ensure that your recording procedures optimise the accuracy of the EBVs estimated for your herd. Most problems encountered which perceive a lack of credibility of Breedplan EBVs for some particular animals can be explained by biases brought about by incorrect data recording or herd structure.

The recipe for increasing the accuracy of your EBVs is to keep management groups as large as possible and to ensure linkage between groups of calves, therefore,

• Weigh calves before they are separated into different management groups, for example before some of the males calves are castrated, or before some will be preferentially fed. Where you have to split a group before weighing, make the split on the basis of sex of calf (sex groups are analysed separately anyway), and then on calf age if a further split is required.
• record the first weight as close to the group average age of 200 days as possible. Leaving the “weaning weight” until physical weaning means that some of the older calves may be already/almost weaned and that the influence of milk on that weight is reduced.
• Record as separate management groups, any animals (or group of animals) that have been managed differently to the extent that their performance could have been influenced. (For example feeding a group of bulls for sale whilst the remainder of the drop are pasture reared, calves that were badly affected by scours or pink eye, mixed sex calves from a group of cows run on improved pasture versus a group on unimproved pasture)
• Weigh all calves of the same sex on the same day, as different weigh date groups are treated as different management groups. Where groups of the same sex are weighed on following days it is more accurate to record a common weigh date than have the groups split. (Don't leave half the group in the yards overnight otherwise you will record large differences in gut-fill, not body weight - different groups of calves should be weighed after the same curfew period).
• Time AI programs to coincide with natural mating, or include a sire from the natural mating in the AI program, to avoid the AI group being genetically isolated from any comparison.
• Ensure more than one sire is represented in each management group by boxing cows and calves after mating and reforming mating groups at weaning each year.
• Don't change all your sires in the same year, rather have a carry-over of sires from year to year.
• Have a compact calving. This increases the number of calves in each group and reduces the number of groups based on calf age. A calving spread of 6-10 weeks is ideal.
• Don't join the same sire to the same group of cows each year, such as can happen when cows are set stocked in year-of-drop groups. It is better to re-allocate cows and sires to joining groups each year, and where this is not possible then ensure that more than one sire is joined to each "isolated" cow group, and that sires are rotated amongst groups from year to year.
• Don't only record the better calves as this will cause considerable bias in the EBVs. Weigh and record all calves before culling. See topic 25.
• Weigh and record steer calves. For sure you won't be breeding from them but they do get their genes from the same parents as their brothers and sisters. Their record does contribute to the individual record of their sire and dam, and to the genetic profile of the herd or breed in general.
• Record the pedigree, calving ease and, if possible, the birth weight of dead calves (including those that die within 48 hours of birth).

66 : Keeping Breedplan going during a drought . . . . . . . . . . . . . Go to Top

Owners of Breedplan herds in drought affected areas have more pressing worries than the finer points of Breedplan I'm sure, and it will be tempting to drop recording for awhile.

However, with a little effort it is often possible to keep the essentials going and thus avoid a major gap in the recording history of your herd. It also helps protect the investment you have made in your performance recording program. A few things to consider are ;

(i) Don't avoid submitting low drought affected weights in the fear that they will lower your EBVs. Cattle are only compared in like treatment groups, so the drought affected calves should not be disadvantaged.

For example if your yearlings average 300 kg animal at 320 kg will have a similar EBV to a 420 kg animal in a 400 kg average group with a better season.

(ii) There will be situations where it is not be possible, or worth while, collecting weights, for example no facilities at the agistment site, cattle on the road, or hand feeding with uneven distribution.

Where possible keep the pedigree records for these animals and submit a later weight when the job is back to normal, for example, miss the weaning weight but submit a 400 and/or 600 day weight at a later date.

(iii) Where groups of cattle are away on agistment or receive different levels of feeding, note groups treated differently by giving them separate management group codes.

67 : Weighing and Scanning Pregnant Heifers . . . . . . . . . . . . . Go to Top

The first 1/ 3 of pregnancy has relatively little effect on the heifer's weight. Beyond that it starts to become significant, particularly in the last third.

As a general rule, therefore, weights from heifers more than 3 or 4 months pregnant should not be submitted to BREEDPLAN. An exception to this would be for synchronised matings or short joining, where only pregnancy tested heifers have been retained. If so, their weights are acceptable up to 5 to 6 months pregnant, as they will be at similar stages of pregnancy. Any slight bias will be in favour of early conceiving heifers.

600-day weights can of course be taken any time after 500 days. So if, for example, a breeder wished to submit '600-day weights' on heifers joined at 15 months (450 days) it would be preferable to take the weight when they are about 3 months pregnant, ie. 18 months (around 550 days), rather than going closer to the 600-days.

As for all other weights, pick a time that suits management and while the heifers are in as large groups as possible, eg. taking a weight before splitting into separate joining groups.

Scanning : Valuable information can be gained by scanning heifers, in particularly to allow better evaluation of their sires.

The weight taken at scanning is used in the calculation of the carcase EBVs. If this weight were 'distorted' by pregnancy, it would have very little effect on the fat EBV, a small effect on the eye muscle area EBV and a moderate effect on the yield EBV. Heifers should therefore not be scanned for BREEDPLAN if they are more than 3-4 months pregnant. An exception would be for synchronised matings, as discussed above.