It’ll quickly be weaning time; the time to take into account making culling decisions since these can have a long-term impact on the competitiveness and profitability of your cow herd.
There are lots of causes to cull. Being open tops the record as an open cow won’t ever pay her approach out of a misplaced 12 months of manufacturing. Different components embrace temperament, age, bodily points (toes and legs), dangerous udder, dangerous eyes and body dimension.
On this column, I’m going to give attention to calf efficiency. To begin, solely consider calves which might be in the identical modern group — animals of the identical intercourse which might be born and raised collectively.
Metrics to take into account
There are a number of metrics to consider a cow primarily based on her calf’s efficiency:
Weaning weight. That is used to consider variations in calf progress charges and the cow’s milk manufacturing. This weight needs to be taken between 150 and 160 days of age.
205-day adjusted weaning weight (aWW). Older calves will possible weigh greater than youthful calves, however they might not have larger progress potential. For business producers, start weights might not be obtainable. If that’s the case, use a normal weight of 75 kilos for males and 70 kilos for females. As birthweight of calves out of different-age cows has been proven to differ, this additionally needs to be adjusted.
Lastly regulate for the change in milk manufacturing at completely different cow ages. The next desk offers that data.
Different metrics that can be utilized to consider a cow embrace weaning effectivity, the proportion of calf weight to cow weight that provides a measure of the effectivity of the cow; and most possible producing capability (MPPA). Utilizing the weaning weight of her calves over time, this calculates her superiority or inferiority as in contrast to her herd mates. For this column, I’ll give attention to weaning weight.
These values in of themselves usually are not very useful in figuring out what cows to cull. The subsequent step is to evaluate the person cow values to the herd common. Referred to as ratios, they’re a technique of deciphering data by dividing the person worth of curiosity by the common of the herd:
An animal that has a ratio of 95 weighs 5% lower than the common, whereas one which has a ratio of 120 weighs 20% greater than the common. A ratio of 95% is a typical benchmark for culling, however you possibly can select your individual benchmark.
The desk under can be utilized to follow calculating the adjusted 205-day weaning weights and ratios. It additionally serves for example. Cow 103 is 2 years previous and weaned a calf with a 205-day weaning weight ratio of 92%. Cow 46 is a 4-year-old that produced a calf with an 89% ratio.
The temptation can be to hold these cows as a result of they’re younger and definitely will enhance. Keep in mind, although, that every cow had weight added to her calf due to her age — 60 kilos for 103 and 20 kilos for 46.
In accordance to analysis from … Arkansas, “Most cows ranking in the bottom one-third of the herd for calf-adjusted 205-d BW ratios consistently ranked in the bottom one-third of the herd over a period of several years, regardless of cow age.”
Take into account that the above suggestions are primarily based on “all things being equal.” If there are distinctive circumstances reminiscent of well being or damage, then some interpretation may very well be made.
The underside line is in case you have primary data in your cows and calves, you possibly can flip this data into data that can be utilized to present steerage in figuring out what cows to cull.
For extra data, search the web for “BIF Guidelines” and “adjusted weaning weight calculator.”
Baker is a senior Extension affiliate within the Cornell Division of Animal Science.