I’m working on the replacement problem on dairy cows.
In France, most of breeders raise all their heifers. Once a heifer calves, a cow is culled. However, the culled cow could continue his career and be profitable.
I need to know the risk of all cows in a herd to get mastitis (to increase cell count ), to be lameness and to have reproductive problems per parity, to estimate the longevity of this herd (how many cows culled in first parity, 2nd parity, in 3rd…).
Those information’s will help to calibrate a bio-economic optimization program which will indicate the optimal parity of culled cows.
andrewEnlightened
Does anyone know a model wich can estimate the longevity of a dairy cow?
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aron
I am working with HF X Canker crossbred herd at Livestock Research Station, Navara Agricultural University, Navara, Gujarat, India. We are also facing same problem with this herd. Therefore, we brought pure Kankrej cattle from another research station of Gujarat. This animals looked master of longevity. They are performing well even in 10th lactation. Mastitis is not much problem. Moreover, this animals are having good habit to sit on dry surface only which prevents teats from infection.
I recommend to add some blood of Kankrej animals to HF animals. The lactation yield of good Kankrej is near to 3000 liters with 4.5% of fat.
Andrew Pel
If you look at longevity as a heritable trait, then the primary factor is whether the cow stays in the herd for the first 60 days of the first lactation. The sire proofs focused on longevity use primarily first-lactation records and this seems to be highly reliable. So a model could use national breed data to look at why first lactation cows leave their herds in the first two months. Generally, first lactation cows comprise 25 to 35% of the herd, and this is the P1 is the mode for parity. In modelling this, one needs to use national data with some probability estimates for losses at various stages of 1st and 2nd lactation. Actually, mastitis, lameness and reproductive failure ARE NOT characteristic of farming systems but are more related to the level of management and level of production. At least in the USA, higher producing herds generally have lower mastitis and lameness, therefore can cull lower producers more quickly.
John Wick
I am not sure to understand your question.
If most French dairy farmers cull a cow for each heifer calving, that does not mean they do at random, but according to some criteria such as lameness, mastitis, reproduction failure, poor milk production, so probably culled cows are the less profitable as dairy cows. Culling rapidly cows and replacing them with heifers is a way to improve quickly the genetic merit of the herd. Moreover, a 4-5 year cow is probably easier to sell for meat than a 10-year one.
To my opinion, the risk to get mastitis, lameness, reproductive failure and so on is a characteristic of each farming system, so modifying the culling rules does not seem to be the better approach. It would be more efficient to address the causes of lameness and so on, and, why not, to model the bio-economic interest of changing the farming system (forex shifting from permanent stabling to pasture, or from corn silage to hay…).
Once again, the average parity of culled cows is an output of the farming system, not a lever as you suggest with “the optimal parity of culled cows”