Agreement of Predicted 305-Day Milk Yields Relative to Actual 305-Day Milk Weight Yields

Abstract

The objectives of this study were to compare the multiple trait prediction (MTP) model estimate of 305-d lactation yield with the 305-d daily milk yield data from on-farm automated meters and software and to examine the accuracy of electronic identification (ID). Twenty-four-hour milk and component yields are calculated by using milk weights and samples collected 8 to 10 times/yr by Dairy Herd Improvement (DHI) organizations. Daily milk weights were collected from cows on 20 Canadian farms that used parlor milking systems with electronic ID and that were enrolled in a regular DHI program. A total of 10,175 DHI test days from 1,103 cows with complete 305-d lactation yields were entered into the MTP model, and lactation yields were predicted. Test days were grouped into first, second, and third and greater lactations and within each lactation group, days in milk were categorized in 3 stages (5 to 60, 61 to 120, and 120 to 305 d in milk) for a total of 9 classes. Agreement analysis was used to compare the 305-d sum of daily milk to the MTP 305-d lactation yield predictions by using inputs from test days throughout the lactations. Results indicated that the MTP model overestimated lactation yields across all parity groups, ranging from 310 to 1,552 kg in parity 1, 640 to 2,000 kg in parity 2, and 567 to 1,476 kg in parity 3 and greater. A preliminary examination of electronic ID accuracy was conducted on 4 farms. Two electronic ID systems were examined for cow ID accuracy by verifying the ID number appearing in the parlor with the corresponding ear tag number. There were no ID errors on 3 of 4 farms tested and only a very small number of errors (3/80) on the fourth farm, indicating that the electronic ID systems used in milking parlors identify cows accurately.

Modeling lactation curves of Polish Holstein-Friesian cows. Part II: Prediction of 305-d lactation milk, fat and protein yields

“…second-order, LEG3 and LEG4) were investigated, and the mean 305-d yields predicted by all the lactation curve models were higher than those computed by TIM. According to Quist et al (2007), MTP overestimated 305-d yields to a considerable extent in early lactation and more accurately estimated the yield in the later part of the lactation. Our results also showed that the accuracy of MTP depends on the number of TD records available but the opposite trend was observed in early lactation ( Figure 1).…”

Effects of postpartum uterine diseases on milk production and culling in dairy cows

“…On the other hand, previous studies used daily measurement of milk production, whereas the present study used monthly test-day measurements. The 305-d projection from the third DHIA test was used for estimation of full lactation production because this measure was more accurate than those based on the first or second test days (Quist et al, 2007). Although test-day measurement is reliable for full lactation measurements, it may not be the most sensitive method to detect the detrimental effect of metritis on milk production, which appears to be of short duration.…”

Assessing the Association of the Level of Milk Production with Reproductive Performance in Dairy Cattle

“…However parity has a large effect on both production and culling, so to compare across parities the best measure of production is 305 day milk yield mature equivalent, or parity should be accounted for in another way. Quist et al [13] showed that projections from test days later in lactation are more accurate than projections in early lactation. Completed 305 day milk yields are a more accurate measure of production but limiting analysis of reproduction to cows with complete lactation records introduces a bias due to exclusion of information from cows removed up to 304 days in milk (DIM) because of low production or lack of reproductive success.…”