Bulk tank milk urea nitrogen: seasonal patterns and ...
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| Title | Bulk tank milk urea nitrogen: seasonal patterns and relationship to individual cow milk urea nitrogen values |
| Author(s) | P. Arunvipas, J. VanLeeuwen, I. Dohoo, G. Keefe |
| Journal | Canadian journal of veterinary research = Revue canadienne de recherche veterinaire |
| Date | 2004 |
| Volume | 68 |
| Issue | 3 |
| Start page | 169 |
| End page | 174 |
| Abstract | The objectives of this study were: 1) to determine if bulk tank milk urea nitrogen (BTMUN) and whole herd weighted average of the individual cow MUN levels (WHMUN) were equivalent measurements of herd MUN status; and 2) to determine the seasonal variation in BTMUN concentrations in Prince Edward Island (PEI) dairy herds. For BTMUN-WHMUN correlation testing, bulk tank milk samples from 176 herds were tested for MUN once every 1 to 2 wk between September 1999 and August 2002, as part of routine BTM testing for milk components. During this 3-year period, all herds had all milking cows tested for MUN once a month at the same lab. The WHMUN levels (weighted for milk production) were calculated for each month, and were compared to BTMUN levels using a concordance correlation coefficient (CCC) and a graphic procedure. Tests were only compared if they occurred on the same date, producing a final dataset of 669 comparisons. The BTMUN had good (but not perfect) correlation with WHMUN (CCC = 0.91). This high reliability extended to both the pasture and non-pasture seasons, various milk sampling protocols, and all herd sizes seen in PEI. For evaluating the seasonal variation of BTMUN, the 3 y worth of data (24 803 observations) were divided into 15 seasonal categories, 5 seasons per year (early, mid, and late pasture, and early and late stable). Using linear mixed modelling, significantly (P < 0.05) higher BTMUN values were found during the mid and late pasture seasons of 2000, likely because the precipitation was unusually high during this period, enhancing pasture growth. |
| ISSN | 0830-9000 |
Using APA 6th Edition citation style.
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