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- Title
Effects of rumen protected choline and dry propylene glycol on production performance and blood metabolites of periparturient Holstein dairy cows.
- Authors
Chung, Y.-H.; Girard, I. D.; Cavassini, P.; Varga, G. A.
- Abstract
Effects of supplementing rumen protected choline (RPC; 50% choline as choline chloride) and dry propylene glycol (PG: 65% purity) to periparturient Holstein dairy cows were studied utilizing a 2x2 factorial treatment arrangement. Sixty-three multiparous cows (average lactation number = 2.3 ± 0.2) were blocked according to criteria before entering the trial. Beginning at 20 d (± 0.3d) before the expected calving date, cows were top dressed with 0 or 50g RPC/cow/d. After parturition, half of the cows from each RPC group were additionally supplemented with 250g dry PG/cow/d mixed into the TMR until d 21 postpartum. Tail vein blood was sampled at -21, -14, -8, -5, -3, -1, +2, +7, +14 and +21 d (± 0.2 d) relative to calving. Pre- and postpartum data were analyzed separately as repeated measure using MIXED procedure of SAS. Dry matter intake, as % of body weight, tended to increase with dry PG supplementation (P = .12). Variability in prepartum blood NEFA was reduced for cows supplemented with RPC (P = .11) as they neared parturition. Changes in postpartum blood BHBA (P = .02) and urine ketones (P = .02) were significantly affected by the interaction of RPC and dry PG overtime. Dry PG appeared to reduce blood BHBA (9.4 vs. 7.4 mg/dL for 0 and 250g dry PG without RPC, respectively) but this reduced effect seemed to be blocked by RPC (9.2 vs. 9.2 mg/dL for 0 and 250g dry PG with RPC, respectively). Urine ketone values were highly correlated with blood BHBA. Milk production did not differ across treatments. Milk fat % tended to increase with RPC supplementation (P = .14). Collectively, RPC and dry PG each had influences on blood metabolites via different mechanisms and through interactions with each other. Individual or additive effects of RPC or dry PG did not elicit any production responses likely due to a relatively positive energy balance based on pre and postpartum BHBA and NEFA values.
- Subjects
PROPYLENE glycols; COWS; MILKFAT; CHOLINE; METABOLITES; MILK yield
- Publication
Journal of Animal Science, 2006, Vol 84, p199
- ISSN
0021-8812
- Publication type
Article