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The role of gluconeogenic precursors and methyl donors in periparturient Holstein dairy cows on milk yield and metabolic profiles.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	The role of gluconeogenic precursors and methyl donors in periparturient Holstein dairy cows on milk yield and metabolic profiles./
作者:	Chung, Yi-Hua.
面頁冊數:	273 p.
附註:	Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 6400.
Contained By:	Dissertation Abstracts International68-10B.
標題:	Agriculture, Animal Culture and Nutrition. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3284915
ISBN:	9780549270621

The role of gluconeogenic precursors and methyl donors in periparturient Holstein dairy cows on milk yield and metabolic profiles.
Chung, Yi-Hua.

The role of gluconeogenic precursors and methyl donors in periparturient Holstein dairy cows on milk yield and metabolic profiles. - 273 p.

Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 6400.

Thesis (Ph.D.)--The Pennsylvania State University, 2007.

The overall aim of this dissertation was to evaluate the efficacy of propylene glycol (PG) and glycerol, as glucogenic precursors, and choline chloride, as a methyl donor, in improving metabolic status and subsequent production performance for Holstein dairy cows during the periparturient period. In the first study, a dry form of PG was supplemented either via top dressing it to the TMR or including it as a part of the total mixed ration (TMR) to 19 multiparous and 18 primiparous Holstein dairy cows immediately after parturition to 21 d after parturition. Propylene glycol fed either as a top dress or as a part of the TMR reduced plasma BHBA concentration and subsequent incidence rate of subclinical ketosis from 39 to 13%. The percent of cows that experienced multiple episodes of subclinical ketosis was also reduced from 53 to 14% during the first 3 wks of lactation. Propylene glycol fed as a top dress tended to increase the rate of milk production. In the second study, an additive effect of PG plus choline chloride was evaluated in 79 multiparous and 41 primiparous Holstein dairy heifers during the transition period (3 wks before to 3 wks after the parturition). Propylene glycol was fed as a dry form product via incorporating it into the TMR, and choline chloride was fed as rumen protected choline (RPC) via top dressing it onto the TMR. An additive effect of RPC plus dry PG was notable in reducing plasma BHBA concentration. Rumen protected choline tended to improve and/or maintain appetite during the transition period. Dairy cows that transition less optimally such as first-calf heifers may benefit from the beneficial additive effect of RPC plus dry PG. In the third study, a 12-h serial blood sampling was conducted to monitor serum insulin and blood metabolite responses to dry PG and RPC from 6 multiparous Holstein dairy cows in early lactation. Dry propylene glycol fed either by top dressing or mixing it into the TMR reduced plasma BHBA concentration which confirmed the lower plasma BHBA concentration observed in the first study when dry PG was top dressed and in the first and second studies when dry PG was incorporated into the TMR. Rumen protected choline stimulated and/or maintained DMI, and this increase in DMI by RPC likely reduced plasma NEFA concentration and subsequently increased milk yield. Concentration of insulin was similar between treatments at around 2 h after feeding. This similarity in the insulin concentration at 2 h after feeding can explain the similar insulin concentrations observed in the first study. The secretory pattern characteristic of insulin reinforces the importance of a serial blood sampling to accurately assess response of insulin to dietary treatment. In the fourth study, the effectiveness of dry PG via top dressing was compared to liquid PG via oral drenching and the effects of dry PG via incorporating it into the TMR in stimulating serum insulin and rumen and blood metabolite responses under a frequent feeding condition were studied in 8 rumen-cannulated multiparous Holstein dairy cows. Propylene glycol shifted rumen fermentation toward a more glucogenic environment without negatively affecting rumen fermentation and rumen N availability. Responses of rumen VFA profiles and blood insulin and glucose concentrations were highly dependent on the amount of PG that was available to the rumen at the time of sampling. Serum insulin and blood and rumen metabolites responded similarly to liquid or dry PG drench indicating that top dressing dry PG is as effective as oral drenching. In the last study, the gluconeogenicity of glycerol as a dry glycerin product was evaluated in 39 multiparous Holstein dairy cows during the first 3 wks of lactation. Glycerol fed as a top dress was glucogenic and tended to enhance gluconeogenesis. This glucogenic effect of glycerol however was too transient to elicit a significant lactational response during the first 3 wks of lactation likely due to the overall good health status of cows transitioning into lactation. Collectively, PG as a dry form product reduced plasma BHBA concentration and subsequent incidence rate of subclinical ketosis through its effect on shifting rumen VFA profiles toward a more glucogenic environment and therefore improving carbohydrate status of the cow. The efficacy of PG was highly dependent on the amount of PG that was available to the rumen. Dry propylene glycol fed as a top dress was as effective as oral liquid PG drenching and incorporating dry PG into the TMR could serve as an alternative to top dressing and drenching in stimulating serum insulin and blood and rumen metabolite responses. Glycerol can enhance gluconeogenesis in cows but its gluconeogenicity appears to be less than PG. Rumen protected choline had the potential to stimulate and/or maintain appetite for cows during the transition period. Rumen protected choline reduced plasma NEFA concentration and was additive to the effect of dry PG in reducing plasma BHBA concentration likely through its effect on feed intake. Co-supplementation of RPC plus dry PG is not recommended based on results obtained in this dissertation.

ISBN: 9780549270621Subjects--Topical Terms:

1017857
Agriculture, Animal Culture and Nutrition.

The role of gluconeogenic precursors and methyl donors in periparturient Holstein dairy cows on milk yield and metabolic profiles.
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502 $a Thesis (Ph.D.)--The Pennsylvania State University, 2007.
520 $a The overall aim of this dissertation was to evaluate the efficacy of propylene glycol (PG) and glycerol, as glucogenic precursors, and choline chloride, as a methyl donor, in improving metabolic status and subsequent production performance for Holstein dairy cows during the periparturient period. In the first study, a dry form of PG was supplemented either via top dressing it to the TMR or including it as a part of the total mixed ration (TMR) to 19 multiparous and 18 primiparous Holstein dairy cows immediately after parturition to 21 d after parturition. Propylene glycol fed either as a top dress or as a part of the TMR reduced plasma BHBA concentration and subsequent incidence rate of subclinical ketosis from 39 to 13%. The percent of cows that experienced multiple episodes of subclinical ketosis was also reduced from 53 to 14% during the first 3 wks of lactation. Propylene glycol fed as a top dress tended to increase the rate of milk production. In the second study, an additive effect of PG plus choline chloride was evaluated in 79 multiparous and 41 primiparous Holstein dairy heifers during the transition period (3 wks before to 3 wks after the parturition). Propylene glycol was fed as a dry form product via incorporating it into the TMR, and choline chloride was fed as rumen protected choline (RPC) via top dressing it onto the TMR. An additive effect of RPC plus dry PG was notable in reducing plasma BHBA concentration. Rumen protected choline tended to improve and/or maintain appetite during the transition period. Dairy cows that transition less optimally such as first-calf heifers may benefit from the beneficial additive effect of RPC plus dry PG. In the third study, a 12-h serial blood sampling was conducted to monitor serum insulin and blood metabolite responses to dry PG and RPC from 6 multiparous Holstein dairy cows in early lactation. Dry propylene glycol fed either by top dressing or mixing it into the TMR reduced plasma BHBA concentration which confirmed the lower plasma BHBA concentration observed in the first study when dry PG was top dressed and in the first and second studies when dry PG was incorporated into the TMR. Rumen protected choline stimulated and/or maintained DMI, and this increase in DMI by RPC likely reduced plasma NEFA concentration and subsequently increased milk yield. Concentration of insulin was similar between treatments at around 2 h after feeding. This similarity in the insulin concentration at 2 h after feeding can explain the similar insulin concentrations observed in the first study. The secretory pattern characteristic of insulin reinforces the importance of a serial blood sampling to accurately assess response of insulin to dietary treatment. In the fourth study, the effectiveness of dry PG via top dressing was compared to liquid PG via oral drenching and the effects of dry PG via incorporating it into the TMR in stimulating serum insulin and rumen and blood metabolite responses under a frequent feeding condition were studied in 8 rumen-cannulated multiparous Holstein dairy cows. Propylene glycol shifted rumen fermentation toward a more glucogenic environment without negatively affecting rumen fermentation and rumen N availability. Responses of rumen VFA profiles and blood insulin and glucose concentrations were highly dependent on the amount of PG that was available to the rumen at the time of sampling. Serum insulin and blood and rumen metabolites responded similarly to liquid or dry PG drench indicating that top dressing dry PG is as effective as oral drenching. In the last study, the gluconeogenicity of glycerol as a dry glycerin product was evaluated in 39 multiparous Holstein dairy cows during the first 3 wks of lactation. Glycerol fed as a top dress was glucogenic and tended to enhance gluconeogenesis. This glucogenic effect of glycerol however was too transient to elicit a significant lactational response during the first 3 wks of lactation likely due to the overall good health status of cows transitioning into lactation. Collectively, PG as a dry form product reduced plasma BHBA concentration and subsequent incidence rate of subclinical ketosis through its effect on shifting rumen VFA profiles toward a more glucogenic environment and therefore improving carbohydrate status of the cow. The efficacy of PG was highly dependent on the amount of PG that was available to the rumen. Dry propylene glycol fed as a top dress was as effective as oral liquid PG drenching and incorporating dry PG into the TMR could serve as an alternative to top dressing and drenching in stimulating serum insulin and blood and rumen metabolite responses. Glycerol can enhance gluconeogenesis in cows but its gluconeogenicity appears to be less than PG. Rumen protected choline had the potential to stimulate and/or maintain appetite for cows during the transition period. Rumen protected choline reduced plasma NEFA concentration and was additive to the effect of dry PG in reducing plasma BHBA concentration likely through its effect on feed intake. Co-supplementation of RPC plus dry PG is not recommended based on results obtained in this dissertation.
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