Supplementation of ruminally inert fat in heat-stressed dairy cows.

Persistent Link:
http://hdl.handle.net/10150/187067
Title:
Supplementation of ruminally inert fat in heat-stressed dairy cows.
Author:
Chan, Shih-Chen
Issue Date:
1995
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Three experiments (two lactation trials and one metabolic trial) were conducted to determine effects of supplemental fat and protein quality or supplemental fat and evaporative cooling on lactational performance and nutrient digestibilities; and to test the effect of supplemental fat and protein quality on ruminal fermentation and nutrient flow to the duodenum in lactating cows. In the first lactation study, milk and milk fat yields, milk fat percentage, and efficiency of feed utilization (FCM/DMI) were increased by the supplementation of 2.5% prilled fatty acids (PFA). Cows fed a fish-blood protein combination (FB) had lower milk yield and DMI than those fed cottonseed meal. In the second lactation study, milk yield, 3.5% FCM, and fat yield were increased by evaporative cooling. Supplementation of 3% PFA rendering dietary of FA to 7.4% appear to be excessive and resulted in only slightly increased (.7 kg) milk yield. Supplementation of PFA, increased efficiency of feed utilization, but decreased FA digestibility. In the third study (metabolic trial), both high quality (HQ) protein and a high level of supplemental fat gave similar positive responses in milk production. Compared to low quality protein (LQ), HQ increased yields of milk, 3.5% FCM, milk protein, milk lactose, and milk SNF. Compared to LQ, concentrations of lysine (Lys) in coccygeal plasma were higher for HQ and leucine was lower. Arteriovenous difference of plasma concentrations of Lys also was higher for HQ than LQ. Supplementation of PFA increased DMI, yields of milk, 3.5% FCM, milk protein, milk lactose, and milk SNF. Cows fed HQ diet had higher concentration of rumen ammonia N and rumen butyrate was increased by the supplemental fat. Concentrations of total VFA, propionate, butyrate, and valerate were increased by supplementation with HQ protein, thus providing more energy for the high milk production. The HQ diet decreased ratio of acetate:propionate, but increased intakes of OM, and CP, particularly in the MF diet. Also, the HQ diet increased total tract digestibility of CP. Digestibilities of ADF, NDF, and FA were not different among treatments.
Type:
text; Dissertation-Reproduction (electronic)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Animal Sciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Huber, J. Tal

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleSupplementation of ruminally inert fat in heat-stressed dairy cows.en_US
dc.creatorChan, Shih-Chenen_US
dc.contributor.authorChan, Shih-Chenen_US
dc.date.issued1995en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThree experiments (two lactation trials and one metabolic trial) were conducted to determine effects of supplemental fat and protein quality or supplemental fat and evaporative cooling on lactational performance and nutrient digestibilities; and to test the effect of supplemental fat and protein quality on ruminal fermentation and nutrient flow to the duodenum in lactating cows. In the first lactation study, milk and milk fat yields, milk fat percentage, and efficiency of feed utilization (FCM/DMI) were increased by the supplementation of 2.5% prilled fatty acids (PFA). Cows fed a fish-blood protein combination (FB) had lower milk yield and DMI than those fed cottonseed meal. In the second lactation study, milk yield, 3.5% FCM, and fat yield were increased by evaporative cooling. Supplementation of 3% PFA rendering dietary of FA to 7.4% appear to be excessive and resulted in only slightly increased (.7 kg) milk yield. Supplementation of PFA, increased efficiency of feed utilization, but decreased FA digestibility. In the third study (metabolic trial), both high quality (HQ) protein and a high level of supplemental fat gave similar positive responses in milk production. Compared to low quality protein (LQ), HQ increased yields of milk, 3.5% FCM, milk protein, milk lactose, and milk SNF. Compared to LQ, concentrations of lysine (Lys) in coccygeal plasma were higher for HQ and leucine was lower. Arteriovenous difference of plasma concentrations of Lys also was higher for HQ than LQ. Supplementation of PFA increased DMI, yields of milk, 3.5% FCM, milk protein, milk lactose, and milk SNF. Cows fed HQ diet had higher concentration of rumen ammonia N and rumen butyrate was increased by the supplemental fat. Concentrations of total VFA, propionate, butyrate, and valerate were increased by supplementation with HQ protein, thus providing more energy for the high milk production. The HQ diet decreased ratio of acetate:propionate, but increased intakes of OM, and CP, particularly in the MF diet. Also, the HQ diet increased total tract digestibility of CP. Digestibilities of ADF, NDF, and FA were not different among treatments.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAnimal Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairHuber, J. Talen_US
dc.contributor.committeememberTheurer, C. Brenten_US
dc.contributor.committeememberAx, Roy L.en_US
dc.contributor.committeememberReid, Bobby L.en_US
dc.contributor.committeememberArmstrong, Dennis Vernen_US
dc.identifier.proquest9531090en_US
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