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Growth hormone and milking frequency act differently on goat mammary gland in late lactation
- Source :
- Journal of Dairy Science, Journal of Dairy Science, American Dairy Science Association, 2003, 86, pp.509-520
- Publication Year :
- 2003
- Publisher :
- HAL CCSD, 2003.
-
Abstract
- In ruminants, milk yield can be affected by treatment with growth hormone (rbGH) and/or changes in frequency of milking. Frequent milkings encourage the maintenance of lactation, whereas infrequent milkings result in mammary involution. Our objective was to evaluate the influence of rbGH treatment and milking frequency on mammary gland morphology and milk composition. After adaptation to twice-daily milkings, six Saanen goats in late lactation were milked once daily from one udder-half and thrice-daily from the other udder-half. Concurrently, three of the six goats received daily injections of rbGH. After 23 d of treatment, milking frequency significantly affected milk yield (+8% vs. -26% for thrice- vs. once-daily milking). Additionally, treatments of rbGH increased milk yield from thrice-daily milked udder-halves (+19%), but failed to abate the reduction in milk yield from once-daily milked udder-halves (-31%). Mammary glands were heavier in the frequently milked udder-halves and in GH-treated goats. Based on histological and DNA analysis of mammary tissues, it was determined that milking frequency clearly affected epithelial cell numbers and alveolar diameter, whereas rbGH induced a potential cell hypertrophy and only a tendency to increase and/or maintain the mammary cell number. RNA concentration and kappa casein gene expression were not affected by treatments. In udder-halves milked once-daily, low casein:whey protein ratios, high Na+:K+ ratios, and high somatic cell counts (SCC) were indicative of changes in epithelial permeability, which rbGH treatment facilitated. The present data suggest that milking frequency and exogenous treatments of rbGH use different cellular mechanisms to influence mammary gland morphology and milk production.
- Subjects :
- Involution (mathematics)
medicine.medical_specialty
Whey protein
[SDV]Life Sciences [q-bio]
Mammary gland
Gene Expression
Cell Count
Biology
Growth hormone
Milking
03 medical and health sciences
fluids and secretions
Animal science
Mammary Glands, Animal
Internal medicine
Casein
Lactation
Genetics
medicine
Animals
Bovine somatotropin
[INFO]Computer Science [cs]
ComputingMilieux_MISCELLANEOUS
030304 developmental biology
0303 health sciences
Minerals
Goats
0402 animal and dairy science
food and beverages
04 agricultural and veterinary sciences
DNA
Organ Size
Blotting, Northern
Milk Proteins
040201 dairy & animal science
Immunohistochemistry
Lipids
Dairying
medicine.anatomical_structure
Endocrinology
Milk
Growth Hormone
Linear Models
RNA
Animal Science and Zoology
Female
Food Science
Subjects
Details
- Language :
- English
- ISSN :
- 00220302
- Database :
- OpenAIRE
- Journal :
- Journal of Dairy Science, Journal of Dairy Science, American Dairy Science Association, 2003, 86, pp.509-520
- Accession number :
- edsair.doi.dedup.....b5dceaaf3fbef1e51583ea30486c745a