[Influence of the number of corpora lutea on the release of luteal oxytocin, the transfer of alveolar milk to the cistern and milk production in the ewe].
This experiment was conducted in 59 Lacaune breed ewes in order to compare milk production and milk distribution between alveolar and cisternal storage after superovulation. After a corpora lutea (CL)-free control period, the ewes were superovulated by different treatments (experimental period) and 5 classes were differentiated according to the number of corpora lutea observed (0, 1, 2, 3 to 6 and > 6 CL respectively (group A (n = 20), B (n = 7), C (n = 14), D (n = 7), E (n = 11)). Our results showed a positive correlation between the number of corpora lutea and the oxytocin and progesterone levels in plasma, total milk production and cisternal volume, and a negative correlation with alveolar volume. The milk production at the evening milking for groups A and E (388.6 and 384.8 ml respectively during the control period) respectively reached 321.7 ml (-17.2%) and 413.4 ml (+7.4%) during the experimental period; ie, a 24.6% difference between these 2 extreme groups. These results could likely be explained by oxytocin levels reaching those obtained during milking and by the effect of milk transfer from the alveolar to the cisternal lumen. Additionally, progesterone could act directly on milk synthesis at the level of the secretory cells.
Labussière
J
J
INRA, laboratoire de la Traite, Rennes, France.
Marnet
P G
PG
Combaud
J F
JF
Beaufils
M
M
de la Chevalerie
F A
FA
D000818:Animals; D002452:Cell Count; D003338:Corpus Luteum / Q000166:cytology / Q000502:physiology*; D015237:Dinoprost / Q000494:pharmacology; D005260:Female; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D010121:Oxytocin / Q000097:blood / Q000378:metabolism*; D011374:Progesterone / Q000097:blood; D012756:Sheep / Q000502:physiology*
D011374:Progesterone; D010121:Oxytocin; D015237:Dinoprost
Influence du nombre de corps jaunes sur la libération d'ocytocine lutéale, le transfert du lait alvéolaire dans la citerne et la production laitière chez la brebis.