Changes in Cisternal Udder Compartment Induced by Milking Interval in Dairy Goats Milked Once or Twice Daily

Abstract

Fourteen Murciano-Granadina dairy goats were used to evaluate udder compartments (cisternal and alveolar) and cisternal recoil after an oxytocin (OT) challenge at different milking intervals (8, 16, and 24 h) during wk 7 of lactation. Goats were milked once (1x; n = 7) or twice (2x; n = 7) daily from wk 2 of lactation. Average milk yields for wk 4 and 8 were 1.76 and 2.24 L/d, for goats milked 1x and 2x, respectively. For each half udder, cisternal area was measured by ultrasonography and cisternal milk was measured by machine milking after i.v. injection of an OT receptor blocking agent. Alveolar milk was then obtained after i.v. injection of OT. Regardless of milking frequency, alveolar milk increased from 8 to 16 h after milking, but did not change thereafter. Cisternal area and cisternal milk increased linearly (R2 = 0.96 to 0.99) up to 24 h, indicating continuous milk storage in the cistern at any alveoli filling degree. Cisternal to alveolar ratio increased with milking interval (from 57:43 to 75:25), but differences between milking intervals were significant at 8 h only, at which time goats milked 2x showed a greater ratio (1x = 51:49; 2x = 62:38). Despite extended milking intervals, cisterns of goats milked 1x did not become larger than cisterns of goats milked 2x after 5 wk of treatment. The highest correlation between cisternal area and cisternal milk was detected at 8 h after milking (r = 0.74). Primiparous goats had smaller cisternal areas and less cisternal milk than multiparous goats at all milking intervals. Cisternal recoil was studied in a sample of multiparous goats milked 1x (n = 4) and 2x (n = 4) by scanning cisterns by ultrasonography at 0, 5, 15, and 30 min after an OT challenge for each milking interval. Cisternal area increased after OT injection for the 8- and 16-h milking intervals, but no differences were observed for the 24-h interval. Unlike cows, no changes in cisternal area were observed after OT injection, indicating the absence of cisternal recoil in goats. We conclude that goats show a large cisternal compartment that increases linearly after milking. Nevertheless, cisternal size did not increased after 1x milking, probably because of lesser milk yield. Multiparous goats had larger cisterns than primiparous goats and were able to store more milk in their cisterns at all milking intervals. Because of the high capacity of goat cisterns, no milk return from cistern to alveoli is expected if milking is delayed after milk letdown.

Relationship between udder morphology traits, alveolar and cisternal milk compartments and machine milking performances of dairy camels (Camelus dromedarius)

“…The cisternal milk fraction varied according to species, breed, lactation stage, parity and milking intervals Salama et al, 2004;Castillo et al, 2008). According to Yagil et al (1999), camels do not have a noticeable mammary cistern which is contradicted by our results.…”

Mensurações ultrassonográficas da cisterna da glândula mamária de caprino transgênico

“…Todas as medidas ultrassonográficas foram possíveis de serem realizadas em ambos os animais. Tais medidas já foram verificadas no úbere de ovinos, bovinos e caprinos (Nudda et al, 2000;Ayadi et al, 2003;Salama et al, 2004).…”

“…Apesar disso, os resultados obtidos foram satisfatórios e semelhantes aos observados em outros estudos (Nudda et al, 2000;Ayadi et al, 2003;Salama et al, 2004).…”

“…Estes resultados assemelham-se aos encontrados na literatura (Salama et al, 2004;Wójtowski et al, 2006).…”

The Course of Machine Milking in Small Ruminants

“…In Murciano-Granadina goats, regardless of differing periods between milkings (8, 16 and 24 hours), milk production in the alveolar fraction increased after milking time from 8 to 16 hours, but a longer interval did not result in any increase in milk production. The glandular area index for follicular sinuses (measured by ultrasound) increased with the length of the periods between milkings (from 57 : 43 to 75 : 25), but the difference was significant at an 8-hour interval between milkings (Salama et al, 2004). A single daily milking in goats of this breed moderately reduced milk yield, whereas it did not affect milk composition and udder health.…”