This picture was shot in Mangrota camel fair. This is Brella camel. One can see the the wide and long teats and very visible milk vein. This breed has promising quality of milk production. Very docile and a real milch breed.
There is wide difference among the camel scientists either the milk vein (length and diameter) is correlated to total milk yield or not. Some studies (Ayadi et al. 2013) has revealed that there is strong correlation between the udder morphology and total milk yield. On contrary, Eisa et al (2011) reported from Sudan that there is no correlation between the milk vein and total milk yield.
Beside the opposite point of view, as a practitioner of camel dairy I have the experience of correlation between udder vein and milk yield though it is not that strong interaction. For some camels it is strong correlation while in the others it is nil.
In short, we can say that a prominent and big/wide milk vein if not directly link with the milk yield but it is a real dairy character in camels. Its gives the portrait of the healthy camel at least.
1. EISA, M, ABU-NIKHAILA, and MAJID. 2011. The Relationship Between Udder, Teats and Milk Vein Measurements with Daily Milk Yield in She-Camel (Camelus dromedaries). Online publication; http://nectarforum.com/index.php-The-Relationship-Between-Udder,-Teats-and-Milk-Vein-Measurements-with-Daily-Milk-Yield-in-She-Camel-(Camelus-dromedarius).html
2. Ayadi, Musaad, Samara, Abdelrahman, Alshaikh, Saleh, and Faye. 2013. Relationship between udder morphology traits, alveolar and cisternal milk compartments and machine milking performances of dairy camels (Camelus dromedaries). Online publication; http://revistas.inia.es/index.php/sjar/article/view/4060