Influence of low vacuum levels on milking characteristics of sheep, goat and buffalo

Different settings of the operating parameters (pulsator rate, pulsator ratio and vacuum) are used for milking dairy species in different parts of the world. The level of the operating vacuum in machine milking is one of the principal factors which influence the integrity of the tissues and the milk quality. High vacuum levels (>42 kPa) are often used to facilitate the opening of the teat canal by overcoming the biological closing forces whithin the teat sphincter, but can result in severe machine-induced teat tissue damage. In this study characteristics and performances of mechanical milking at low vacuum levels have been investigated in different dairy species. Milking times and milk productions have been obtained from milk emission curves, recorded by electronic milk-meters (LactoCorder®) during the milking at different vacuum levels of sheep, goats and buffaloes. The results of the comparative experiments clearly indicate that a low vacuum level modifies the kinetics of milk emission, the machine-on time and, thus, the throughput of milking system, in all the dairy species considered. Milk yield was satisfactory at any level tested, showing that low vacuums can be adequate to completely empty the udder. Slight differences were found across species concerning the increase in the milking time per head associated with low levels of milking vacuum Our study represents a contribution to encourage the decrease of the working vacuum during mechanical milking, also for those dairy species generally considered hard to be milked, as buffaloes. Milking should be performed applying the lowest vacuum level, compatible with not excessively prolonging milking time, in line with the animal welfare on dairy husbandry

Natural and recombinant bovine somatotropin: immunodetection with a sandwich ELISA

Bovine Somatotropin (bST) is a peptide hormone secreted by the anterior pituitary gland and its recombinant form (rbST) is used for artificially boosting milk yield in cows. Identification of rbST is difficult in that there is little difference from the pituitary bST (pbST). In this work, we further studied the possibility of immunologically discriminating between rbST and pbST. With this purpose, we produced mouse monoclonal antibodies using, as antigen, a peptide mimicking the N-terminus of rbST from Monsanto (rbST-M) conjugated to keyhole limpet haemocyanin (KLH) and polyclonal antibodies in rabbits immunized with the whole bST or rbST-M. Hence, we developed a sandwich ELISA with the obtained antibodies for detection and quantification of bST in serum and compared its performance on the two worldwide commercialized rbSTs: rbST-M and rbST from LG Life Science (rbST-LG). The lowest detection limit of the assay was 0.05 ng/ml for rbST-M, 0.10 ng/ml for rbST-LG and 0.15 ng/ml for pbST. Furthermore, the assay showed the capability to amplify the signal in the presence of rbSTs, recognizing more efficiently rbST-M and rbST-LG than pbST (ECn pbST/ECn rbST: 3 and 1.6 respectively). Its employment for measuring bST levels in sera from bovines administered with rbST LG allowed us to detect exceptional values due to the treatment itself and probably further increased as a consequence of the higher affinity for rbSTs of our monoclonal antibod