In two separate experiments, lactating goats were milked unilaterally thrice daily instead of twice daily for periods of 13 and 37 wk, starting at 2 to 5 wk after parturition. The other gland was milked twice daily throughout. In both experiments thrice-daily milking increased milk yield significantly. In the first experiment, after 37 wk the amounts of RNA and DNA, rate of cell proliferation and activities of several enzymes per cell were greater in the thrice-milked gland (P less than .05). In the second experiment, after 9 or 10 d of thrice-daily milking the activities of several key mammary enzymes per cell measured in biopsy samples had increased in the thrice-milked but not the twice-milked gland. After 13 wk of thrice-daily milking, the DNA content of the glands and the activity per cell of the key enzymes was the same in both glands, showing that the synthetic capacity of the gland was being used more effectively in the treated gland. These results indicate that several mechanisms contributed to the increased milk yield induced by thrice-daily milking.

Summary. Metabolic

We report the development and characterization of compound 22 (MK-5046), a potent, selective small molecule agonist of BRS-3 (bombesin receptor subtype-3). In pharmacological testing using diet-induced obese mice, compound 22 caused mechanism-based, dose-dependent reductions in food intake and body weight.

In order to investigate the nature of the inhibition of milk secretion during a long milking interval, goats were treated in three possible ways: (i) milked twice daily at 08.00 h and 16.00 h or (ii) milked thrice daily at 00.00 h, 08.00 h and 16.00 h, or (iii) milked thrice daily at 00.00 h, 08.00 h and 16.00 h, but at 00.00 h the milk removed was replaced with an equal volume of isosmotic sucrose solution. The latter treatment was carried out in order to subject the gland to a degree of physical distension equivalent to that on treatment (i). On either thrice‐daily milking or thrice‐daily milking with sucrose replacement, milk secretion rate over the 16.00‐08.00 h period was significantly higher (by about 10% in both cases) than on twice‐daily milking. Secretion rates of lactose, milk protein, citrate and calcium during the 00.00‐08.00 h period were similar on either thrice‐daily milking or thrice‐daily milking with sucrose replacement; the secretion rate of fat was significantly higher on thrice‐daily milking with sucrose replacement. Secretion rates of Na+, K+ and Cl‐ were significantly higher on thrice‐daily milking with sucrose replacement. In the case of Na+, the increased Na+ secretion rate was sufficient to create a normal Na+ concentration in the milk/sucrose mixture removed at the next milking. In the cases of K+ and Cl‐, their secretion rates were not sufficient to restore their concentrations to normal by the next milking.(ABSTRACT TRUNCATED AT 250 WORDS)

SUMMARYGoats were milked frequently (at 10.00, 11.30, 13.00 and 14.30 h) between normal morning and afternoon milking, using a catheter to drain the milk stored in the cistern and large ducts of the mammary gland; no increase in the rate of milk secretion occurred. When the same study was repeated but oxytocin was injected to elicit milk ejection and empty the alveoli, the rate ofmilk secretion increased significantly. The stimulatory effect of frequent catheter-milking plus exogenous oxytocin was evident at peak lactation as well as during declining lactation. When milk stored in the mammary gland was diluted with an isosmotic sucrose solution, the rate of milk secretion increased significantly. Again this effect was apparent at all stages of lactation. These results are discussed in relation to the local inhibitor hypothesis on the modulation of milk secretion.