Cornell University, Ithaca, New York

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1 DESIGN AND USE OF A MILKING MACHINE FOR SOWS D. A. HARTMAN AND W. G. POND Cornell University, Ithaca, New York IMITED data are available concerning the lactation performance of L swine. The studies to date have been made by weighing the pigs, individually or as a litter, before and after nursing at pre-determined intervals, the gain in weight being accepted as a measure of the amount of milk suckled (Schneider, 1934; Bonsma and Oosthuizen, 1935; Smith, 1959a, 1959b). Few detailed studies have been made of the composition of sow's milk. This is probably because it has been difficult to obtain adequate samples by manual expression. Before Ely and Petersen (1941) demonstrated the use of oxytocin as a method to induce milk let-down in the cow, samples were obtained by quietly removing a nursing pig and milking the vacated teat by hand. The difficulty with this method has been mentioned by nearly all of the early workers (Henry and Woll, 1897; Woll, 1899; Carlyle, 1903; Hughes and Hart, 1934). Milk samples can be obtained by injecting oxytocin into an ear vein and milking by hand (Braude et al., 1947; Bowland et al., 1949), but only a few teats can be milked because of the limited time of milk flow. Milking machines for sows have been developed by Smith et al. (1951) and Lodge (1957a). Smith (1952a, 1952b, 1959a, 1959b), Perrin (1954) and Lodge (1957b) have reported the use of a machine for obtaining milk samples for composition studies, but not for measuring total yield. A milking machine for sows was developed to collect data which could be used to study lactation performance and to determine the factors affecting milk yield and composition. This machine makes it comparatively easy to collect milk separately and simultaneously from all functional glands. Materials and Methods Design o] the Milking Machine. The machine consists of a 2-unit De Laval vacuum pump, two standard De Laval milk pails and pulsators, 1 and two racks each of which holds six 1-pint milk bottles to which the vacuum line and teat cups are attached (figure 1). Fifteen inches of vacuum and a pulsation rate of 70 per minute were used in this study. A standard, 1-in. O.DY rubber tube vacuum line was used to connect the vacuum pump to a pulsator located on each side of the farrowing crate. The double line vacuum tube was approximately 4 ft. long. Five ~-in. O.D. copper T's were spaced 6 inches apart with a 90 degree elbow attached 1 Acknowledgment is made to the De Laval Separator Company, Poughkeepsie, N. Y. for use of their equipment. 20.D. is outside diameter; I.D. is inside diameter. 78O

2 MILKING MACHINE 781 to the end of each vacuum line. Six 36-in. pieces of ~ - i n. I.D. rubber tubing connect the " T " and " L " joints to the stems of the teat cups. This causes pulsation in alternate teat cups. The large vacuum line from the pail lid was connected by a 3~-in. reducer to a line of five 3~-in. O.D. copper T ' s spaced 2.5 inches apart with a 90 degree elbow on the end. These were attached by 3 in. of ~ - i n. I.D. rubber tubing to six ~ - i n. air cocks. Eight inches of rubber tubing were used to connect the air cocks with 3 in. of 3~-in. O.D. leucite tubing which was inserted through a No. 7 rubber stopper fitted into the milk bottle. A Figure 1. A milking machine for sows. second leucite tube was inserted through the rubber stopper and was connected to 36 in. of ~ - i n. rubber tubing which connected to the teat cup. The teat cups were made of 3~-in. I.D. brass tubing 23~ in. long. A copper tube 1.5 in. long and ~ in. I.D. cut at a 35 degree angle was soldered over a hole in the casing which was cut at the same angle. A ring was made of 3/32-in. solid wire, fitted snugly into the topmost part of the casing, and soldered, giving it an I.D. of 9/16 in. Two smaller sizes of teat cups were made by filling in the rings with paste-type aluminum solder, allowing it to harden and then filing it back to 7/16 and 1/2 in. I.D. The fourth and largest size of teat cup ( ~ in. I.D.) was made by using the casing without a ring. The teat cup liner was made of 5~-in. I.D. pure gum flexible rubber tubing with a 1/16-in. thick wall. The liner (4 in. 10ng) was inserted

3 782 HARTMAN AND POND through the casing and folded back snugly over each end. The lower ~ in. of a No. 6 cork stopper was cut off and bored so that a 1 ~-in. length of 5/16-in. O.D. copper tubing fitted snugly through it. A hole 3/64 in. in diameter was bored through one wall of the copper tubing near the cork stopper to allow entrance of the amount of air necessary to keep the line from flooding with milk. The cork stopper was given several coats of Glyptal ~ to insure a good seal when pressed into the bottom of the teat cup. By use of the air cocks any number of teat cups may be used without the loss of vacuum. Since sows may have several teats that are smaller or larger than the others, it is usually necessary to have available teat cups of four different sizes. Milking Procedure. The sow to be milked is driven into a farrowing crate and tied by a rope around her maxilla behind her tusks. The udder is then washed free of dirt. To facilitate the injection of oxytocin, 4 a rubber band may be placed around the base of one ear to make the veins more prominent. Approximately 1.5 ml. of oxytocin is injected into a vein in the ear with a syringe fitted with a 20-gauge needle, and the rubber band is removed. The vacuum pump is started and teat cups are put on immediately. Within 30 seconds, milk let down begins and after 1 to 3 minutes, the rate of flow decreases sharply. As soon as the rate of flow starts to decline, a worker on each side of the sow massages the glands, a procedure which was found to increase the amount of milk by approximately 10%. "['he lactation trends of a Berkshire and Yorkshire sow nursing litters of five and six pigs respectively were estimated by the use of the milking machine described. Milking was done one day weekly during the 1st and 4th through the 9th weeks of lactation. A 2-hour interval during which the pigs were not allowed to nurse preceded each machine milking. Pigs were ear-notched and the teat(s) which they nursed throughout lactation were recorded. The pigs were weighed during the 1st and 4th weeks of lactation to the nearest 5 gm. The sows were under normal herd management. Results and Discussion The data in table 1 were collected on one day during the first and fourth weeks of lactation as previously described. Pigs nursing the teats located more anteriorly tended to make the largest gains. Furthermore, the amount of milk obtained by machine tended to be greater from anteriorly located glands than from posterior glands. There was a positive correlation of r~0.77 between the weight gain of the pigs and the volume of milk oblained by machine milking. Figure 2 indicates the lactation trends of these sows milked by machine during the 1st and 4th through the 9th weeks. Each value represents the :t Apparatus and Maintenance Paint, No. 1201, General ETectric, Chemical Department, Pittsfield, Mass. 4 Armour Purified Oxytc~ic l'rineiple, 20 IT.S.P. Units per ml.

4 1~'[ ILKING lk,iachine 783 TABLE 1. THE YIELD OF MILK OF A BERKSHIRE AND A YORKSHIRE SOW AS MEASURED DURING THE FIRST AND FOURTH WEEK OF LACTATION Total milk obtained Teat by machine Pig no. Gain of pigs = nursed by pig }' at 1:00 p.m." gin. Berkshire sow Yorkshire sow Correlation with rate of gain ml. L1 & RI 663 L2 & L3 286 R2 212 R3 & R4 368 R5 136 R R2 & R3 428 L2 220 L4 381 R4 44 R7 112 = During first four weeks. b LI- -L4=teaL~ on left side, front to rear, respectively. RI--R7=teats on right side, front to rear, respectively. e The combined yield of single nfilkings during the 1st and 4th weeks from teats nursed by pigs listed t~ 1400 "' 1200 I.-..I -- I000 -J 2~ 800 v.--1 2~ 6OO 0 400, I 0 > BERKSHIRE SOW l I I I I I I I [ I TIME, WEEKS Figure 2. Lactation trends of sows as measured by machine milking during the 1st and 4th through the 9th weeks.

5 784 HARTMAN AND POND volume of milk taken after the injection of 1.5 ml. of oxytocin into the ear vein. Some sows rebel against being tied by a rope and it has been necessary to select docile sows for machine milking. Some sows squeal loudly until the injection of oxytocin, but then express grunts as though nursing their pigs. A recording made of pigs squealing at nursing time may be of use in the milking procedure, since on one occasion the sow was coaxed into expressing deep grunts a second time by the workers imitating the sounds made by suckling pigs. A dental syringe with a 30-gauge needle attached has been used on a limited basis to inject xylocaine 5 along an ear vein to numb that area, allowing the oxytocin to be injected easily with a 20-gauge needle. The sows were unaware of being injected with the large needle and little difficultly was experienced in injecting the xylocaine with the 30-gauge needle. Summary A milking machine for sows has been developed which collects milk separately and simultaneously from all functional glands. Its use for measuring the milk yield and for securing adequate samples for composition studies has been indicated on the basis of limited data. Literature Cited Bonsma, F. N. and P. M. Oosthuizen Milk production in Large Black sows. South African J. Animal Sci. 32:360. Bowland, J. P., R. H. Grummer, P. H. Phillips and G. Bohstedt Effect of lactation and ration on the fat and vitamin A level of sow's milk. J. Dairy Sci. 32:22. Braude, R., M. E. Coates, K. M. Henry, S. K. Kon, S. L. Rowland, S. H. Thompson and D. M. Walker A study of the composition of sow's milk. British J. Nutr. 1:64. Carlyle, W. E The food requirement of pigs from birth to maturity. Wisc. Agr. Exp. Stat. Bul. 104:8. Ely, F. and W. E. Petersen Factors involved in the ejection of milk. J. Dairy Sci. 24:211. Henry, W. A. and F. W. Woll On the yield and composition of sow's milk. Wisc. Agr. Exp. Stat. 14th Ann. Report, page 10. Hughes, E. H. and H. G. Hart Production and composition of sow's milk. J. Nutr. 9:311. Lodge, G. A. 1957a. Milking sows by machine. ~[. Agr. Sci. 49:127. Lodge, G. A. 1957b. The utilization of dietary energy by lactating sows. J. Agr. Sci. 49:200. Perrin, D. R The composition of sow's milk during the course of lactation. J. Dairy Res. 21:55. Schneider, K. T The milk production of German high quality breed pigs and the weight development of the piglets during the eight weeks suckling period. Landw. Jahrbucher. Heft 3, 80 Band. 5 Local anesthetic, Astra Pharmaceutical Products, Inc., Worcester, Mass.

6 MILKING MACHINE 785 Smith, D. M., W. G. Whittleston and J. Allen The design and use of a milking machine for sows. J. Dairy Res. 19:31. Smith, D. M. 1952a. The yield and composition of milk of New Zealand Berkshire sows. New Zealand J. Sci. and Tech. 34:65. Smith, D. M. 1952b. Milk production in the sow. Proc. New Zealand Soc. Animal Prod. 12:102. Smith, D. M. 1959a. The yield and composition of milk from sows fed varying proportions of separated milk and concentrates. New Zealand J. Agr. Res. 2: No. 5, Smith, D. M. 1959b. The yield and composition of milk from sows fed on three ration levels. New Zealand J. Agr. Res. 2: No. 5, Woll, F. W The composition of sow's milk. Wisc. Agr. Exp. Stat. 16th Ann. Report, page 267.