EFFECT OF TEMPERATURE OF WASHING WATER ON RATE OF MACHINE MILKING

New Zealand Journal of Agriculture, Volume 78, Issue 5, 16 May 1949, Page 446

EFFECT OF TEMPERATURE OF WASHING WATER ON RATE OF MACHINE MILKING

By 1

W. G. WHITTLESTON.

I, Physical Chemist, Department of Agricul-

ture, Animal Research Station, Ruakura.

K/TUCH has been said and written in favour of the use of warm water in the 1 . ■ shed for speeding up milking. The theory behind the method is based on the fact that the natural stimulus to the cow is the sucking action of the warm, wet mouth of the calf. However, if it is believed that cows can be trained to let their milk down to the conditioned stimuli of other factors connected with milking, such as bailing up and leg-roping, there is no reason to believe that a warm-water wash would necessarily have a good effect.

IN fact, in the well-run shed where the cows are trained to an orderly procedure there is good evidence for the view that even the pulsator of the milking machine is not absolutely necessary for milking, though in this case lack of pulsation would cause cows such discomfort as to disturb the shed routine. The experiments to be described were carried out in a shed in which a systematic routine was enforced. The normal procedure . consisted of bailing up, washing the udder by directing a stream of water on to it, and massaging thoroughly, followed by the taking of a squirt from each teat into a strip cup. The warm and hotwater washing experiments to be described did not have any measureable effects on the way the cows milked out compared with this normal routine. Plan of the Experiments Twelve cows divided into two sets of 6 were used. The first experiment ran for 6 weeks and was divided into 3 periods of 2 weeks each. During the first period one set of cows was

milked by the ordinary method while the others had their udders rubbed vigorously with a rag dipped into water at 95 to 100 degrees F. (“warm” water). Throughout the second period the treatments were reversed, while another reversal in the third period made it the same as the first. The results were measured in two ways. At every milking the weight of milk given and the time taken from the putting on of the cups to the point at which the milk-flow rate had fallen to gib. of milk per minute were recorded automatically. At the afternoon milkings on Mondays, Wednesdays, Fridays, and Sundays milk-flow graphs showing the way the milk was ejected were recorded. These graphs show whether any change occurred in the response of the cow to milking treatment. The straight part of the milk-flow curve or “maximum milkflow rate” was measured in all cases, as this is a factor less influenced by small day-to-day variations in the shed than is the average milk-flow rate obtained by dividing the milk weight by the milking time.

The following figures summarise the results of the experiment:—

Milk weights per cow per milking lb. Normal milking . 9.16 Warm-water wash .. .. 9.17 Milking times Min. Normal milking .. .. .. 5.68 Warm-water wash.. .. .. 5.72 Difference .. .... .. 0.04

The milking rates are obviously the same, while no differences were detected in the “maximum flow rates.” In . other words the use of warm water did not affect the way the cows let down their milk. Because of this negative result and because in the case of a “problem” cow the use of “hot”-water washing had been helpful, a similar experiment was carried out on the same group of cows, but using water at 130 to 150 degrees F. This experiment was carried out over a period of 5 weeks, using weekly periods. and changing the groups over three times, both groups being treated normally during the last week. Again there were no significant differences between the response of the cows to the “hot”-water wash compared with normal methods. The results are summarised in the following figures: — Difference between treatments Mean milk weights .. 8.711 b. 0.171 b. Mean milking times .. 5.0 min. 0.01 min. Avge. milking rate .. 1.811b./min. 0.01b./min. The experiments described were carried out at the Department of Agriculture’s Animal Research Station at Ruakura during December and January. of the 1947-48 season. During the summer the temperature of the normal washing water varies between 65 and 75 degrees F., so that it is not “cold.” However, if really hot water would cause an improvement in the letting down of the milk, the effect should have shown up in the second experiment. The case of a “problem” cow has been mentioned. Due to certain special experiments she had become a “double milker,” giving sometimes half of her milk .as machine strippings. By hot-water washing , this cow was made into a normal milker again. Hence it is apparent that where a cow is not letting down her milk normally hot water can be a help, but in the shed which uses a good routine the normal procedure of a thorough wash with cold water followed by the use of a strip cup would appear to be quite adequate. An examination of the milk-flow curves shows that the cows had always let their milk down when the cups were put on. The results of the experiments described demonstrate that in the Waikato in summer the use, of hot or warm washing water in the well-run shed has no effect on the efficiency of milking. The statistical work on the above experiments was done by Miss J. G. Miller, Department of Agriculture, Wellington.