Bull Fertility Testing Service

New Zealand Journal of Agriculture, Volume 63, Issue 3, 15 September 1941, Page 209

Bull Fertility Testing Service

By

T. A. BLAKE,

Veterinary Research Officer, Ruakura Animal Research Station. iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiaiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiKiiui

RESULTS are now available for the first year’s work in the bull fertility testing service, the initiation of which was described in the September, 1940, issue of the “Journal.” Semen samples were submitted by veterinarians and stock inspectors from 138 bulls, and for seven , of these repeat samples were forwarded to check the result of the first examination. The bulls were classified as follows:- , Good 48 Moderate :.......< 49 Unsatisfactory 21 Bad \ .............. '. 6 Sterile 7 Useless samples .......... 7 Total 138 During the past few months data have been collected from owners which lllBllllllllllllttlgllllllllllllllllllllllllllllllllilllllllllllllllllllllllll

have enabled the performance of 69 of these bulls to be tabulated against their classification by semen examination. The results are shown in the following table,in which only . bulls with data for at least ten services have been included.

Results of the first year’s work have shown that the bulltesting service is of real value in detecting the bull of low fertility. Steps are being taken this year to increase the efficiency of the service, which is available free of cost to all dairy farmers in New Zealand.

“Good” and “Moderate” Bulls

It will be noted that a number of bulls appear in both the' “good” and “moderate” columns whose fertility was below 50 per cent. It should be explained, however, that the performance .of these bulls was reckoned by calculating the percentage of successful services on all cows, including those which remained empty. This, of course, does "not give a true index of the bull’s fertility, as it is not possible for any bull to fertilise a cow whose reproductive organs are in an unsatisfactory condition. . ' Two herds may be quoted in this connection. In one of them, a bull was classed “good,” but only two out of 39 cows held to the first service. The owner, however, reports that he has, had trouble in the herd during the past 20 years. In the other case, samples were examined from three bulls, and all were classed as “good,” yet their performances were only 0, 6, and 16 per cent, respectively. The fact that three bulls all failed in the same herd would appear to indicate that the trouble lay with the cows. It must be emphasised that the bull is not the only factor in producing

a bad calving record, and where an owner is experiencing trouble and the bull is classed as “good” or even “moderate,” steps should be taken to obtain veterinary advice concerning the reproductive efficiency of the cows. The figures 58 and 57 ' considerably underestimate the respective average percentage fertility of the “good” and “moderate” bulls.

“Unsatisfactory” Bulls

Altogether, 21 bulls were classified as “unsatisfactory.” Four of these are shown in the table as having performances of more than 50 per cent. One, however, recorded only 51 per cent. Of the three with performances between 71 and 80 per cent., the sample from one was very unsatisfactory for examination; a second examination of the semen sample from another indicated that it had been graded ' rather harshly, and “moderate” would have been a more accurate assessment; the

third bull, which was 14 years old, served only 12 cows, and it is highly probable that his performances would not have ' been so good had he been asked to serve a full quota. Eight bulls in the table had records of under 50 per cent. Incomplete data are available for three other bulls. It was reported that cows were returning to one; a second was destroyed; the third was said to be giving fair results, and was retained for further trial. No data are available, concerning the other six bulls classed as “unsatisfactory.”

“BcJ” Bulls

Six bulls were classified as “bad.” One bull shown in the table obtained 65 per cent, conceptions from 17 services. The sample submitted was a very few drops of dirty material, and should have been rejected; the second bull in the table was successful in 27 per cent, of services, and the third left no calves. Incomplete data are available for two others, neither of which appears to have got many cows in calf. No data are available for the other bull classified as “bad.”

"Sterile" Bulls

Seven bulls were classified as “sterile.” One of these obtained two conceptions from 27 services. Two others left no calves. Incomplete data are available for three others, none of which was known to have got any cows in calf. No data are' available from the seventh bull. If the diagnosis of “bad” or “sterile” is accepted in the cases for which no data are available, it will be found that at least 19 bulls have been detected with less than 30 per cent, fertility, and four others with less than 50 per cent, fertility.

Collection of Semen

Many very good samples were received from the veterinarians and stock inspectors, but some were too poor for any useful diagnosis. This was. expected, because it is known that the quality of semen is not always constant, especially when dealing with bulls of moderate or poor fertility. Moreover, the very fact that trouble is being experienced in a herd would suggest the probability of a poor sample being obtained. If the semen is watery, the collector has a difficulty in obtaining a representative - sample from the cow, and the examiner also is placed in a difficult position because he does not know whether the sample is a fair one or not. This unfortunate position may be overcome in many instances by the use of the artificial vagina, which is used to collect the whole semen sample uncontaminated by the secretions from the cow, thus enabling the collector and the examiner to know the quality and quantity of the service without any doubt. For this purpose, artificial vaginas are to be placed at the disposal of the officers of the Department of Agriculture in the main dairying centres, and true samples can be obtained where conditions are suitable. These suitable conditions include a bull which is not very nervous or wild, and the use of a quiet cow in season. In many cases it may be necessary to halter or otherwise put restraint on the cows being used, but this can usually be done without great trouble. A dehorning bail with a large gate opening at the side is excellent for taking samples, but the gate must open on the right-hand side of the cow if the collector is right-handed. This method of obtaining semen is usually quick, and enables the collector to. obtain clean and representative samples without interference /to the cow except

in keeping her quiet during the operation.

Two New Methods

This year, two further methods of assessing fertility will be tested on a limited number of bulls. Both of these have been sponsored by workers at the Wisconsin. Agricultural Experimental Station in America. It has been found that in some bulls of low fertility the concentration of ascorbic acid or vitamin C in the blood and semen is lowered, and in these cases intravenous injections of ascorbic acid have ■ resulted in improved fertility. As occasion offers, the ascorbic acid status of infertile bulls will be assessed and if the results appear to warrant it injections will be made in an attempt to alleviate, the condition. The same group of workers have evolved a diluting fluid in which semen will remain alive for prolonged periods, and they suggest that the fertility of the bull can be' assessed by measuring the length of life of the semen when preserved at low temperatures in their diluent. This method, too, will be tested this year on some bulls. It is desired that the bull-testing service be made available to all farmers whose cows are returning or who, for some reason, wish to utilise the service in order to find out, as nearly as possible, what the performance of the bull is likely to be in practice. In one district during the past season some confusion arose through the belief that samples taken at a distance could not arrive at Ruakura in a suitable condition for examination. In this connection it is pleasing to be able to report that some samples taken from as far afield as Dunedin arrived in excellent condition, and correct diagnosis, was made on a number of them.

Submitting Samples

As indicated last year, farmers desiring to have a bull tested should approach the nearest Government veterinarian or stock inspector, who will arrange to collect a semen sample and forward it to Ruakura for examination. Should owners so desire, collections may be made by qualified veterinarians in private practice. If the latter contemplate forwarding samples, it is suggested that they communicate with the writer, who will , forward full particulars concerning the samples which should be submitted for examination. There may be a little trouble in arranging dates for visits of the officers to collect samples from farms situated

a long distance from the centres because of the petrol restrictions, but it is hoped that most farmers who inquire will be attended without undue' delay It will be much appreciated if farmers who make use of this service will be good enough to keep the usual shed sheet up to date so that records may be obtained at the end of the season. The data required are principally: - 1. The number of cows served by each bull. 2. The number holding to the first service. ■ 3. The number holding to the second service. , i

4. Any items of interest relating to the herd. It must again be stressed that the test is not 100 per cent., perfect, but if an artificial vagina is used to collect the samples, a good deal of reliance may be placed on the assessments of fertility, because the material is suitable for examination and is. moreover, a true sample of the semen produced if two services are obtained under suitable conditions. - . Because of the fluctuation in quality of services, I desire to stress the desirability of a second examination before such drastic action as culling is undertaken, unless the history of the animal agrees with the -classification made by the examiner.

Summary

1. Results of the first year’s work have shown that the bull testing service is of value in detecting the bull of low fertility. ) 2. During the year at least 19 bulls were found with less than 30 per cent.

fertility, and a further four with less than 50 per cent, fertility. 3. The bull is not the only factor in sterility, and where trouble is experienced and the bull is diagnosed as good or even moderate, veterinary advice should be sought in regard to the cows. > 4. Steps are being taken this year to increase the efficiency of the service, which is available free of cost to all dairy farmers in New Zealand.

Acknowledgments

Thanks are tendered to Mr. A. H. Ward, Technical Officer, New Zealand Dairy Board, for assistance in tabulating data, to veterinarians and stock inspectors of the Livestock Division for sympathetically co-operating in the collection of samples and the intelligent interpretation of results to owners, and to all dairy farmers who forwarded breeding statistics for use in checking the efficiency of the service.

Performance • - percentages . of- fertile '. ' matings. ■ Good : . ■ ' 100-70 per cent. , . Moderate 70-50 - " ' per cent. Unsatisfactory. 50-30 '. '.. per cent. '•. Bad. ' 30-10 per cent. Sterile. " . 10-0 per cent. 91-100 : 2 . . " > 81-00 .... 5 . . 2 ' 71-80 ■ 55 .. 3 - 61-70 - 6 3 1 . 51-60 ' 5 ' . 2 : . . 1 41-50 2 — 1 '■ 2 . £ - . 31-50 1 ■ ... '- : 2- . - 2 • .-21-30 4 * . 1 1 11-20 r . ' ' I 2 1 - 1-10 - 2 ■ • • 1 1 0- '• 2 1 . 2 :■ 7 : 2. • •• 1. ..... 2 . Total: 33 ' 18 ■ 12 . 3 3 • Average per 58 57 38 31 0.3 cent, fertility. 58 ■ 57 - 38 ■ 31 0.3