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Effect on scrotal circumference of trucking beef bulls medium and long distances
THERIOGENOLOGY
EFFECT ON SCROTAL CIRCUMFERENCE OF TRUCKING BEEF BULLS MEDIUM AND LONG DISTANCES G. H. Coulter Research Station, Agriculture Canada Lethbridge. Alberta TlJ 4Bl
Received for publication: October 8, 1985 Accepted: ApriZ 16, 1986 ABSTRACT Scrotal circumference (SC) was measured both before and after 2- to 3-yr-old beef bulls were trucked either medium (138 km) or long (565 km) distances. Two SC measurement techniques were used, one recommended by the Society for Theriogenology and the "slip-off" technique. No differences (P > 0.05) were observed between pre--andpost- trucking SC measurements using the Theriogenology technique when bulls were trucked either medium (n = 12; 35.9 + 0.8 vs 35.8 + 0.7 cm) or long (n = 16; 36.5 5 0.5 vs 36.6 + 0.4 cm) distances. However, when the SC of the same bulls was measured using the "slip-off" technique, there was a small, but significant(P < O.O5&reduction in SC for bulls trucked medium (38.0 t 0.7 vs 37.5 + 0.7 cm)and long (38.9 5 0.4 vs 38.6 5 0.4 cm) distances. Bulls having SC at or below the recommended minimum standard reacted no differently to the stress of trucking than did bulls having a SC well above the standard. Errors in measurement technique, severe weather conditions and testicular degeneration over an extended interval are discussed in terms of their potential contribution to the reduction in SC observed by some cattlemen. These data support the use of the SC measurement technique recommended by the Society for Theriogenology because its accuracy is not affected by trucking of bulls. The suggested implementation of an adjustment period between the trucking of beef bulls and measurement of their SC using the Theriogenology technique is not supported. Key words:
beef bulls, scrotal circumference, trucking
Acknowledgements The author would like to thank the Prairie Farm Rehabilitation Administration (PFRA) for making their bulls and facilities available: Mr. Harold Holiday for organizing the experiment;and Mr. Gary Bertram (PFRA Maple Creek Bull Station), Mr. Ken Cobbe (Swift Current - Webb PFRA Community Pasture) and Mr. Ed Steinmacher (Ituna - Bon Accord PFRA Community Pasture) for their assistance in conducting the experiment.
JUNE 1986 VOL. 25 NO. 6
827
THERIOGENOLOGY INTKODUCT
ION
Scrotal circumference (SC) is an important, substantive component (40 of 100 points) of the Society for Theriogenology system for estimating the breeding potential of beef bulls. Factors such as age (1-4, 61, breed (3, 5-71, body weight (1, 2, 71, and season of the year (1, 3) are known to influence the SC trait. Many beef bull shows and sales in western Canada now establish minimum SC standards that bulls must meet or exceed before they are eligible for show or sale. Cattlemen often claim that bulls not attaining the required minimum standard when measured by the culling committee have had a larger SC when measured before being trucked to the show or sale, or upon previous evaluation. These cattlemen often inquire as to the effect of stress of trucking on the SC trait. Although the normal testis is a firm, resilient organ that would not be expected to decrease in size as a result of short-.termtrucking stress, this possibility needed to be examined. This study was designed to determine if the trucking of beef.bulls over medium or long distances resulted in changes in SC.
MATERlALS AND MRTHODS Two groups of beef bulls were used in the experiment. Group 1. trucked the medium distance, was composed of 10 Charolais and two horned Hereford 2-yr-old bulls. Group 2, trucked the longer distance, was composed of 2 Charolais 3-yr-old bulls, 12 Charolais and two polled Hereford 2--yr-oldbulls. All the bulls were owned by the Prairie Farm Rehabilitation Administration (PFRA) of Agriculture Canada. The bulls had been maintained over the winter at the PFRA Bull Station, Maple Creek, Saskatchewan. During the morning of May 9, 1985, the SC of each bull in Groups 1 and 2 was measured and the bulls were loaded immediately into one of two flatbed semi-.trailertrucks. Measurements of SC were taken on bulls restrained in a headgate using two different measurement techniques. In all cases the testes were carefully palpated into the bottom of the scrotum before any measurements were taken. Measurement technique 1 is recommended by the Society for Theriogenology (8) and involves the application of moderate tension to the SC tape placed around the largest circumference of the testes-scrotumwhere the measurement is taken. Measurement technique 2 was the "slip--off"technique (9). The tape was tightened loosely around the neck of the scrotum and then slid slowly downward with the loop enlarging as the circumference increased. The tape fell oEf the scrotum upon reaching the maximum circumference and the measurement was read from the tape. Both techniques were repeated at least once to ensure a consistent result. The same plasticized-cloth scrotal tape was used for both measurement techniques. During the pre-trucking SC measurement period, ambient temperature ranged from 12 to 15°C for both Groups 1 and 2. Group 1 bulls (the medium-distance group) were trucked to the Swift Current --Webb, Saskatchewan PFKA Community Pasture, a distance of 138 km. These bulls were on the truck about 3.5 h before the post-trucking SC measurements began. Ambient temperature during the post-trucking SC measurements was 19OC. Group 2 bulls (the long-distance group) were trucked to the Ituna Bon Accord, Saskatchewan PFRA Community Pasture, a distance of 565 km. JUNE 1986 VOL. 25 NO. 6
THERIOGENOLOGY
Bulls in Group 2 were on the truck about 10.75 h before the post-trucking measurements began. Ambient temperature during the post-trucking SC measurements ranged from 13 to 18OC. All pre- and post-.trucki.ng measurements were taken the same day by the same technician using the 'same measurement techniques and scrotal tape. Significance of differences between means for the SC trait -pre- and Post-trucking were tested using a paired t--test(10). Comparisons were *made within the bull group and within an SC measurement technique only. RESULTS AND DISCUSSION No differences (P > 0.05) were observed in the SC trait when bulls were measured by the technique recommended by the Society for Theriogenology (8) after being trucked over either medium or long distances (Table 1). In contrast, when the "slip-off" SC measurement technique (9) was used, there was a small but significant (P < 0.05) reduction in SC following trucking over either medium or long distances (Table 1). The mean differences (? SE) between pre--and post-trucking SC measurements for bulls measured using the Theriogenology technique and trucked either medium or long distances were 0.08 f 0.28 and 0.09 + 0.15 cm, respectively. The comparable means for bulls measured using the "slip-off" technique were 0.46 f 0.19 and 0.31 ? 0.15 cm,respectively. The cause of the reduction in the SC trait as measured by the “slip-off" technique is unknown. As no tension is applied to the measurement tape when using the "slip-off" technique, the apparent difference in SC due to trucking may, in fact, result from differences in scrotal thickness as influenced by ambient temperature. When SC was measured before trucking, the temperature ranged from 12 to 15"C, while the post-trucking temperatures were 19“C for bulls trucked the medium distance and ranged from 13 to
Table 1. Means (&SE) for the scrotal circumference (SC) trait measured before and after trucking beef bulls medium and long distances SC measurement techniquea
No. bulls
Theriogenology Distance trucked (km) Beforeb Afterb
"Slip--off" Beforeb
Afterb
12
138
35.9 f:0.8
35.8 f 0.7
38.0 + 0.7'
37.5 f o.5c
16
565
36.5 + 0.5
36.6 i:0.4
38.9 _+0.4d
38.6 + 0.3d
'aSee text for description of SC measurement techniques. bSC measurements in cm before and after trucking bulls medium and long distances. cP < 0.05. dF < 0.10. JUNE 1986 VOL. 25 NO. 6
829
THERIOGENOLOGY 18°C for bulls trucked the long distance. The higher temperature at the time of the post-trucking measurements may have caused a thinning of the scrotum that could account for the small but significant reduction in the SC trait. Thus, testicular size may not have decreased even though SC The application of moderate tension to the measurement tape when did. using the Theriogenology technique may take into account the possible effects of temperature on scrotal thickness. The ranges in SC for bulls measured before and after trucking using the Theriogenology technique were 31.0 to 40.0 and 31.0 to 39.0 cm for Group 1 bulls and 34.0 to 39.5 and 34.0 to 39.0 cm for Group 2 bulls, The corresponding ranges in SC when the “slip--off” respectively. technique was used were 33.5 to 42.0 and 33.0 to 41.0 cm for Group 1 and 36.0 to 41.5 and 36.0 to 41.0 cm for Group 2 bulls. There was no indication that bulls having an SC below or at the recommended minimum standard (35.0 and 36.0 cm for 2- and 3-yr-old Charolais and 34.0 cm for 2-yr-old Hereford bulls; Coulter. unpublished) reacted any differently to trucking stress than did bulls having an SC well above the recommended minimum standard. The cause of the apparent reduction in SC reported by some cattlemen between measurements taken at home and those taken by culling committees following the trucking of bulls remains unknown. Possible explanations for the reduction in SC include errors in SC measurement technique when measurements were taken at home and effects of more severe weather conditions during trucking than those tested in the current experiment. Also, if SC measurements are taken several weeks before bulls are trucked to a show or sale, degeneration of the testes may occur in the interim. Beef bulls in the early stages of testicular degeneration could meet or exceed the minimum SC standard on initial measurement yet be well under the minimum SC standard upon being presented to the culling committee owing to continued testicular degeneration. Rapid degeneration of the testes over a short time interval is not uncommon, particularly in fat bulls (11). These data support the use of the SC measurement technique recommended by the Society for Theriogenology as this technique was consistent and was not influenced by trucking bulls over either medium or long distances. Further, when the Theriogenology technique of taking SC measurements is used, the results of this study provide no support for the suggestion that bulls should be allowed a period of adjustment between being trucked and evaluated by a culling committee. REFERENCES 1.
IIIeaSUreNIentS as Coulter. G. H. and Foote, R. H. Bovine testicular indicators of reproductive performance and their relationship to productive traits in cattle: A review. Theriogenology =:297-311 (1979).
2.
Its management and development: Coulter, G. H. Testicular Proc. 8th Tech. Conf. A.I. significance in young beef bulls. Missouri, 1980, pp. 106-111. Reprod., NAAB., Columbia,
3.
Fields, M. J., Burns, W. C. and Warnick, A.C. effects on testicular volume and semen traits J. Anim. Sci. B:l299-1304 (1979).
and
Age. season and breed in young beef bulls.
JUNE 1986 VOL. 25 NO. 6
THERIOGENOLOGY
4.
Vogt. D. W.. Massey, J. W.. Ellersieck, M. R. and Bierschwal. C. Jr. Scrotal circumference adjustment for differences due to age of beef (1984). bulls. J. Am. Vet. Med. Assoc. m:1125-1126
5.
Coulter, G. H. and Keller, D. G. Scrotal circumference of young beef bulls: Relationship to paired testes weight, effect of breed, and predictability. Can. J. Anim. Sci. g:133-139 (1982).
6.
Cates. W. F., Nicholson, H. H.. Crow, G. H. and Janzen, E. D. Testicular development in record of performance bulls. Proc. Ann. Meet. Sot. Theriogenology. Spokane, Washington, 1981. pp. 16-30.
7.
Elmore. R. G.. Bierschwal, C. J. and Youngquist, R. S. Scrotal circumference measurements in 764 beef bulls. Theriogenology 5:485-494 (1976).
8.
Ball, L.. Ott, R. S.. Mortimer, R. G. and Simons, J. C. Manual for Breeding Soundness Examination of Bulls. J. Sot. Theriogenology. Vol. XII,February 1983, pp. 25-30.
9.
Foote, R. H. Research techniques to study reproductive physiology in the male. In: Techniques and procedures in Animal Science Research. Am. sot. Anim. sci, 1969, pp. 81-110.
10.
Steel, R. G. D. and TOrrie. J. H. Principles and Procedures of Statistics, McGraw-Hill Book Company. Inc., Toronto, 1960, pp. 72-78.
11.
Coulter, G. H. and Kozub, G. C. Testicular development, epididymal sperm reserves and seminal quality in two-year-old Hereford and Angus bulls: Effects of two levels of dietary energy. J. Anim. Sci. 2:432-440(1984).
JUNE 1986 VOL. 25 NO. 6
831
EFFECT ON SCROTAL CIRCUMFERENCE OF TRUCKING BEEF BULLS MEDIUM AND LONG DISTANCES G. H. Coulter Research Station, Agriculture Canada Lethbridge. Alberta TlJ 4Bl
Received for publication: October 8, 1985 Accepted: ApriZ 16, 1986 ABSTRACT Scrotal circumference (SC) was measured both before and after 2- to 3-yr-old beef bulls were trucked either medium (138 km) or long (565 km) distances. Two SC measurement techniques were used, one recommended by the Society for Theriogenology and the "slip-off" technique. No differences (P > 0.05) were observed between pre--andpost- trucking SC measurements using the Theriogenology technique when bulls were trucked either medium (n = 12; 35.9 + 0.8 vs 35.8 + 0.7 cm) or long (n = 16; 36.5 5 0.5 vs 36.6 + 0.4 cm) distances. However, when the SC of the same bulls was measured using the "slip-off" technique, there was a small, but significant(P < O.O5&reduction in SC for bulls trucked medium (38.0 t 0.7 vs 37.5 + 0.7 cm)and long (38.9 5 0.4 vs 38.6 5 0.4 cm) distances. Bulls having SC at or below the recommended minimum standard reacted no differently to the stress of trucking than did bulls having a SC well above the standard. Errors in measurement technique, severe weather conditions and testicular degeneration over an extended interval are discussed in terms of their potential contribution to the reduction in SC observed by some cattlemen. These data support the use of the SC measurement technique recommended by the Society for Theriogenology because its accuracy is not affected by trucking of bulls. The suggested implementation of an adjustment period between the trucking of beef bulls and measurement of their SC using the Theriogenology technique is not supported. Key words:
beef bulls, scrotal circumference, trucking
Acknowledgements The author would like to thank the Prairie Farm Rehabilitation Administration (PFRA) for making their bulls and facilities available: Mr. Harold Holiday for organizing the experiment;and Mr. Gary Bertram (PFRA Maple Creek Bull Station), Mr. Ken Cobbe (Swift Current - Webb PFRA Community Pasture) and Mr. Ed Steinmacher (Ituna - Bon Accord PFRA Community Pasture) for their assistance in conducting the experiment.
JUNE 1986 VOL. 25 NO. 6
827
THERIOGENOLOGY INTKODUCT
ION
Scrotal circumference (SC) is an important, substantive component (40 of 100 points) of the Society for Theriogenology system for estimating the breeding potential of beef bulls. Factors such as age (1-4, 61, breed (3, 5-71, body weight (1, 2, 71, and season of the year (1, 3) are known to influence the SC trait. Many beef bull shows and sales in western Canada now establish minimum SC standards that bulls must meet or exceed before they are eligible for show or sale. Cattlemen often claim that bulls not attaining the required minimum standard when measured by the culling committee have had a larger SC when measured before being trucked to the show or sale, or upon previous evaluation. These cattlemen often inquire as to the effect of stress of trucking on the SC trait. Although the normal testis is a firm, resilient organ that would not be expected to decrease in size as a result of short-.termtrucking stress, this possibility needed to be examined. This study was designed to determine if the trucking of beef.bulls over medium or long distances resulted in changes in SC.
MATERlALS AND MRTHODS Two groups of beef bulls were used in the experiment. Group 1. trucked the medium distance, was composed of 10 Charolais and two horned Hereford 2-yr-old bulls. Group 2, trucked the longer distance, was composed of 2 Charolais 3-yr-old bulls, 12 Charolais and two polled Hereford 2--yr-oldbulls. All the bulls were owned by the Prairie Farm Rehabilitation Administration (PFRA) of Agriculture Canada. The bulls had been maintained over the winter at the PFRA Bull Station, Maple Creek, Saskatchewan. During the morning of May 9, 1985, the SC of each bull in Groups 1 and 2 was measured and the bulls were loaded immediately into one of two flatbed semi-.trailertrucks. Measurements of SC were taken on bulls restrained in a headgate using two different measurement techniques. In all cases the testes were carefully palpated into the bottom of the scrotum before any measurements were taken. Measurement technique 1 is recommended by the Society for Theriogenology (8) and involves the application of moderate tension to the SC tape placed around the largest circumference of the testes-scrotumwhere the measurement is taken. Measurement technique 2 was the "slip--off"technique (9). The tape was tightened loosely around the neck of the scrotum and then slid slowly downward with the loop enlarging as the circumference increased. The tape fell oEf the scrotum upon reaching the maximum circumference and the measurement was read from the tape. Both techniques were repeated at least once to ensure a consistent result. The same plasticized-cloth scrotal tape was used for both measurement techniques. During the pre-trucking SC measurement period, ambient temperature ranged from 12 to 15°C for both Groups 1 and 2. Group 1 bulls (the medium-distance group) were trucked to the Swift Current --Webb, Saskatchewan PFKA Community Pasture, a distance of 138 km. These bulls were on the truck about 3.5 h before the post-trucking SC measurements began. Ambient temperature during the post-trucking SC measurements was 19OC. Group 2 bulls (the long-distance group) were trucked to the Ituna Bon Accord, Saskatchewan PFRA Community Pasture, a distance of 565 km. JUNE 1986 VOL. 25 NO. 6
THERIOGENOLOGY
Bulls in Group 2 were on the truck about 10.75 h before the post-trucking measurements began. Ambient temperature during the post-trucking SC measurements ranged from 13 to 18OC. All pre- and post-.trucki.ng measurements were taken the same day by the same technician using the 'same measurement techniques and scrotal tape. Significance of differences between means for the SC trait -pre- and Post-trucking were tested using a paired t--test(10). Comparisons were *made within the bull group and within an SC measurement technique only. RESULTS AND DISCUSSION No differences (P > 0.05) were observed in the SC trait when bulls were measured by the technique recommended by the Society for Theriogenology (8) after being trucked over either medium or long distances (Table 1). In contrast, when the "slip-off" SC measurement technique (9) was used, there was a small but significant (P < 0.05) reduction in SC following trucking over either medium or long distances (Table 1). The mean differences (? SE) between pre--and post-trucking SC measurements for bulls measured using the Theriogenology technique and trucked either medium or long distances were 0.08 f 0.28 and 0.09 + 0.15 cm, respectively. The comparable means for bulls measured using the "slip-off" technique were 0.46 f 0.19 and 0.31 ? 0.15 cm,respectively. The cause of the reduction in the SC trait as measured by the “slip-off" technique is unknown. As no tension is applied to the measurement tape when using the "slip-off" technique, the apparent difference in SC due to trucking may, in fact, result from differences in scrotal thickness as influenced by ambient temperature. When SC was measured before trucking, the temperature ranged from 12 to 15"C, while the post-trucking temperatures were 19“C for bulls trucked the medium distance and ranged from 13 to
Table 1. Means (&SE) for the scrotal circumference (SC) trait measured before and after trucking beef bulls medium and long distances SC measurement techniquea
No. bulls
Theriogenology Distance trucked (km) Beforeb Afterb
"Slip--off" Beforeb
Afterb
12
138
35.9 f:0.8
35.8 f 0.7
38.0 + 0.7'
37.5 f o.5c
16
565
36.5 + 0.5
36.6 i:0.4
38.9 _+0.4d
38.6 + 0.3d
'aSee text for description of SC measurement techniques. bSC measurements in cm before and after trucking bulls medium and long distances. cP < 0.05. dF < 0.10. JUNE 1986 VOL. 25 NO. 6
829
THERIOGENOLOGY 18°C for bulls trucked the long distance. The higher temperature at the time of the post-trucking measurements may have caused a thinning of the scrotum that could account for the small but significant reduction in the SC trait. Thus, testicular size may not have decreased even though SC The application of moderate tension to the measurement tape when did. using the Theriogenology technique may take into account the possible effects of temperature on scrotal thickness. The ranges in SC for bulls measured before and after trucking using the Theriogenology technique were 31.0 to 40.0 and 31.0 to 39.0 cm for Group 1 bulls and 34.0 to 39.5 and 34.0 to 39.0 cm for Group 2 bulls, The corresponding ranges in SC when the “slip--off” respectively. technique was used were 33.5 to 42.0 and 33.0 to 41.0 cm for Group 1 and 36.0 to 41.5 and 36.0 to 41.0 cm for Group 2 bulls. There was no indication that bulls having an SC below or at the recommended minimum standard (35.0 and 36.0 cm for 2- and 3-yr-old Charolais and 34.0 cm for 2-yr-old Hereford bulls; Coulter. unpublished) reacted any differently to trucking stress than did bulls having an SC well above the recommended minimum standard. The cause of the apparent reduction in SC reported by some cattlemen between measurements taken at home and those taken by culling committees following the trucking of bulls remains unknown. Possible explanations for the reduction in SC include errors in SC measurement technique when measurements were taken at home and effects of more severe weather conditions during trucking than those tested in the current experiment. Also, if SC measurements are taken several weeks before bulls are trucked to a show or sale, degeneration of the testes may occur in the interim. Beef bulls in the early stages of testicular degeneration could meet or exceed the minimum SC standard on initial measurement yet be well under the minimum SC standard upon being presented to the culling committee owing to continued testicular degeneration. Rapid degeneration of the testes over a short time interval is not uncommon, particularly in fat bulls (11). These data support the use of the SC measurement technique recommended by the Society for Theriogenology as this technique was consistent and was not influenced by trucking bulls over either medium or long distances. Further, when the Theriogenology technique of taking SC measurements is used, the results of this study provide no support for the suggestion that bulls should be allowed a period of adjustment between being trucked and evaluated by a culling committee. REFERENCES 1.
IIIeaSUreNIentS as Coulter. G. H. and Foote, R. H. Bovine testicular indicators of reproductive performance and their relationship to productive traits in cattle: A review. Theriogenology =:297-311 (1979).
2.
Its management and development: Coulter, G. H. Testicular Proc. 8th Tech. Conf. A.I. significance in young beef bulls. Missouri, 1980, pp. 106-111. Reprod., NAAB., Columbia,
3.
Fields, M. J., Burns, W. C. and Warnick, A.C. effects on testicular volume and semen traits J. Anim. Sci. B:l299-1304 (1979).
and
Age. season and breed in young beef bulls.
JUNE 1986 VOL. 25 NO. 6
THERIOGENOLOGY
4.
Vogt. D. W.. Massey, J. W.. Ellersieck, M. R. and Bierschwal. C. Jr. Scrotal circumference adjustment for differences due to age of beef (1984). bulls. J. Am. Vet. Med. Assoc. m:1125-1126
5.
Coulter, G. H. and Keller, D. G. Scrotal circumference of young beef bulls: Relationship to paired testes weight, effect of breed, and predictability. Can. J. Anim. Sci. g:133-139 (1982).
6.
Cates. W. F., Nicholson, H. H.. Crow, G. H. and Janzen, E. D. Testicular development in record of performance bulls. Proc. Ann. Meet. Sot. Theriogenology. Spokane, Washington, 1981. pp. 16-30.
7.
Elmore. R. G.. Bierschwal, C. J. and Youngquist, R. S. Scrotal circumference measurements in 764 beef bulls. Theriogenology 5:485-494 (1976).
8.
Ball, L.. Ott, R. S.. Mortimer, R. G. and Simons, J. C. Manual for Breeding Soundness Examination of Bulls. J. Sot. Theriogenology. Vol. XII,February 1983, pp. 25-30.
9.
Foote, R. H. Research techniques to study reproductive physiology in the male. In: Techniques and procedures in Animal Science Research. Am. sot. Anim. sci, 1969, pp. 81-110.
10.
Steel, R. G. D. and TOrrie. J. H. Principles and Procedures of Statistics, McGraw-Hill Book Company. Inc., Toronto, 1960, pp. 72-78.
11.
Coulter, G. H. and Kozub, G. C. Testicular development, epididymal sperm reserves and seminal quality in two-year-old Hereford and Angus bulls: Effects of two levels of dietary energy. J. Anim. Sci. 2:432-440(1984).
JUNE 1986 VOL. 25 NO. 6
831