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Effect of mating stimuli on LH release in bulls
THERIOGENOLOGY
EFFECT OF MATING STIMULI ON LH RELEASE IN BULLSa R. E. Short, R. D. Randelb and R. A. Bellows Livestock and Range Research Station, U. S. Department of Agriculture and Montana Agricultural Experiment Station, Miles City, MT
59301
Received for Publication: February 5, 1979 Abstract Fourteen crossbred beef bulls were assigned at random to receive one of four sexual stimuli treatments. Treatments consisted of: (1) controls (four bulls), no visual or physical contact with any cows; (2) false mount (two bulls), allowed to mount an estrual cow; (3) mated (four bulls), allowed to mount an estrual cow with intromission and ejaculation; (4) electroejaculated (four bulls), no exposure to cows. Serum from blood samples taken at 15-min intervals from -15 min to 2 hr from sexual stimuli were radioimmunoassayed for luteinizing hormone (LH). Four bulls had elevated levels at the pretreatment bleeding, but none of the stimuli induced or were associated with LH releases. Basal levels of LH were consistent within bulls but varied considerably among bulls. Conclusion is that stimuli associated with mating do not cause a release of LH. Introduction Katongole -et al. (1) reported that sexual stimulation induced an immediate release of luteinizing hormone (LH) in two bulls. Other work would question that conclusion (2, 3) since no release of LH was associated with mating. The following experiment was conducted to further determine what effects sexual stimuli have on LH levels in bulls. Materials and Methods Fourteen crossbred beef bulls (various crosses of Angus, Hereford and Charolais) were assigned at random to receive one of four treatments as follows: (1) controls, no visual or physical contact with any cows; (2) false mount, exposed to estrual cow but only mounting activity allowed with no intromission or ejaculation; (3) mated, exposed to estrual cow including mounting activity, intromission and ejaculation;
a Publication has been approved by the Director of the Montana Agricultural Experiment Station, Journal Series No. 918. b
Present address: Texas A & M University Agricultural Research and 75684. Extension Center, Drawer E, Overton, Texas
MARCH 1979 VOL. 11 NO. 3
273
THERIOGENOLOGY
(4) electroejaculation with no exposure to estrual cows. Blood samples from a tail vessel were taken at 15-min intervals starting 15 min before the sexual stimulus and continuing until 2 hr following the stimulus. Control bulls received no stimuli and were bled simultaneously with bulls that received stimuli except no sample was taken O-5 minutes. These bulls were 2-9 years of age, reasonably gentle and all accustomed to being hand mated and worked in the chutes where blood samples were taken. Serum from these samples was stored (-20°C) and later analyzed for LH by radioimmunoassay as described earlier (4). Results and Discussion LH levels for each of the bulls are shown in table 1. Each bull seemed to have consistent basal levels which varied among bulls from very low (bull no. 1) to fairly high (bull nos. 2 and 11). Bulls 2, 9, 11 and 12 had elevated levels of LH associated mainly with the first bleeding. Only one of these (bull no. 9) received the mating stimulus and even then it was after the LH release. Therefore, there was no indication from these data that these forms of mating stimuli were associated with a release of LH. These findings agree with those of Convey et al. (2) and Gombe ^_. et al (3) but disagree with those of Katongole -et al. (1) who reported results from only two bulls. Sanford -et al. -(5) have also found that sexual stimuli in sheep will not result in an immediate release of LH in rams although repeated stimuli eventually raised LH levels. Gombe -et al. (3) concluded that if sexual stimulation in bulls causes LH release, that release must be very short since they did not detect it by bleeding every 30 minutes. The data reported here discount that possibility since a release was not detected when blood samples were taken at 15-min intervals. Therefore, we would conclude that mating stimuli does not induce an immediate release of LH. The positive effects in the data reported by Katongole -et al. (1) may have occurred by chance since observations were reported from only two bulls. Literature Cited 1.
Katongole, C. B., Naftolin, F. and Short, R. V. 1971. Relationships between blood levels of luteinizing hormone and testosterone in bulls, and the effects of stimulation. J. Endocrinol. 50:457.
2.
Convey, E. M., Pretschneider, E., Hafs, H. D. and Oxender, W. D. 1971. Serum levels of LH, prolactin and growth hormone after ejaculation in bulls. Biol. Reprod. 5:20.
3.
Gombe, S., Hall, W. C., McEntee, K., Hansel, W. and Pickett, B. W. 1973. Regulation of blood levels of LH in bulls: influence of age, breed, sexual stimulation and temporal fluctuations. J. Reprod. Fert. 35:493.
274
MARCH 1979 VOL. 11 NO. 3
THERIOGENOLOGY
4.
Randel, R. D., R. E. Short, D. S. Christensen and R. A. Bellows. 1973. Effects of various mating stimuli on the LH surge and ovulation time following synchronization of estrus in the bovine. .I.Anim. Sci. 37:128.
5.
Sanford, L. M., Palmer, W. M. and Howland, B. E. 1974. Influence of sexual activity on serum levels of LH and testosterone in the ram. Can. J. Anim. Sci. 54:579.
MARCH 1979 VOL. 11 NO. 3
275
0.55 2.36
Mated
Mated
Mated
Electroejaculate
Electroejaculate
Electroejaculate
Electra ejaculate
8
9
10
11
12
13
14 1.41
0.90
3.47
2.67
0.91
0.43
0.04
1.23
False mount
False mount
5
1.78
1.58
Mated
None
7
None
3
4
6.16
0.00
-15
6
None
None
2
Stimulus
0.56
0.90
0.93
1.89
0.78
1.75
0.57
0.71
0.27
1.65
o-5
0.62
0.60
0.26
1.57
0.37
1.34
0.70
0.98
0.21
1.62
1.41
1.25
5.40
0.00
0.33
0.85
0.67
1.45
0.89
1.44
0.56
0.07
0.67
1.65
1.35
1.09
2.57
0.10
0.58
0.57
0.54
1.81
0.74
0.54
0.64
0.57
0.11
1.53
1.13
0.86
2.37
0.00
0.63
0.22
0.54
1.55
0.27
0.94
0.51
0.24
0.77
0.74
0.84
0.47
1.96
0.12
0.22
0.54
0.64
1.28
0.23
0.73
0.51
0.26
0.34
0.81
0.49
0.48
1.10
0.00
0.68
0.29
0.41
1.63
0.59
0.91
1.03
0.76
0.29
0.92
0.58
0.53
1.63
0.00
0.40
0.38
0.49
1.19
0.11
0.29
0.54
1.07
0.12
0.00
0.70
0.00
0.69
0.08
Time of sample in relation to stimulus (min.) 75 90 105 15 30 45 60
LH LEVELS (NG/ML) FOLLOWING MATING STIMULI IN THE BULL
1
Bull no.
TABLE I.
0.35
0.03
0.19
1.45
0.00
0.70
0.46
0.01
0.26
0.36
0.38
0.00
1.06
0.15
120
EFFECT OF MATING STIMULI ON LH RELEASE IN BULLSa R. E. Short, R. D. Randelb and R. A. Bellows Livestock and Range Research Station, U. S. Department of Agriculture and Montana Agricultural Experiment Station, Miles City, MT
59301
Received for Publication: February 5, 1979 Abstract Fourteen crossbred beef bulls were assigned at random to receive one of four sexual stimuli treatments. Treatments consisted of: (1) controls (four bulls), no visual or physical contact with any cows; (2) false mount (two bulls), allowed to mount an estrual cow; (3) mated (four bulls), allowed to mount an estrual cow with intromission and ejaculation; (4) electroejaculated (four bulls), no exposure to cows. Serum from blood samples taken at 15-min intervals from -15 min to 2 hr from sexual stimuli were radioimmunoassayed for luteinizing hormone (LH). Four bulls had elevated levels at the pretreatment bleeding, but none of the stimuli induced or were associated with LH releases. Basal levels of LH were consistent within bulls but varied considerably among bulls. Conclusion is that stimuli associated with mating do not cause a release of LH. Introduction Katongole -et al. (1) reported that sexual stimulation induced an immediate release of luteinizing hormone (LH) in two bulls. Other work would question that conclusion (2, 3) since no release of LH was associated with mating. The following experiment was conducted to further determine what effects sexual stimuli have on LH levels in bulls. Materials and Methods Fourteen crossbred beef bulls (various crosses of Angus, Hereford and Charolais) were assigned at random to receive one of four treatments as follows: (1) controls, no visual or physical contact with any cows; (2) false mount, exposed to estrual cow but only mounting activity allowed with no intromission or ejaculation; (3) mated, exposed to estrual cow including mounting activity, intromission and ejaculation;
a Publication has been approved by the Director of the Montana Agricultural Experiment Station, Journal Series No. 918. b
Present address: Texas A & M University Agricultural Research and 75684. Extension Center, Drawer E, Overton, Texas
MARCH 1979 VOL. 11 NO. 3
273
THERIOGENOLOGY
(4) electroejaculation with no exposure to estrual cows. Blood samples from a tail vessel were taken at 15-min intervals starting 15 min before the sexual stimulus and continuing until 2 hr following the stimulus. Control bulls received no stimuli and were bled simultaneously with bulls that received stimuli except no sample was taken O-5 minutes. These bulls were 2-9 years of age, reasonably gentle and all accustomed to being hand mated and worked in the chutes where blood samples were taken. Serum from these samples was stored (-20°C) and later analyzed for LH by radioimmunoassay as described earlier (4). Results and Discussion LH levels for each of the bulls are shown in table 1. Each bull seemed to have consistent basal levels which varied among bulls from very low (bull no. 1) to fairly high (bull nos. 2 and 11). Bulls 2, 9, 11 and 12 had elevated levels of LH associated mainly with the first bleeding. Only one of these (bull no. 9) received the mating stimulus and even then it was after the LH release. Therefore, there was no indication from these data that these forms of mating stimuli were associated with a release of LH. These findings agree with those of Convey et al. (2) and Gombe ^_. et al (3) but disagree with those of Katongole -et al. (1) who reported results from only two bulls. Sanford -et al. -(5) have also found that sexual stimuli in sheep will not result in an immediate release of LH in rams although repeated stimuli eventually raised LH levels. Gombe -et al. (3) concluded that if sexual stimulation in bulls causes LH release, that release must be very short since they did not detect it by bleeding every 30 minutes. The data reported here discount that possibility since a release was not detected when blood samples were taken at 15-min intervals. Therefore, we would conclude that mating stimuli does not induce an immediate release of LH. The positive effects in the data reported by Katongole -et al. (1) may have occurred by chance since observations were reported from only two bulls. Literature Cited 1.
Katongole, C. B., Naftolin, F. and Short, R. V. 1971. Relationships between blood levels of luteinizing hormone and testosterone in bulls, and the effects of stimulation. J. Endocrinol. 50:457.
2.
Convey, E. M., Pretschneider, E., Hafs, H. D. and Oxender, W. D. 1971. Serum levels of LH, prolactin and growth hormone after ejaculation in bulls. Biol. Reprod. 5:20.
3.
Gombe, S., Hall, W. C., McEntee, K., Hansel, W. and Pickett, B. W. 1973. Regulation of blood levels of LH in bulls: influence of age, breed, sexual stimulation and temporal fluctuations. J. Reprod. Fert. 35:493.
274
MARCH 1979 VOL. 11 NO. 3
THERIOGENOLOGY
4.
Randel, R. D., R. E. Short, D. S. Christensen and R. A. Bellows. 1973. Effects of various mating stimuli on the LH surge and ovulation time following synchronization of estrus in the bovine. .I.Anim. Sci. 37:128.
5.
Sanford, L. M., Palmer, W. M. and Howland, B. E. 1974. Influence of sexual activity on serum levels of LH and testosterone in the ram. Can. J. Anim. Sci. 54:579.
MARCH 1979 VOL. 11 NO. 3
275
0.55 2.36
Mated
Mated
Mated
Electroejaculate
Electroejaculate
Electroejaculate
Electra ejaculate
8
9
10
11
12
13
14 1.41
0.90
3.47
2.67
0.91
0.43
0.04
1.23
False mount
False mount
5
1.78
1.58
Mated
None
7
None
3
4
6.16
0.00
-15
6
None
None
2
Stimulus
0.56
0.90
0.93
1.89
0.78
1.75
0.57
0.71
0.27
1.65
o-5
0.62
0.60
0.26
1.57
0.37
1.34
0.70
0.98
0.21
1.62
1.41
1.25
5.40
0.00
0.33
0.85
0.67
1.45
0.89
1.44
0.56
0.07
0.67
1.65
1.35
1.09
2.57
0.10
0.58
0.57
0.54
1.81
0.74
0.54
0.64
0.57
0.11
1.53
1.13
0.86
2.37
0.00
0.63
0.22
0.54
1.55
0.27
0.94
0.51
0.24
0.77
0.74
0.84
0.47
1.96
0.12
0.22
0.54
0.64
1.28
0.23
0.73
0.51
0.26
0.34
0.81
0.49
0.48
1.10
0.00
0.68
0.29
0.41
1.63
0.59
0.91
1.03
0.76
0.29
0.92
0.58
0.53
1.63
0.00
0.40
0.38
0.49
1.19
0.11
0.29
0.54
1.07
0.12
0.00
0.70
0.00
0.69
0.08
Time of sample in relation to stimulus (min.) 75 90 105 15 30 45 60
LH LEVELS (NG/ML) FOLLOWING MATING STIMULI IN THE BULL
1
Bull no.
TABLE I.
0.35
0.03
0.19
1.45
0.00
0.70
0.46
0.01
0.26
0.36
0.38
0.00
1.06
0.15
120