Testosterone of estradiol treatment of heifers or freemartins to detect estrus in confined dairy cattle

THERIOGENOLOGY

TESTOSTEROYE OR ESTRADIOL TRLATHEYT OF HEIFERS OR FREEMARTIIS TO DETECT ESTRUS II CObWINED DAIRY CATTLE A.J. Hackett Animal Research Centre Ottawa, Ontario, Canada KlA OC6 Received for publication: January Accepted: August

8, 1986 22, 1986

ABSTRACT Dairy heifers and freemactins were injected with either testosterone or estradiol and then used to detect estrus in mature dairy cows maintained indoors year-round on slatted-concrete floors. During a 15-mo period, 1,026 occurrences of estrus were confirmed from 339 cows. Observations by the herdsmen detected 92% of all occurrences of estrus compared to the heifers (39%) and freemartins (23%). There was great variation among animaLs in their ability to detect estrus. Conception rates were not affected by the method of detection of estrus.

Key

words:

estrus, estradiol. testosterone, heifer, freemartin tUTRODUCTIOU

Failure to detect estrus and have animals bred and pregnant by 60 to 90 d postpartum is a frequent cause of poor breeding performance in North American dairy herds (l-3). As the trend toward larger herds and increased mechanization continues, cows receive less individual attention, which may lead to lowered reproductive performance (4). Dairy cattle facilities at the Animal Research Centre (ARC) in Ottawa, Ontario, Canada provide for year-round housing indoors in a conventional tie-stall (mainly primiparous cows) or a loose-.housing barn (multiparous cows), each with a capacity of 240 cows (5). Only 50% of the cows in the loose-housing barn were observed in estrus at least once between parturition and 55 d postpartum (6). Thus many of the occurrences of estrus were missed and the average number of days open in this barn was 111 (6). In another study carried out in this bat-n, in which cows are on slatted-concrete floors, virtually 100% of all occurrences of estrus that were recorded were detected by two active testosterone- treated females fitted with a chin-ball marker (7). Uore recently, estradiol-treated heifers fitted with chin-ball

lAnima1 Research Centre Contribution No. 1372 Acknowledgement: The author gratefuLly acknowledges the assistance of M.J. Clyde in collecting the data.

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markers were used to detect estrus in this barn and detection of estrus was variable (8). By definition, a freemartin is a genetic female which is a sterile intersex-born twin with a male (9). Freemartins treated with a testosterone propionate-testosterone enanthate combination or estradiol implants have been capable of detecting estrus (10). The objective of this study was to ascertain the efficacy of hormonally treated freemartins for detecting estrus in dairy cattle maintained indoors year-round on slatted-concrete floors. The variability among hormonaLly treated heifers and freemartins to detect estrus was evaluated. The proportion of cows conceiving to an estrus detected by the heifers, freemartins. herdsmen or combination of these methods was also evaluated. UATERTALS AND METHODS During a 15-mo period, three heifers (H) and four freemartins propionatea previously given 200 mg testosterone each (F), intramuscularly (i.m.) everybother day for ten injections foLlowed by 500 mg testosterone enanthate i.m. every 10 d thereafter, were used to detect estrus (8,111. At the time of treatment, the animals weighed 375, 400 and 460 kg (H) and 375. 387, 395 and 568 kg (F), respectively. During the same period. four intact heifers and four given freemartins, each previously B-estradiol-3-benzoatec (E) subcutaneously at a rate of 10 mg per 250 kg body weight weekly, were also used to detect estrus (8). The estradiol was dissolved in ethanol and made up in corn oil to a final concentration of 10 mg per ml. These animals weighed 383, 400, 420 and 472 kg (I) and 375, 430, 487 and 507 kg (F) at the time of treatment, respectively. At the ARC, pregnant cows calve in a maternity barn and are moved into a windowless loose--housing barn within 24 h postpartum. This barn has two wings, each with two pens. At calving, cows are assigned randomly to Pen 1 (Wing A) or Pen 3 (Wing B). When confirmed pregnant or when resident in the pen for about 150 d,they are moved to another pen; those in pen 1 go to Pen 4 (Wing B) and those in Pen 3 go to Pen 2 (Wing A). The aim is to have as many cows as possible with estrous cycle activity (cycling) in Pens 1 and 3. Each pen contains 60 free staLLs and a slatted-concrete floor walk over a liquid manure pit. Estrus was detected in two different ways: by herdsmen and by hormonally treated animals. The criteria used by the herdsmen were standing for other cows, mounted by other cows, mucus discharge or any combinations thereof. At the ARC, the herdsmen work from 0600 to 1800 h daily and no observations are made at night. OccasionaLly only

aTestosterone propionate, K-Line Pharmaceuticals, Downsview, Ontario. bnalogex. E.L. Stickle & Co. Ltd., Brantford, Ontario. C8-estradiol-3-benzoate, Sigma Chemical Company, St. Louis,UO.

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a blood discharge was observed after an occurrence of estrus or estrus was detected by a veterinarian during routine reproductive checks and these were recorded as an occurrence of estrus. These occurrences were listed as "other." Different paint colors in the chin-ball markers were used for the heifers and freemartins. Any well-marked cow was considered to be detected in estrus by the treated animals. The occurrence of estrus was confirmed by subsequent rectal palpation at 4-wk intervals of a corpus luteum, return to estrus in 21 + 4 d or a subsequent pregnancy. Every 3 mo, the hormonally-treated freemartins were assigned to a different pen (Table 1). E-treated Table 1.

Assignment of hormonally treated freemartins to pens by periods Pen

Period 1 2 3 4 5

1

2

3

4

T E T E T

E T E T E

1 E T E T

E T E T E

T = testosterone; E = estradiol Freemartins were moved clockwise each 3 mo. Heifers treated with T were in Pens 2 and 4 and heifers treated with E were in pens 1 and 3. heifers and testosterone-treated heifers (T) were assigned to Pens 1 and 3 (most cows were cycl.ing) and to Pens 2 and 4 (most cows were pregnant) throughout the 15-mo period, respectively. The data were analyzed by Chi-square analyses (12). Three heifers and four freemartins had to be removed because of mastitis, lameness or injury. They were replaced as soon as possible by a similarly treated animal. There was no immediate replacement for one of the T-treated heifers so there were fewer opportunities for detection of estrus in this subclass. RESULTS AND DISCUSSION During the 15-mo period of this study, there were 1,026 confirmed occurrences of estrus among 339 different cows (Table 2). Forty cows calved twice during the 15--mo period. Of the occurrences of estrus. 92% were detected by the herdsman, which was greater than that detected by the treated heifers (39%) and freemartins (23%). Thirty-six occurrences of estrus (5%) were based on other criteria. Twenty cons were considered in estrus because of restlessness or presence of a follicle detected by a veterinarian during routine reproductive examination, 12 had a post-estrus vaginal blood discharge and four were bred without recorded signs. Thus, 3%

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Table 2.

Detection of estrus by hormonally treated animals and herdsmen Number

Method Heifer Freemartin Herdsmen Other

Occurrences

Detected

9908 1026 1026 1026

382 231 946 36b

x 39 23 92 5

aHormonally treated heifers were not present for 36 occurrences of estrus. bTwenty occurrences of estrus were detected by signs other than standing, mounting, mucus discharge or any combination of the three; 12 by post-estrum vaginal blood;and four were bred and no signs recorded.

of the total occurrences of estrus were detected by the hormonally treated animals only. This marginal increase in estrus detection by marker animals might not warrant the time and expense involved. Because the hormonally treated freemartins detected only 23% of the periods of estrus, one might conclude that they are not appropriate for detection of estrus. However, these results confirm the variability of hormonally treated heifers in detection of estrus. Detection rates of individuals are given in Table 3. For heifers, detection rates ranged from 19 to 62% (P(O.05). Reasons for this variation include lack of aggressiveness, overcrowding of animals and injury due to slipping on the slatted-concrete floors. Much of the poorer response among the freemartins (PO.OS) between the hormone treatments T (31%) or E (30%) in detection of estrus (Table 3). Similar to a previous experiment (81, heifers treated with testosterone were superior in detection of estrus to those treated with estrogen, 50 vs 36%. Three hundred and twenty-eight (328) cows were inseminated from one to seven times (Table 4). Overall pregnancy was 67%. Conception rates by service number varied from 0 (7 services) to 38% (1 service). The first-service conception rate was similar to values reported for cows in this barn previously, as was the number of services per conception (1.77) (6).

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Table 3.

Detection of estrus by hormonally treated heifers and freemartins

Hormone treatment Estradiol Testosterone occb DetC % Days Occ Det Daysa

Type of animal

Heifers

1 2 3 4

456 210 200

Subtotal

89 53 15

42 33 4

4Td 62d 27d

157

79

50

456 209 187 33

X2 = 2.36 (WS)

%

394 233 177 29

189 44 57 12

4Td lQe 32f 4ldf

833

300

36

X2 = 27.15 (P(O.01)

Freemartins 1

376

105

26

2Sd

456

365

65

lEd

2 3 4

250 199 87

132 96 78

10 42 20

Ee 4qf 26df

372 67 17

216 33 10

;;

;$: Odef

411

98

24

Subtotal

X2 = 24.83 (P
568

177

31

615

133

22

X2 = 6.20 (FIS) 1448

433

30

aThe number of days a hormonally treated animal was exposed to cows. bThe number of occurrences of estrus detected by any method. cThe number of detections of estrus by an individual hormonally treated animal. d-e*fUeans within a column with different superscripts are different (P < 0.05).

Table 4.

Conception rates

Insemination number

Number Conceived Inseminated

x

1 2 3 4 5 6 7

328 158 76 40 24 11 5

126 55 20 8 8 4 0

38 35 26 20 33 36 0

Total

328

221

67

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The method of detection of estrus did not influence conception rates which ranged from 34 to 100% for single methods or various combinations (Table 5). Table 5.

Estrus detection and conception rates to first service by method of detection

Method of detection Intact heifer (I) Freemartin (F) Herdsmen (HI Other IF IH FH IFH Total

Percent of total no. inseminated

Number Tnseminated Conceived

1.8 0.6 44.8 2.1 0.0 4.3 29.0 17.4

6 2 147

100.0

328

7

0 14 95 57

%

3 2 50 1 0

50 100 34 14

7

43 20

50 45 35

126

38

IF = heifers and freemartins. ZH = heifers and herdsmen FH = freemartins and herdsmen IFH = heifers. freemartins and herdsmen. In conclusion, fceemartins treated with T or E can detect estrus in cows but were not as effective as hormonally treated heifers, which in turn were less effective than the herdsmen. Variation among individual animals in estrus detection was attributed to physical ReSlJltS conditions such as lameness. clearly demonstrate that herdsmen are essential for detection of estrus in a system such as that at the ARC. REFERENCES 1.

Barr, H.L. Influence of estrus detection on days open in dairy (1975). herds. J. Dairy Sci. =:246-247

2.

King, G.J., Hurnik, J.F. and Robertson, H.A. Ovarian function and estrus in dairy cows during early Lactation. J. Anim. Sci. 42:688-692 (1976).

3.

RounsaviLLe, T.R. Oltenacu, P.A., UiLLigan, R.A. and Foote, R.H. EfPects of heat detection, conception rate and culling policy on reproductive performance in dairy herds. J. Dairy Sci. 62:1435-1442 (1979).

4.

Bozworth, R.W.. Ward, G., Call, E.P. and Bonewitz. E.R.

Analysis

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THERIOGENOLOGY

of factors affecting calving intervals of dairy cows. Sci. -55:334-338 (1972).

J. Dairy

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HcAllister, A.J., Batra, T.R., Chesnais, J.P., Darisse, J.P.F., Emsley. J.A.B., Lee, A.J., Nagai, J., Roy, G.L. Vesely, J.A. and Winter, K.A. The National Cooperative Dairy Cattle Breeding Project. Agric. Can. Res. Inst. Tech. Bull. No. 1 (1980).

6.

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Hackett. A.J. and McAllister, A.J. Onset of estrus in dairy cows maintained indoors year-round. J. Dairy Sci. c:1793-1797 (1984).

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Hackett, A.J. and Lin, C.Y. Comparison of females treated with oestradiol or testosterone to detect oestrus in dairy cattle maintained indoors year-round. Anim. Rep. Sci. 9:119-123.

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Harcum, J.B. The %:22-242 (1974).

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Abstr.

10. Greene, W.A.. and Foote, R.H. Hogil, L. Behavioural characteristics of freemartins administered estradiol. estrone. testosterone and dehydrotestosterone . Hot-m. Behav. 1_0:71-84 (1978). 11. Kiser, T.E., Britt. J.H. and Ritchie, H.D. Testosterone treatment of cows for use in detection of estrus. J. Anim. Sci. 44:1030-1035 (1977). 12. Snedecor, G.W. and Cochran, W.C. Statistical Methods Iowa State CoLlege Press, Ames, 1967,~~. 215-219.

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