- Email: [email protected]
Use of cow-side progesterone tests to improve reproductive performance of high-producing dairy cows
Theriogenology
42:765-771,
1994
USE OF COW-SIDE PROGESTERONE TESTS TO IMPROVE REPRODUCTIVE PERFORMANCE OF HIGH-PRODUCING DAIRY COWS D.H. Bajemai
‘M.P. HoffmanT.a
T.E. Aitchison3
and S.P. Ford*
‘Agriculture Department Dordt College Sioux Center, IA 51250 USA ‘Department of Animal Science Iowa State University Ames, IA 50011-3150 USA 3Nutrition Professionals, Inc. Hortonville, WI 54944 USA Received for publication: Accepted:
March 29, 1994 August 15, 1994
ABSTRACT This study evaluated the effectiveness of the cow-side ELISA milk progesterone test in improving postpartum reproductive performance in the Dordt College dairy herd. Cows that produced more than 18,500 lb of milk per lactation were assigned to the high production group (40 cows), while cows that produced less than 18,500 lb of milk (42 cows) were assigned to the low production group. Twenty-one cows in the high production group and 19 cows in the low production group received no ELISA testing (untreated controls), while the remaining cows in each group were evaluated by ELISA test every 7 d beginning on Day 27 post partum (treated cows). A sequence of 2 high progesterone tests and 1 low test indicated the cows were cycling normally. Cows that had low milk progesterone levels (~5 ng/ml) for 3 consecutive tests were assumed to have follicular cysts and were treated with 2 ml GnRH (Cystorelin, 50 pg/ml). Cows that had 3 consecutive high tests (>5 ng/ml) were assumed to have persistent corpora lutea (CL) and were treated with 5 ml PGF,o (Lutalyse, 5 mg/ml). In both the high and low production groups, treated cows had higher (P < 0.08) pregnancy rates by Day 210 than the untreated controls (63.2 vs 38.1% and 56.5 vs 42.1%, respectively). The days open were reduced (P c 0.05) for the treated animals by 41.6 d compared with the controls. The treated cows produced a net savings of $70.42 (US) per cow assuming a $3.00 savings/day open. Key words:
ELISA, progesterone,
postpartum
period, ovarian function,
Acknowledgments This is Journal Paper J-l 5181 of the Iowa Agriculture Experiment Station, Ames, IA, Project No. 2273. aCorrespondence and reprint requests.
Copyright 0 1994 Butterworth-Heinemann
dairy cow
and Home Economics
Theriogenology
766 INTRODUCTION
High producing dairy herds often have less than optimal reproductive performance (6,9,10,12). Estrus detection, dysfunctions of the reproductive system, and poor conception rates are frequent problems that reduce performance efficiency, especially at high production levels. A major reason for culling dairy cows is that they do not show visible signs of estrus or that they do not conceive during the postpartum period (7,111. Progesterone, secreted by the corpora lutea (CL), follows a repetitive, cyclic pattern during the estrous cycle of the cow (2). Within 2 to 3 d after estrus (Day 01, the CL begins its growth and progesterone secretion increases. The concentration of progesterone in the blood and milk increases rapidly through Day 10 of the estrous cycle, then plateaus until declining 3 to 4 d before the subsequent estrus, which occurs on =Day 21 (8). Evaluation of progesterone patterns in milk during the postpartum period can thus be utilized as an indicator of ovarian status (I). Management decisions during the postpartum period are a key to an efficient dairy operation, and revolve around efficient reproduction. One key piece of information needed on the reproductive status of a milking herd is detection of anestrus, or irregular-cycling cows, so that the appropriate treatments can be initiated promptly. The ability to determine the concentrations of progesterone in blood has been possible for more than a decade through the use of radioimmunoassay (RlAf techniques. Unfortunately, RIA procedures are expensive and require specialized equipment and highly trained personnel. Further, 3 to 7 d are commonly required to complete the test. The fact that the concentrations of progesterone in milk parallel the concentrations found in the blood have facilitated the development of the enzymelinked immunosorbent assay (ELISA), which utilizes milk as a test material (5). The accuracy of these milk ELISA tests in determining the patterns of ovarian progesterone secretion has compared very favorably with RIA techniques (5). Currently, there are several commercially available ELISA tests on the market (4) which can be performed by on-farm personnel at a relatively low cost. The objective of this study was to evaluate the effectiveness of using a cowside ELISA milk progesterone test to improve reproductive performance by identifying anestrus or irregularly cycling cows, and to treat the cows with follicular cysts or inactive ovaries with GnRH and those with persistent CL with PGF,a to facilitate estrus and conception. MATERIALS
AND METHODS
Dairy Herd Holstein cows in the Dordt College, Sioux Center, Iowa, dairy herd were used to evaluate the effectiveness of using the cow-side ELISA milk progesterone test to The herd had been maintaining a rolling herd improve reproductive performance.
767
Theriogenology
average of more than 20,000 lb of milk and 700 lb of fat. A major challenge was to improve the reproductive performance of the herd. The Dairy Herd Improvement Association (DHIA) reported a calving interval of 475 d, 2.1 services per conception, 105 d to the first breeding and 190 d open. At freshening, all cows beyond their first lactation were assigned to a high (n = 40) production group (above 18,500 lb) and a low (n = 42) production group (below 18,500 lb) based on their projected DHIA records. Milk samples from 19 randomly selected cows in the high production group and from 23 cows in the low production group (i.e., treated cows) were evaluated for progesterone with the ELISA test, which was performed on each cow at 7-d intervals beginning on Day 27 post partum and continuing until each cow was confirmed pregnant by palpation per rectum by a veterinarian, or until culling occurred at Day 210 post partum. The remaining 21 and 19 cows in the high and low production groups, respectively (i.e., control cows), were managed similarly but received no ELISA testing. All cows (control and treated) were observed for estrous activity twice daily throughout the experimental period and were artificially inseminated at each estrus. The only difference between groups was that information from the ELISA test of experimental cows was utilized in the management process. ELISA Test The RPT ELISA progesterone testb was used in the study. The test is designed to use the 5 ng/ml level of progesterone in the milk as the differentiation point between a low and a high test result. All samples were analyzed within 2 h of collection. A 5 ng/ml standard was tested against triplicate milk samples from each cow for calorimetric comparisons. Briefly, the standard and milk samples from each cow were added to assay tubes, incubated for 1 min, and the contents discarded. To each of the 4 tubes, 0.8 ml of horseradish peroxidase conjugate was added, incubated again for 1 min, and the solution discarded. After rinsing the tubes 5 times with tap water, 0.8 ml of enzyme substrate solution + 0.1 ml of developer were added and incubated again for 1 min. Each tube was then read with an electronic scanner at an optical density of 450 nm. An average value for the 3 milk samples from each cow was compared with the standard and classified as high or low. Treatment
Regimens
Two high milk tests and a low test, in any order, during a 21-d interval were considered to be indicative of a normal ovarian cycle. Cows that had high progesterone levels during 3 consecutive 7-d sampling periods were considered to have extended luteal function due to 1 I the presence of a persistent CL or luteal cysts in noninseminated animals or 2) pregnancy in animals previously inseminated at an estrus (these animals received no further treatment as long as all subsequent ELISA
blmmucell Corporation,
Portland,
ME.
768
Theriogenology
tests were high). Noninseminated cows with persistent CL or luteal cysts were treated with 5 ml, im of PGF,(r (Lutalyse,” 5 mg/ml). Cows that exhibited a sequence of 3 consecutive low tests were considered to be noncyclic due to 1) the presence of an unovulated follicular cyst or 2) ovarian inactivity. Cows with 3 consecutive low tests were treated with 2 ml, im GnRH (Cystorelin,d 50flg/ml). After every sequence of 3 consecutive tests, the reproductive status of each cow was reevaluated and the cow was treated accordingly. Regardless of ELISA test results, all cows continued to be tested at 7-d intervals until confirmed pregnant or until 210 d post partum. All cows which were declared open by the veterinarian at 210 d post partum were culled and assigned a value of 210 d open for statistical analysis. Statistical
Analysis
Data (i.e., days open) were analyzed by two-way ANOVA with treatment (control or test), production level (high or low), and the treatment x production level interaction as independent variables (3). Pregnancy rates (%I were evaluated by Chisquare analysis (3). RESULTS AND DISCUSSION Table 1 shows the pregnancy rate between the treated untreated controls for the high and low production groups. Table 1.
Pregnancy controls
rates of dairy cows treated
animals
and the
with PGF,o or GnRH vs the
cows No. of cows pregnant
Treatment categories
High Low High Low
production treated production treated production untreated production untreated
*bMeans
with different
12 13 8 8
superscripts
No. of cows nonpregnant
7 IO 13 11
cows pregnant by group %
pregnant (treated vs untreated) %
63.2 56.5 38.1 42.1
59.5” 40.0b
differ (P < 0.08).
A Chi-square analysis of the data demonstrated no significant difference in the pregnancy rate between the high or low production treated animals and untreated animals. Combining the production groups within a treatment, however, showed the
“Upjohn Company,
Kalamazoo,
dAbbott Company,
Chicago,
IL.
Ml.
769
Theriogenology
pregnancy rate of the treated and the untreated animals to be significantly different (P < 0.08). Thus, providing evidence and support for the efficacy of the ELISA cowside progesterone test in aiding an increase in the reproductive performance of dairy cows. Table 2.
Days open of dairy cows treated
Mean no. of days open
Treatment categories High Low High Low
production production production production
with PGF,a or GnRH vs the controls
by group 118.5 122.1 164.5 159.4
treated treated untreated untreated
“,bMeans + SEM with different
superscripts
_+ * zk f
17.1 17.3 15.0 15.9
Mean no. of days open (treated vs untreated) 120.5
f
17.1”
162.1
+ 15.2b
differ (P c 0.05).
The days open for each production group is presented in Table 2. While the difference between the production groups was not significant, it did approach significance at the P < 0.11. Combining the days open for the high and low groups reveals a difference for the number of days open (P < 0.051, with treated cows exhibiting a 41.6 d decrease in the interval from parturition to conception. This analysis demonstrates that the main difference was due to ELISA testing of the cows, and that differences did not exist mainly due to production levels. To determine the accuracy of the ELISA test, conception dates were established using the information of the dates of insemination and palpation per rectum determination of pregnancy by a veterinarian. The ELISA tests were tabulated after breeding to the point when the animal was declared pregnant by a pregnancy check. All tests should have been high during pregnancy. A low test result was recorded as an incorrect reading. Chi-square analysis showed no significant differences between production groups. Tests demonstrated the ELISA test was accurate 84.4% of the time, which corresponds well with previous reports (I 1. Because our results when the ELISA cow-side was conducted to assess reduce the number of days beyond 90 d open it costs open (4).
showed significant reductions in the number of days open progesterone test was performed, an economic analysis the feasibility of using the ELISA progesterone test to open. An accepted value used in the dairy industry is that the dairyman approximately $3.00 per day for every day
The reduction in days open for the high production group was 46 d and for the low production group it was 37.3 d or an average between the 2 groups of 41.6 d
Theriogenology
770
open. At a cost of $3.00 for every day open beyond 90 d, the reduction open saved $124.80 per treated cow.
of 41.6
d
The average number of ELISA treatments administered per cow every 7 d was 12. The tests had a value of $3.00 per test, yielding a total investment per cow of $36.00. There were 1.16 treatments for ovarian dysfunction per cow, which were valued at $5.50 per treatment or an average cost of $6.38. The labor costs were calculated at $6.00 per hour, and 10 min of time were assigned to each cow for conducting the test for a labor cost of $1 .OO per cow. The total treatment costs were an average of $54.38 per cow. The net return is shown below. Average
savings by reducing the number of days open
ELISA test cost/cow Labor costs . . . . . . Treatment costs/cow. Total . . . Net Savings . . . . . . . . . . The total number of cows resulted in a savings of $2,957.64
. . .
. . . .
$124.80
. . . $36.00 . . . . 12.00 . . . *- 6 38 . . . $54.38 . . . . . . . . . . . . . . . . . . $54.38 . , . . . . . . . . . . . . . . . . . . . . . . . . . $70.42 included in the treatment for the treated animals.
groups was 42,
which
We conclude that the ELISA cow-side progesterone test was easy to use and was relatively inexpensive. The ELISA test aided in identifying cows in estrus, cows with follicular cysts, and cows with luteal cysts. The additional information about the Finally, since ovarian reproductive system helped improve herd management. dysfunctions were quickly identified and treated, the interval from parturition to conception in our study was significantly decreased. REFERENCES 1. 2. 3. 4. 5.
6.
Britt JH. Enhanced reproduction and its economic implications. J Dairy Sci 1985;68: 1585-l 589. Hansel W, Concannor PW, Lukaszewska JH. Corpora lutea of large domestic animals. Biol Reprod 1973;8:222-245. Procedures for the Behavioral Sciences. Experimental Design: Kirk RE. Wadsworth Publishing Co., Belmont, MA, 1968. Nebel RL. Symposium: Cowside tests, on-farm milk progesterone tests. J Dairy Sci 1988;71:1682-1687. Nebel RL, Whitier WD, Cassel BG, Britt JH. Comparison of on-farm and laboratory milk progesterone assays for identifying errors in detection of estrus and diagnosis of pregnancy. J Dairy Sci 1987;70:1471-1476. Olds D, Cooper T, Thrift FA. Relationship between milk yield and fertility in dairy cattle. J Dairy Sci 1979;62: 1140-I 144.
Theriogenology 7.
8. 9. IO. 11. 12.
771
Pelissier CL. Identification of reproductive problems and their economic consequences. In: National Invitational Dairy Reproduction Workshop (Louisville, Kentucky) 1982;pp 9. Pennington JA, Spahr SL, Lodge JR. Early diagnosis of pregnancy in cows by progesterone concentrations in milk. Illinois Res Bull 1977; 19: 1 O-l 1. Shanks RD, Freeman AE, Berber PJ. Relationship of reproductive factors with interval and rate of conception. J Dairy Sci 1979;62:74-84. Spalding RW, Everett RW, Foote RH. Fertility in New York artificially inseminated Holstein herds in dairy herd improvement. J Dairy Sci 1975;58:718-723. Westall RA, Burnside EB, Schaeffer LR. Evaluation of Canadian Holstein-Friesian sires on disposal reasons of their daughters. J Dairy Sci 1982;65:2366-2372. Whitmore HL, Tyler WJ, Casida LE. Effects of early postpartum breeding in dairy cattle. J Anim Sci 1974;38:339-346.
42:765-771,
1994
USE OF COW-SIDE PROGESTERONE TESTS TO IMPROVE REPRODUCTIVE PERFORMANCE OF HIGH-PRODUCING DAIRY COWS D.H. Bajemai
‘M.P. HoffmanT.a
T.E. Aitchison3
and S.P. Ford*
‘Agriculture Department Dordt College Sioux Center, IA 51250 USA ‘Department of Animal Science Iowa State University Ames, IA 50011-3150 USA 3Nutrition Professionals, Inc. Hortonville, WI 54944 USA Received for publication: Accepted:
March 29, 1994 August 15, 1994
ABSTRACT This study evaluated the effectiveness of the cow-side ELISA milk progesterone test in improving postpartum reproductive performance in the Dordt College dairy herd. Cows that produced more than 18,500 lb of milk per lactation were assigned to the high production group (40 cows), while cows that produced less than 18,500 lb of milk (42 cows) were assigned to the low production group. Twenty-one cows in the high production group and 19 cows in the low production group received no ELISA testing (untreated controls), while the remaining cows in each group were evaluated by ELISA test every 7 d beginning on Day 27 post partum (treated cows). A sequence of 2 high progesterone tests and 1 low test indicated the cows were cycling normally. Cows that had low milk progesterone levels (~5 ng/ml) for 3 consecutive tests were assumed to have follicular cysts and were treated with 2 ml GnRH (Cystorelin, 50 pg/ml). Cows that had 3 consecutive high tests (>5 ng/ml) were assumed to have persistent corpora lutea (CL) and were treated with 5 ml PGF,o (Lutalyse, 5 mg/ml). In both the high and low production groups, treated cows had higher (P < 0.08) pregnancy rates by Day 210 than the untreated controls (63.2 vs 38.1% and 56.5 vs 42.1%, respectively). The days open were reduced (P c 0.05) for the treated animals by 41.6 d compared with the controls. The treated cows produced a net savings of $70.42 (US) per cow assuming a $3.00 savings/day open. Key words:
ELISA, progesterone,
postpartum
period, ovarian function,
Acknowledgments This is Journal Paper J-l 5181 of the Iowa Agriculture Experiment Station, Ames, IA, Project No. 2273. aCorrespondence and reprint requests.
Copyright 0 1994 Butterworth-Heinemann
dairy cow
and Home Economics
Theriogenology
766 INTRODUCTION
High producing dairy herds often have less than optimal reproductive performance (6,9,10,12). Estrus detection, dysfunctions of the reproductive system, and poor conception rates are frequent problems that reduce performance efficiency, especially at high production levels. A major reason for culling dairy cows is that they do not show visible signs of estrus or that they do not conceive during the postpartum period (7,111. Progesterone, secreted by the corpora lutea (CL), follows a repetitive, cyclic pattern during the estrous cycle of the cow (2). Within 2 to 3 d after estrus (Day 01, the CL begins its growth and progesterone secretion increases. The concentration of progesterone in the blood and milk increases rapidly through Day 10 of the estrous cycle, then plateaus until declining 3 to 4 d before the subsequent estrus, which occurs on =Day 21 (8). Evaluation of progesterone patterns in milk during the postpartum period can thus be utilized as an indicator of ovarian status (I). Management decisions during the postpartum period are a key to an efficient dairy operation, and revolve around efficient reproduction. One key piece of information needed on the reproductive status of a milking herd is detection of anestrus, or irregular-cycling cows, so that the appropriate treatments can be initiated promptly. The ability to determine the concentrations of progesterone in blood has been possible for more than a decade through the use of radioimmunoassay (RlAf techniques. Unfortunately, RIA procedures are expensive and require specialized equipment and highly trained personnel. Further, 3 to 7 d are commonly required to complete the test. The fact that the concentrations of progesterone in milk parallel the concentrations found in the blood have facilitated the development of the enzymelinked immunosorbent assay (ELISA), which utilizes milk as a test material (5). The accuracy of these milk ELISA tests in determining the patterns of ovarian progesterone secretion has compared very favorably with RIA techniques (5). Currently, there are several commercially available ELISA tests on the market (4) which can be performed by on-farm personnel at a relatively low cost. The objective of this study was to evaluate the effectiveness of using a cowside ELISA milk progesterone test to improve reproductive performance by identifying anestrus or irregularly cycling cows, and to treat the cows with follicular cysts or inactive ovaries with GnRH and those with persistent CL with PGF,a to facilitate estrus and conception. MATERIALS
AND METHODS
Dairy Herd Holstein cows in the Dordt College, Sioux Center, Iowa, dairy herd were used to evaluate the effectiveness of using the cow-side ELISA milk progesterone test to The herd had been maintaining a rolling herd improve reproductive performance.
767
Theriogenology
average of more than 20,000 lb of milk and 700 lb of fat. A major challenge was to improve the reproductive performance of the herd. The Dairy Herd Improvement Association (DHIA) reported a calving interval of 475 d, 2.1 services per conception, 105 d to the first breeding and 190 d open. At freshening, all cows beyond their first lactation were assigned to a high (n = 40) production group (above 18,500 lb) and a low (n = 42) production group (below 18,500 lb) based on their projected DHIA records. Milk samples from 19 randomly selected cows in the high production group and from 23 cows in the low production group (i.e., treated cows) were evaluated for progesterone with the ELISA test, which was performed on each cow at 7-d intervals beginning on Day 27 post partum and continuing until each cow was confirmed pregnant by palpation per rectum by a veterinarian, or until culling occurred at Day 210 post partum. The remaining 21 and 19 cows in the high and low production groups, respectively (i.e., control cows), were managed similarly but received no ELISA testing. All cows (control and treated) were observed for estrous activity twice daily throughout the experimental period and were artificially inseminated at each estrus. The only difference between groups was that information from the ELISA test of experimental cows was utilized in the management process. ELISA Test The RPT ELISA progesterone testb was used in the study. The test is designed to use the 5 ng/ml level of progesterone in the milk as the differentiation point between a low and a high test result. All samples were analyzed within 2 h of collection. A 5 ng/ml standard was tested against triplicate milk samples from each cow for calorimetric comparisons. Briefly, the standard and milk samples from each cow were added to assay tubes, incubated for 1 min, and the contents discarded. To each of the 4 tubes, 0.8 ml of horseradish peroxidase conjugate was added, incubated again for 1 min, and the solution discarded. After rinsing the tubes 5 times with tap water, 0.8 ml of enzyme substrate solution + 0.1 ml of developer were added and incubated again for 1 min. Each tube was then read with an electronic scanner at an optical density of 450 nm. An average value for the 3 milk samples from each cow was compared with the standard and classified as high or low. Treatment
Regimens
Two high milk tests and a low test, in any order, during a 21-d interval were considered to be indicative of a normal ovarian cycle. Cows that had high progesterone levels during 3 consecutive 7-d sampling periods were considered to have extended luteal function due to 1 I the presence of a persistent CL or luteal cysts in noninseminated animals or 2) pregnancy in animals previously inseminated at an estrus (these animals received no further treatment as long as all subsequent ELISA
blmmucell Corporation,
Portland,
ME.
768
Theriogenology
tests were high). Noninseminated cows with persistent CL or luteal cysts were treated with 5 ml, im of PGF,(r (Lutalyse,” 5 mg/ml). Cows that exhibited a sequence of 3 consecutive low tests were considered to be noncyclic due to 1) the presence of an unovulated follicular cyst or 2) ovarian inactivity. Cows with 3 consecutive low tests were treated with 2 ml, im GnRH (Cystorelin,d 50flg/ml). After every sequence of 3 consecutive tests, the reproductive status of each cow was reevaluated and the cow was treated accordingly. Regardless of ELISA test results, all cows continued to be tested at 7-d intervals until confirmed pregnant or until 210 d post partum. All cows which were declared open by the veterinarian at 210 d post partum were culled and assigned a value of 210 d open for statistical analysis. Statistical
Analysis
Data (i.e., days open) were analyzed by two-way ANOVA with treatment (control or test), production level (high or low), and the treatment x production level interaction as independent variables (3). Pregnancy rates (%I were evaluated by Chisquare analysis (3). RESULTS AND DISCUSSION Table 1 shows the pregnancy rate between the treated untreated controls for the high and low production groups. Table 1.
Pregnancy controls
rates of dairy cows treated
animals
and the
with PGF,o or GnRH vs the
cows No. of cows pregnant
Treatment categories
High Low High Low
production treated production treated production untreated production untreated
*bMeans
with different
12 13 8 8
superscripts
No. of cows nonpregnant
7 IO 13 11
cows pregnant by group %
pregnant (treated vs untreated) %
63.2 56.5 38.1 42.1
59.5” 40.0b
differ (P < 0.08).
A Chi-square analysis of the data demonstrated no significant difference in the pregnancy rate between the high or low production treated animals and untreated animals. Combining the production groups within a treatment, however, showed the
“Upjohn Company,
Kalamazoo,
dAbbott Company,
Chicago,
IL.
Ml.
769
Theriogenology
pregnancy rate of the treated and the untreated animals to be significantly different (P < 0.08). Thus, providing evidence and support for the efficacy of the ELISA cowside progesterone test in aiding an increase in the reproductive performance of dairy cows. Table 2.
Days open of dairy cows treated
Mean no. of days open
Treatment categories High Low High Low
production production production production
with PGF,a or GnRH vs the controls
by group 118.5 122.1 164.5 159.4
treated treated untreated untreated
“,bMeans + SEM with different
superscripts
_+ * zk f
17.1 17.3 15.0 15.9
Mean no. of days open (treated vs untreated) 120.5
f
17.1”
162.1
+ 15.2b
differ (P c 0.05).
The days open for each production group is presented in Table 2. While the difference between the production groups was not significant, it did approach significance at the P < 0.11. Combining the days open for the high and low groups reveals a difference for the number of days open (P < 0.051, with treated cows exhibiting a 41.6 d decrease in the interval from parturition to conception. This analysis demonstrates that the main difference was due to ELISA testing of the cows, and that differences did not exist mainly due to production levels. To determine the accuracy of the ELISA test, conception dates were established using the information of the dates of insemination and palpation per rectum determination of pregnancy by a veterinarian. The ELISA tests were tabulated after breeding to the point when the animal was declared pregnant by a pregnancy check. All tests should have been high during pregnancy. A low test result was recorded as an incorrect reading. Chi-square analysis showed no significant differences between production groups. Tests demonstrated the ELISA test was accurate 84.4% of the time, which corresponds well with previous reports (I 1. Because our results when the ELISA cow-side was conducted to assess reduce the number of days beyond 90 d open it costs open (4).
showed significant reductions in the number of days open progesterone test was performed, an economic analysis the feasibility of using the ELISA progesterone test to open. An accepted value used in the dairy industry is that the dairyman approximately $3.00 per day for every day
The reduction in days open for the high production group was 46 d and for the low production group it was 37.3 d or an average between the 2 groups of 41.6 d
Theriogenology
770
open. At a cost of $3.00 for every day open beyond 90 d, the reduction open saved $124.80 per treated cow.
of 41.6
d
The average number of ELISA treatments administered per cow every 7 d was 12. The tests had a value of $3.00 per test, yielding a total investment per cow of $36.00. There were 1.16 treatments for ovarian dysfunction per cow, which were valued at $5.50 per treatment or an average cost of $6.38. The labor costs were calculated at $6.00 per hour, and 10 min of time were assigned to each cow for conducting the test for a labor cost of $1 .OO per cow. The total treatment costs were an average of $54.38 per cow. The net return is shown below. Average
savings by reducing the number of days open
ELISA test cost/cow Labor costs . . . . . . Treatment costs/cow. Total . . . Net Savings . . . . . . . . . . The total number of cows resulted in a savings of $2,957.64
. . .
. . . .
$124.80
. . . $36.00 . . . . 12.00 . . . *- 6 38 . . . $54.38 . . . . . . . . . . . . . . . . . . $54.38 . , . . . . . . . . . . . . . . . . . . . . . . . . . $70.42 included in the treatment for the treated animals.
groups was 42,
which
We conclude that the ELISA cow-side progesterone test was easy to use and was relatively inexpensive. The ELISA test aided in identifying cows in estrus, cows with follicular cysts, and cows with luteal cysts. The additional information about the Finally, since ovarian reproductive system helped improve herd management. dysfunctions were quickly identified and treated, the interval from parturition to conception in our study was significantly decreased. REFERENCES 1. 2. 3. 4. 5.
6.
Britt JH. Enhanced reproduction and its economic implications. J Dairy Sci 1985;68: 1585-l 589. Hansel W, Concannor PW, Lukaszewska JH. Corpora lutea of large domestic animals. Biol Reprod 1973;8:222-245. Procedures for the Behavioral Sciences. Experimental Design: Kirk RE. Wadsworth Publishing Co., Belmont, MA, 1968. Nebel RL. Symposium: Cowside tests, on-farm milk progesterone tests. J Dairy Sci 1988;71:1682-1687. Nebel RL, Whitier WD, Cassel BG, Britt JH. Comparison of on-farm and laboratory milk progesterone assays for identifying errors in detection of estrus and diagnosis of pregnancy. J Dairy Sci 1987;70:1471-1476. Olds D, Cooper T, Thrift FA. Relationship between milk yield and fertility in dairy cattle. J Dairy Sci 1979;62: 1140-I 144.
Theriogenology 7.
8. 9. IO. 11. 12.
771
Pelissier CL. Identification of reproductive problems and their economic consequences. In: National Invitational Dairy Reproduction Workshop (Louisville, Kentucky) 1982;pp 9. Pennington JA, Spahr SL, Lodge JR. Early diagnosis of pregnancy in cows by progesterone concentrations in milk. Illinois Res Bull 1977; 19: 1 O-l 1. Shanks RD, Freeman AE, Berber PJ. Relationship of reproductive factors with interval and rate of conception. J Dairy Sci 1979;62:74-84. Spalding RW, Everett RW, Foote RH. Fertility in New York artificially inseminated Holstein herds in dairy herd improvement. J Dairy Sci 1975;58:718-723. Westall RA, Burnside EB, Schaeffer LR. Evaluation of Canadian Holstein-Friesian sires on disposal reasons of their daughters. J Dairy Sci 1982;65:2366-2372. Whitmore HL, Tyler WJ, Casida LE. Effects of early postpartum breeding in dairy cattle. J Anim Sci 1974;38:339-346.