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Wang H, Yan Z, Wu X, Zhang Y, Wei Y, Zhao X. Using vaginal discharge score (VDS) grading system to evaluate the effect of clinical endometritis on reproductive performance of dairy cows in China. Anim Reprod 2021; 18:e20200228. [PMID: 34122652 PMCID: PMC8189348 DOI: 10.1590/1984-3143-ar2020-0228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Clinical endometritis (CE) is a major cause in affecting the reproductive performance of dairy cows. The objectives of this study were to ascertain the prevalence of CE and to evaluate the effect of CE on reproductive performance in dairy cows using vaginal discharge score (VDS) grading system. 803 dairy cows were examined by vaginoscope with 4-point VDS at 26 ± 3 days in milk (DIM) and classified into six groups: non-endometritis with VDS 0 (control; CON), endometritis with VDS 1 (MEM), non-treated endometritis with VDS 2 (NTME), treated endometritis with VDS 2 (TME), non-treated endometritis with VDS 3 (NTPE), and treated endometritis with VDS 3 (TPE). Cows in TME and TPE groups were treated with 200 mL of 50% dextrose solution by intrauterine infusion. The prevalence of CE was 33% at 26 ± 3 DIM. Binary logistic regression analysis revealed cows in MEM, NTME and NTPE groups had a less likelihood of first artificial insemination (AI) pregnancy than those in CON group (P < 0.05). Kaplan-Meier survival curves for days open were statistically different (P = 0.004). In Cox regression model, cows in NTME and NTPE groups had a reduced pregnancy rate than those in CON group (P < 0.05). The hazard of pregnancy in NTME group was lower than that in TME group (P = 0.044). Similarly, it was lower for the hazard of pregnancy in NTPE group than in TPE group (P = 0.048). Cows in MEM, NTME, and NTPE groups required more services per pregnancy than those in CON group (P < 0.05). In conclusion, CE examined by the VDS grading system impaired reproductive performance, and mild endometritis with VDS 1 should be treated in the early postpartum period to ameliorate fertility in dairy herds.
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Affiliation(s)
- Hongsheng Wang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.,Gansu Key Laboratory of Animal Generational Physiology and Reproductive Regulation, Lanzhou, China
| | - Zuoting Yan
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Xiaohu Wu
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences of Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Yong Zhang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.,Gansu Key Laboratory of Animal Generational Physiology and Reproductive Regulation, Lanzhou, China
| | - Yubing Wei
- The Animal Husbandry and Veterinary Station of Ganzhou County, Zhangye, China
| | - Xingxu Zhao
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.,Gansu Key Laboratory of Animal Generational Physiology and Reproductive Regulation, Lanzhou, China
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Lindley G, Willshire J, Van Winden S. Reproductive Performance and Partial Budget Analysis of a Prostaglandin or a Modified Ovsynch Protocol in Autumn Calving Dairy Herds. Animals (Basel) 2021; 11:ani11041031. [PMID: 33917310 PMCID: PMC8067381 DOI: 10.3390/ani11041031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/14/2021] [Accepted: 03/31/2021] [Indexed: 12/02/2022] Open
Abstract
Simple Summary In autumn calving dairy herds cattle must conceive within a restricted timeframe to maintain the seasonality of calving. Cattle not observed in estrus prior to the mating start date are frequently treated with a single prostaglandin injection even though its relative effectiveness is unknown. The perceived cost of other treatments, such as a modified Ovsynch protocol, may be a reason why they are less favored. This study compares the reproductive and economic outcomes associated with treating cows not observed in estrus prior to breeding with a modified Ovsynch protocol, in comparison to a single prostaglandin injection. The main inputs influencing profitability are identified, and differences in dry-off strategy are considered. From the analyses, cows treated with a modified Ovsynch protocol had a greater likelihood of conception at the beginning of, and throughout, the breeding season. Differences in barren rate and the amount of milk produced were the main variables affecting profitability, the latter strongly influenced by drying-off policy. Farmers and advisors should consider the relative performance of their breeding strategies as well as their own management policies to optimize reproductive and economic performance. Abstract In autumn calving dairy herds, treatment of cattle not observed in estrus prior to the breeding season is common. Routinely, a single prostaglandin or a modified Ovsynch (MOFT) protocol are used—without evidence of their relative effectiveness. This study compares the effects on conception, associated timing, and profitability of administering cows with prostaglandin or MOFT treatment. A hundred and ninety-two Holstein-Friesian cows from three herds without an observed estrus within 28-days before mating start date were randomly treated with d-cloprostenol (PGOD) or an 8-day MOFT protocol. The association of treatment and calving-breeding start-date interval (CBSI) on the risk of conception were investigated. Partial budget, sensitivity analysis, and Monte Carlo simulation was used to assess economic performance, identify critical input variables, and explore the effects of input uncertainties on model output. There was a significant association between MOFT treatment and conception during 21 and 84 days after mating start date, compared to PGOD. MOFT treatment was associated with a mean net benefit of £58.21 (sd £19.42) and £27.29 (sd £17.75) per cow for herds with a fixed or variable dry-off date, respectively. The relative profitability of an MOFT protocol is dependent on its effects on barren rate and herd dry-off strategy.
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Affiliation(s)
- George Lindley
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK;
- Correspondence:
| | - Jim Willshire
- Endell Farm Vets, 49 Endless Street, Salisbury SP1 3UH, UK;
| | - Steven Van Winden
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK;
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Chambers GP, O'Sullivan ML, Compton C. Effect of treatment of phantom cows with a progesterone-based synchrony programme. N Z Vet J 2020; 68:313-323. [PMID: 32192414 DOI: 10.1080/00480169.2020.1745109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Aim: To determine the effect of a progesterone-based synchrony programme on the daily hazard of conception and the probability of being pregnant at the end of the seasonal mating period in cows not observed in oestrus within 35-49 days of insemination and that were diagnosed non-pregnant (phantom cows) on seasonally calving New Zealand dairy farms. Secondary aims were to determine the prevalence of phantom cows and estimate the proportion of phantom cows with a functional corpus luteum (CL) at enrolment. Methods: Phantom cows from 14 New Zealand commercial dairy farms were enrolled in a randomised, controlled trial. Cows that were artificially inseminated ≤14 days after mating start date and were not subsequently detected in oestrus, were presented for pregnancy diagnosis approximately 49 days after mating start date. Non-pregnant cows were diagnosed as phantom cows and randomly allocated to treatment and control groups. A milk sample was collected for progesterone assay to determine the presence of a functional CL. Treatment consisted of an injection of buserelin and insertion of an intravaginal device containing progesterone on Day 0, injections of dinoprost and equine chorionic gonadotrophin, and removal of the intravaginal device on Day 7, injection of buserelin on Day 9, and fixed time artificial insemination on Day 10. Treatment group cows were then mixed with bulls for the remainder of the seasonal mating period. Cows allocated to the control group were mated naturally by bulls. Statistical models were constructed to determine the effect of treatment on the daily hazard of conception and the probability of being pregnant at the end of the seasonal mating period. Results: A total of 378/4,214 (9.0%) cows presented for pregnancy diagnosis were diagnosed as phantom cows. A functional CL was diagnosed in 257/362 (71.0%) phantom cows. Median predicted enrolment to conception intervals were 33 (95% CI = 30-45) and 30 (95% CI = 28-33) days, for cows in the control and treatment groups, respectively. The odds of being pregnant at the end of mating were 1.70 (95% CI = 1.34-2.17) times greater for treated phantom cows than untreated phantom cows. Estimated marginal mean proportion pregnant at mating end date were 59.5 (95% CI = 47.9-70.1)% and 71.5 (95% CI = 62.6-79.0)% for control and treatment group cows, respectively. Conclusions: Treatment with a progesterone-based synchrony programme significantly increased the probability of phantom cows being pregnant at the end of the seasonal mating period.
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Affiliation(s)
- G P Chambers
- Zoetis New Zealand Limited, Auckland, New Zealand
| | | | - Cwr Compton
- EpiCentre, School of Veterinary Science, Massey University, Palmerston North, New Zealand
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Bates AJ, Saldias B. A comparison of machine learning and logistic regression in modelling the association of body condition score and submission rate. Prev Vet Med 2019; 171:104765. [PMID: 31499454 DOI: 10.1016/j.prevetmed.2019.104765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 08/09/2019] [Accepted: 08/30/2019] [Indexed: 10/26/2022]
Abstract
The effect of body condition score (BCS) on reproductive outcomes is complex, dynamic and non-linear with interaction and confounding. The flexibility inherent in machine learning algorithms makes them attractive for analysing complex data. This study was designed to compare the ability of a range of machine learning techniques in estimating the probability of service within 21 days of the planned start of mating. We hypothesised that if there were complex and unknown interactions or non-linearity in the data, some machine learning algorithms would result in superior model performance compared to regression models. For a period of six months from the planned start of calving, BCS was visually assessed once a month for 6127 cows on 8 commercial New Zealand dairy farms by a trained veterinarian using the DairyNZ 10-point range for every cow in the herd. Cow, lactation and reproductive data was extracted from the national herd database. This data was used to predict probability of service within 21 days of planned start of mating (PSM) using mixed multivariable logistic regression and decision tree, k-nearest neighbour, random forest and neural network analysis. Models were adjusted for herd, cow age, breed, days in milk, BCS at calving, BCS change between calving and mating, BCS change after mating, volume adjusted milk protein and fat concentration pre-mating. Models were constructed on a training data set using 10-fold cross validation repeated 10 times and evaluated on a test data set using discrimination and calibration techniques. In all models, days calved at PSM was the most important variable for predicting submission rate, followed by BCS at PSM. Factors associated with an increased probability of insemination were calving at a BCS of 5.0, losing less BCS after calving, having a higher BCS at nadir, losing BCS rapidly after calving, nadir occurring before PSM and calving early. All the models except for the decision tree had an area under the receiver operating characteristic curve (AUC) in the range 0.68-0.73 indicating good overall discriminatory power, but calibration analysis suggested all models were better at predicting cows that got inseminated than correctly identifying animals that did not get inseminated. Overall, the machine learning techniques were no better than a generalised logistic regression model. These results highlight the importance of BCS targets at calving and indicate BCS loss, milk characteristics and days calves may be useful indicators identifying cows at risk of poor reproductive outcomes.
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Affiliation(s)
- A J Bates
- Vetlife Scientific, 1, Waitohi-Temuka Road, Temuka 7920, New Zealand.
| | - B Saldias
- Centre for Dairy Excellence, 20, Wilson Street, Geraldine 7930, New Zealand
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Okawa H, Fujikura A, Wijayagunawardane MMP, Vos PLAM, Taniguchi M, Takagi M. Effect of diagnosis and treatment of clinical endometritis based on vaginal discharge score grading system in postpartum Holstein cows. J Vet Med Sci 2017; 79:1545-1551. [PMID: 28740032 PMCID: PMC5627325 DOI: 10.1292/jvms.16-0593] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In this study, the prevalence, effectiveness of diagnosis, and treatment based on vaginal discharge score (VDS) of clinical endometritis in cattle were evaluated. To detect clinical endometritis and classify its severity,
vaginoscopy was performed during 21 to 60 days postpartum in 164 Holstein cows consisting of 229 lactations. Groups were defined using the 4-point VDS scale. Study groups included the following: non-endometritis (VDS=0; no/clear
mucus; NEM group; n=168); mild endometritis, no treatment (VDS=1; mucus containing flecks of white/off-white pus; NTR group; n=30); and severe endometritis, treated with PGF2α (VDS≥2; discharge containing <50% pus; and VDS=3;
discharge containing >50% pus, and fluid or uterine horn asymmetry; TEM group; n=31). Cows treated with PGF2α that did not recover (VDS≥1, n=5) received intrauterine procaine penicillin and streptomycin. Prevalence of clinical
endometritis (VDS≥1) was 26.6%. The NTR group required significantly more artificial inseminations per pregnancy than NEM and TEM groups (2.8 ± 1.8 vs 2.0 ± 1.3, 1.9 ± 0.8, P<0.05). In survival analysis, the
proportion of non-pregnant cows was higher in the NTR group compared to the NEM (P=0.012) and TEM (P=0.076) groups. In the TEM group, calving to first artificial insemination interval tended to be
higher in cows treated 41 to 60 days postpartum than cows treated 29 to 40 days postpartum (97.2 ± 27.1 vs 74.4 ± 19.7, P=0.084). Our study suggests that cows with VDS=1 may require treatment to recover fertility.
Diagnosis and treatment of clinical endometritis based on a VDS grading system may improve dairy herd reproductive performance.
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Affiliation(s)
- Hiroaki Okawa
- United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi 753-8515, Japan.,Fukuoka Prefecture Dairy Cooperative Association, Fukuoka 819-0373, Japan
| | - Atsushi Fujikura
- Fukuoka Prefecture Dairy Cooperative Association, Fukuoka 819-0373, Japan
| | | | - Peter L A M Vos
- Department of Farm Animal Health, Utrecht University, Yalelaan 7, 3584 CL Utrecht, the Netherlands
| | - Masayasu Taniguchi
- United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi 753-8515, Japan.,Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Mitsuhiro Takagi
- United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi 753-8515, Japan.,Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi 753-8515, Japan
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Bates AJ, Kenyon AG, Laven RA, McDowell JC. Resynchronising returns to service in anoestrous dairy cows in the South Island of New Zealand. N Z Vet J 2016; 64:268-74. [DOI: 10.1080/00480169.2016.1184108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- AJ Bates
- Centre for Dairy Excellence, 20 Wilson Street, Geraldine 7930, New Zealand
| | - AG Kenyon
- North Canterbury Veterinary Clinics, PO Box 58, Culverden 7391, New Zealand
| | - RA Laven
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - JC McDowell
- Vetlife Temuka, 35 King Street, Temuka 7920, New Zealand
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Cuttance EL, Mason WA. Risk factors for and reproductive outcomes of phantom cows on New Zealand dairy farms. N Z Vet J 2015; 63:276-83. [DOI: 10.1080/00480169.2015.1031292] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Adeyinka FD, Laven RA, Lawrence KE, van Den Bosch M, Blankenvoorde G, Parkinson TJ. Association between placentome size, measured using transrectal ultrasonography, and gestational age in cattle. N Z Vet J 2013; 62:51-6. [DOI: 10.1080/00480169.2013.832620] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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Ribeiro E, Lima F, Greco L, Bisinotto R, Monteiro A, Favoreto M, Ayres H, Marsola R, Martinez N, Thatcher W, Santos J. Prevalence of periparturient diseases and effects on fertility of seasonally calving grazing dairy cows supplemented with concentrates. J Dairy Sci 2013; 96:5682-97. [DOI: 10.3168/jds.2012-6335] [Citation(s) in RCA: 189] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 05/14/2013] [Indexed: 11/19/2022]
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Shephard RW. Efficacy of inclusion of equine chorionic gonadotrophin into a treatment protocol for anoestrous dairy cows. N Z Vet J 2013; 61:330-6. [PMID: 23829605 DOI: 10.1080/00480169.2013.809633] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
AIM To compare the performance of intravaginal devices containing 1.0 g (DIB) or 1.38 g (CIDR) progesterone and to determine the efficacy of inclusion of equine chorionic gonadotrophin (eCG) into progesterone-based anoestrous cow treatment protocols for New Zealand dairy cows. METHODS Anoestrous cows (n = 1,906) from 12 herds were randomly assigned to four treatments: 100 μg gonadorelin (GnRH) at Day -10; 500 μg cloprostenol at Day -3; 100 μg GnRH at Day -1 and fixed time artificial insemination (FTAI) on Day 0 (gonadotrophin-prostaglandin-gonadotrophin [GPG] group, n = 475); GPG with CIDR device (1.38 g progesterone) inserted between Day -10 and Day -3 (CIDR group, n = 477); GPG with DIB device (1.0 g progesterone) inserted between Day -10 and Day -3 (DIB group, n = 477); and DIB with 400 IU eCG at Day -3 (DIB + eCG group, n = 477). Conception rates to FTAI and pregnancy at Day 28 were analysed using generalised estimating equations (GEE). Time to conception and time to return to oestrus were analysed using Kaplan-Meier survival analysis and Cox's proportional hazards regression. RESULTS The proportion of cows conceiving to FTAI was 0.34 (95%CI = 0.29-0.37), 0.38 (95%CI = 0.34-0.43), 0.38 (95%CI = 0.33-0.42) and 0.41 (95%CI = 0.37-0.46) for GPG, CIDR, DIB and DIB + eCG groups, respectively. The proportion of cows pregnant by Day 28 was 0.55 (95%CI = 0.51-0.60), 0.57 (95%CI = 0.52-0.61), 0.56 (95%CI = 0.52-0.60) and 0.63 (95%CI = 0.59-0.67) for GPG, CIDR, DIB and DIB + eCG groups, respectively. There was an interaction between treatment and number of days calved (p < 0.05). Cows more than 60 days calved and treated with DIB + eCG had higher FTAI conception and 28-day pregnancy rates than cows treated with GPG (p < 0.001). Median interval to conception did not differ between treatments (p > 0.05). There were no differences between DIB and CIDR groups for any parameter (p > 0.05). The range of the relative risk distribution among herds comparing DIB + eCG to DIB groups was greater than that comparing CIDR to DIB groups for conception to FTAI and pregnancy at Day 28. CONCLUSIONS The inclusion of eCG into progesterone-based anoestrous cow treatment protocols improves conception to FTAI and 28-day pregnancy rates in cows >60 days calved at treatment compared with a GPG protocol. There was no difference in clinical performance between DIB and CIDR devices. CLINICAL RELEVANCE The combination of a low payload (1.0 g) progesterone releasing intravaginal device with eCG treatment at device removal within a GPG treatment is a clinically effective treatment for anoestrous in New Zealand dairy cows.
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Affiliation(s)
- R W Shephard
- a Herd Health Pty. Ltd ., 65 Beet Road, Maffra , VIC , 3860 , Australia
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McDougall S, de Boer M, Compton C, Leblanc SJ. Clinical trial of treatment programs for purulent vaginal discharge in lactating dairy cattle in New Zealand. Theriogenology 2013; 79:1139-45. [PMID: 23499414 DOI: 10.1016/j.theriogenology.2013.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 12/20/2012] [Accepted: 02/06/2013] [Indexed: 11/26/2022]
Abstract
Studies of treatment of postpartum endometritis in dairy cows indicate that prostaglandin (PGF2α) might result in similar outcomes as intrauterine antibiotics, but the effect might depend on the presence of a CL. The objective was to compare reproductive performance in cows with purulent vaginal discharge treated on the basis of having or not having a CL (CL-dependent treatment; CLdep), versus treatment of all affected cows with an intrauterine antibiotic alone. Cows (N = 756) from 36 seasonal calving dairy herds in New Zealand were enrolled on the basis of having a vaginal discharge score (VDS) ≥2 (mucus with flecks of pus or more purulent) after examination with the Metricheck device (Simcro, Hamilton, New Zealand) and ≥14 days after calving. The presence of a CL was assessed by transrectal palpation. Cows were randomly assigned within farm to be treated with an intrauterine antibiotic (0.5 g cephapirin) irrespective of CL status, or treated with PGF2α if a CL was present and cephapirin if a CL was not present (CLdep). The VDS was reassessed 14 days later. Cows were bred using standard practices and pregnancy was tested to define the date of conception. The proportion of cows clinically cured (i.e., with a VDS ≤1 at reexamination) did not differ between treatment groups (0.82 ± 0.03 vs. 0.80 ± 0.03) for the group of cows treated with an intrauterine antibiotic irrespective of CL status and the CLdep groups, respectively (P = 0.66). The proportions of cows submitted for AI by 21 days into the breeding program, pregnant to first breeding, pregnant by 42 days into the breeding program, and at the end of the breeding program, and the interval from the start of the mating program to pregnancy did not differ among treatment groups. Cows that had positive VDS (i.e., >1) at Day 14 after treatment had lower proportions of conception and pregnancy than those with lower (<2) VDS. A treatment protocol in which cows with purulent vaginal discharge with a palpable CL were treated with PGF2α and those without a CL with intrauterine cephapirin resulted in reproductive performance that was not inferior to treating all cows with an intrauterine antibiotic.
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Herlihy M, Crowe M, Berry D, Diskin M, Butler S. Factors associated with fertility outcomes in cows treated with protocols to synchronize estrus and ovulation in seasonal-calving, pasture-based dairy production systems. J Dairy Sci 2013; 96:1485-98. [DOI: 10.3168/jds.2011-5250] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 11/09/2012] [Indexed: 11/19/2022]
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Ribeiro E, Monteiro A, Lima F, Ayres H, Bisinotto R, Favoreto M, Greco L, Marsola R, Thatcher W, Santos J. Effects of presynchronization and length of proestrus on fertility of grazing dairy cows subjected to a 5-day timed artificial insemination protocol. J Dairy Sci 2012; 95:2513-22. [DOI: 10.3168/jds.2011-4921] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Accepted: 12/19/2011] [Indexed: 11/19/2022]
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Ribeiro E, Cerri R, Bisinotto R, Lima F, Silvestre F, Greco L, Thatcher W, Santos J. Reproductive performance of grazing dairy cows following presynchronization and resynchronization protocols. J Dairy Sci 2011; 94:4984-96. [DOI: 10.3168/jds.2011-4225] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 05/18/2011] [Indexed: 11/19/2022]
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