Insemination Interval Research Articles

Success of Artificial Insemination in Rural Area Cows

Biotechnologies of reproduction like artificial insemination were identified as a mean to intensify the local production. Therefore, some factors are still responsible to the failure of their applications in rural area. This survey was conducted from April to June 2023, to evaluate the effects of age, body weight, body condition score (BCS), calving rank, postpartum to artificial insemination interval and feed complementation on the success rate of artificial insemination in females Goudali. Thus, activities took place at two peri-urban livestock farms in the town of Ngaoundéré, in the Adamaoua region of Cameroon where 34 cows were concerned. The selected cows have an average of 8.21±2.41 years old, a body weight of 343±52.28 kg, a body condition score of 3.23±0.55, a calving rank of 2.21±1.22 and a postpartum to insemination interval of 4.39±1.40 months. The induction and synchronization of estrus were carried out based on the PRID-PGF2α-PMSG protocol which allowed to obtain a synchronization rate of 97.06% and the insemination were done 56-57 hours after the previous operation, with an imported semen of Brahman bull. During rectal palpation and early pregnancy diagnosis based on progesterone level measurement, the result shown that, 20 cows out of 33 inseminated were pregnant. The success rate of artificial insemination recorded was 60.6%. Amongst all the studied factors, analysis shown no significant (P> 0.05) effect on the success rate after artificial insemination. Thus, recommendations were made to popularize the use of artificial insemination and early pregnancy diagnosis test as a mean to improve reproductive performances of local farms. However, studies must be done to evaluate the cost of their applications in rural areas.

How does a beef × dairy calving affect the dairy cow's following lactation?

For beef semen usage on dairy cows, much of the research has focused on the performance of the crossbred calves, yet little focus has been given to the subsequent performance of the cow herself. This study aimed to evaluate the performance of dairy cows for milk yield, fertility, and survival traits after giving birth to beef x dairy crossbred calves and compare this with the performance after giving birth to purebred dairy calves. Further, we aimed to study if the effect of a difficult calving was the same regardless of whether the calf was purebred dairy or beef x dairy crossbred. Phenotypic records from 587,288 calving events from 1997 to 2020 were collected from the Swedish milk recording system from cows of the dairy breeds Swedish Red (SR) and Swedish Holstein (SH). The sire beef breeds studied were Aberdeen Angus, Hereford (combined in category LIGHT), Charolais, Limousin, and Simmental (category HEAVY). Sixteen traits were defined and grouped in 3 categories: cumulative and 305-d milk, fat, and protein yield, daily milk yield, and 75-d milk yield as yield traits; calving to first insemination interval, calving to last insemination interval, first to last insemination interval, calving interval, and number of inseminations as fertility traits; and survival to 75 d or to next calving and lactation length as measures of survival. The data were analyzed for all traits for first and second parities separately using mixed linear models, with a focus on the estimates of cow breed by service sire breed combinations. All traits in parity 2 were adjusted for previous 305-d milk yield based on the expectation that low-yielding cows would more likely to be inseminated with beef semen. Overall, milk yield was lower after beef x dairy calvings compared with the purebred dairy calvings. The largest effects were found on cumulative yields and in second parity, with lower effects for yields early in lactation and yields in first parity. The largest decrease was 13-14 kg (0.12 phenotypic SD) for cumulative fat yield when breeding beef breed sires with purebred SR dams. For fertility traits, for most breed combinations, the effects were not large enough to be significant. Conversely, all beef x dairy crossbred combinations showed significantly lower results for survival to the next lactation, and mostly also for lactation length. There was some indication that dairy cows with beef x dairy calvings in parity 2 that were the result of maximum 2 inseminations in parity 1, had lower survival than corresponding calvings resulting from more than 2 inseminations. This could indicate that the former cows were marked for culling already when inseminated. There was generally an unfavorable effect of a difficult calving on all traits, however, there were almost no significant interactions between calving performance and dam by sire breed combination, and these interactions were never significant in first parity.

Genetic improvement of duration of fertility in chickens and its commercial application for extending insemination intervals

The growth rate of chickens has made remarkable progress in recent decades through continuous breeding efforts. However, this advancement has also led to a decline in fertility among commercially bred chickens. Therefore, it is crucial to understand and improve factors that influence fertility to ensure the continued success of the industry. Here, we conduct a 3-generation selection experiment within 2 purebred female lines, with the aim of increasing the duration of fertility (DF). Duration of fertility refers to the length of time hens remain capable of producing fertilized eggs and is a crucial factor that directly impacts chick output. The results showed that significant genetic progress was achieved in embryo survival rates and the fertility duration day during both the peak and late laying periods. Moreover, after 3 generations of selective breeding, the disparities in embryo survival and chick health rates from setting eggs between 8-d and 5-d insemination intervals in the grandparent stock were significantly reduced. The rates decreased from 1.83% and 2.39 to 0.72% and 0.33%, respectively. Surprisingly, the hatching performances of hens with an 8-d interval were comparable to those hens that had not undergone genetic selection for DF and had a 5-d interval. We further discussed the possibility of extending the insemination interval to 8 d in parent stock for commercial practices. The parental populations exhibited remarkable performance in terms of percentages of embryo survival and healthy chicks from the setting eggs, with rates exceeding 94 and 90%, respectively. Thus, it can be inferred that an extended insemination interval is feasible by genetic selection for DF. These findings will provide valuable insights into the efficacy of genetic selection in enhancing DF and its practical application in commercial breeding programs.

Comparative analysis of various methods for estimating expected genetic gain of production and reproduction traits in Murrah buffaloes

The present study was conducted to assess the expected genetic gain for first lactation production and reproduction traits in Murrah buffaloes, in addition to optimization of progenies/sire. Data for period 1971–2020 were used from National Dairy Research Institute. Performance traits considered were 305 days milk yield (305DMY), average daily milk yield (ADMY), peak yield (PY), lactation length (LL), calving to first insemination interval (CFI), days open (DO), and calving interval (CI). Expected ΔG was estimated and compared by three different methods; method I involved heritability and selection differential; method II involved selection intensity, phenotypic standard deviation, and heritability; method III involved estimation of ΔG through four paths of inheritance. Initially, eleven progenies/sire were utilized for assessing expected ΔG by method III, and expected ΔG was found as 34.33, 0.12, 0.12 kg, 2.63, 1.51, 2.74, and 2.80 days/year for 305DMY, ADMY, PY, LL, CFI, DO, and CI, respectively. Additionally, there was a significant increase in expected ΔG on increasing progenies/sire from 6 to 11 while subsequent increase upto 16 had little effect on expected ΔG. These findings will be helpful in formulating breeding strategies worldwide in small buffalo herds to obtain sustainable ΔG in production and reproduction traits.

Efekt koncentrace beta-hydroxybutyrátu v krvi na reprodukci, produkci a zdraví krav v prvních týdnech po otelení

The constant monitoring of dairy cow metabolism is extremely important, especially in the period immediately after calving, when the animals face the consequences of negative energy balance. The concentration of beta-hydroxybutyrate is one of the reliable indicators of metabolic status. The aim of this work was to evaluate the effect of beta-hydroxybutyrate concentration in the blood on selected parameters of production, reproduction, and health of Holstein dairy cows. The limit for subclinical ketosis was set to >1.2 mmol/L of beta-hydroxybutyrate in blood. Furthermore, the effects of lactation number, season, and year of assessment were added to the model equation. The results showed that high beta-hydroxybutyrate concentration in blood is associated with poor reproduction parameters (worse insemination interval and service period) and lower milk production. However, the results were ambiguous in relation to the somatic cell count and the occurrence of selected diseases (mastitis and ovarian cysts). Moreover, the effect of seasonality on the evaluated parameters was also confirmed (P<0.05), while assessed years were similar in most parameters. It can be concluded that the assessment of beta-hydroxybutyrate concentration as an indicator of potential ketosis is important and can be a suitable parameter for routine monitoring as it influences milk production, reproduction, and cow's health.

Hormone use for reproductive diseases and heat induction in relation to herd-level reproductive performance in Dutch dairy farms

This ecological study aimed to associate hormone use for reproductive diseases and heat induction with reproductive performance at herd level. Hormone use, herd characteristics, and test-day recording data were obtained from 754 representative Dutch dairy farms belonging to five large veterinary practices from 2017 to 2019 (1679 observations in total). Hormone use was classified into prostaglandin, gonadotropin-releasing hormone (GnRH), and progesterone, and was expressed at herd level as the annual number of hormone doses per 100 adult dairy cows. Hormone use was categorized into four levels (no usage, low, medium, and high use), following the 33rd and 66th percentiles of herds that applied them. Three herd-level reproductive performance indicators (calving interval, calving-to-1st insemination interval, number of inseminations per cow) were analyzed using multivariable General Estimating Equations models. The median annual total hormone use was 36.1 (mean=43.1; min=0.0; max=248.2) doses per 100 adult dairy cows in all herds while the median was 39.2 (mean=46.8; min=0.4; max=248.2) doses per 100 adult dairy cows among the user-herds. The median annual group-specific hormone use was 21.3 (mean=26.1; min 0.0; max=180.0), 11.0 (mean=15.3; min=0.0; max=127.0) and 0.0 (mean=1.8; min=0.0; max=40.3) doses per 100 adult dairy cows for prostaglandin, GnRH, and progesterone, respectively. The final statistical models identified that herds with a high hormone use had a calving interval and a calving-to-1st insemination interval that was 9.3 ± 2.6 and 16.4 ± 2.1 days shorter than that of non-user herds (424.0 ± 2.7 and 114.0 ± 2.1 days), respectively. Furthermore, high-user herds needed on average 0.3 ± 0.04 inseminations more to get their cows pregnant compared to non-user herds (1.83 ± 0.04 no. of inseminations per cow). Medium-user herds had a 6.5 ± 2.6 days shorter calving interval and a 12.0 ± 2.1 days shorter calving-to-1st insemination interval with 0.2 ± 0.04 additional inseminations per cow compared to non-user herds. Low-user herds had a 6.2 ± 2.7 days shorter calving interval and a 7.9 ± 2.2 days shorter calving-to-1st insemination interval compared to non-user herds. The model produced the same trend for prostaglandin and GnRH use, with the higher use being associated with a shorter calving interval, a shorter calving-to-1st insemination interval, and a higher insemination per cow number. For progesterone use the opposite effect was observed. In conclusion, using a large representative herd-level dataset, hormone use was associated with a better reproductive performance in terms of calving interval and calving-to-1st insemination interval but gave extra average number of inseminations per cow. It should be monitored how reproduction performance changes when striving for a more prudent hormone use.

Evaluation of relative economic value of performance traits in Sahiwal cattle

Estimation of economic values is essential to decide the monetary importance of traits to be incorporated in breeding programs. The present study was conducted to estimate the relative economic value of first lactation traits, viz. 305-day milk yield (305DMY), average daily milk yield (ADMY), calving to first insemination interval (CFI), days open (DO), pregnancy rate (PR) and longevity (LNG) in Sahiwal cattle. Data spanning over duration of 29 years pertaining to production, reproduction and longevity of Sahiwal cattle kept at ICAR-NDRI herd were utilized. Averages of first lactation traits, viz. 305DMY, ADMY, CFI, DO, PR and LNG were obtained as 1822.59 kg, 6.62 kg/day, 85.56 days, 150.48 days, 38.00% and 2711.95 days, respectively with lactation length of 303.02 days in Sahiwal cattle. Expenses involved for different groups of animals for five years (2012-2016) were considered for appraising relative economic values of above-mentioned performance traits. Major expenses considered were per day cost of feeding, treatment, labour and artificial insemination for each animal. Cost of production of one kg milk was calculated as ` 23.68 which was the economic value of 305DMY and ADMY. The per unit expenses for traits CFI, DO, PR and LNG were ` 156.79, 156.79, 86.65, and 141.21, respectively in Sahiwal cattle. Relative economic values were estimated as 1, 1, -6.62, -6.62, 3.66 and 5.96 for 305DMY, ADMY, CFI, DO, PR and LNG, respectively. Relative economic values estimated in the present study will be helpful for constructing selection indices for genetic progress of Sahiwal cattle.

Effect of calving to timed artificial insemination interval on fertility of beef cows.

The objectives of this study were to determine the effect of calving to timed artificial insemination (C-TAI) interval on fertility of Bos taurus and Bos indicus cows and to determine the best C-TAI interval to include postpartum cows in TAI programs in each genotype (B. taurus and B. indicus). In experiment 1, a retrospective study was performed, with data from 2,709 TAI in Bos taurus and Bos indicus cows with different C-TAI intervals. There was a positive linear effect of C-TAI interval on the pregnancy probability (p < .0001). However, there was no effect or interaction with the genotype. When C-TAI intervals were grouped in classes, pregnancy rate differed in groups (p < .05). Receiver operating characteristic (ROC) analysis was performed, and it was observed that 52 days would be the better C-TAI interval to maximize fertility in beef cows. According to the previous result, we further stratified into two C-TAI interval groups (≤ 52 days or > 52 days). Cows with C-TAI longer than 52 days (C-TAI > 52) had greater pregnancy rate (56%) than cows with short C-TAI (46%; p < .01). In experiment 2, 18 postpartum beef cows were subjected to TAI protocol at different C-TAI intervals (n=6 cows per group): 40, 60 or 80 days postpartum. Cows with 60 days of C-TAI had a greater preovulatory follicle diameter than cows with 80 days postpartum (p < .05). The C-TAI interval did not affect (p > .05) the ovulation rate nor the proportion of endometrial polymorphonuclear leucocytes. We conclude that C-TAI interval affects pregnancy rate in both Bos taurus and Bos indicus. We recommend a C-TAI interval longer than 52 days to increase fertility of beef cows included in TAI programs.

Factors affecting calving to conception interval (days open) in dairy cows located at Dessie and Kombolcha towns, Ethiopia.

This study was aimed at determining the median days of calving to conception interval (days open) and identifying the major risk factors determining the days open in dairy cows. Both retrospective and longitudinal studies were conducted on dairy cows located in the Dessie and Kombolcha towns of South Wollo Zone, northeast Ethiopia from August 2019 to August 2020. The Kaplan-Meier model of survival analysis was used to determine the median days open and compare the survival distribution of each level of explanatory variables likely to influence the days open of dairy cows. Accordingly, the overall conception rate of dairy cows was 44.7%. The median days open in the study was 154 days. There is a 16% probability of surviving (i.e, the probability that the conception event has not yet occurred) at the end of 210 days postpartum period. The Cox proportional hazard model was used to quantify the effect of each of the explanatory variables on the days open in the first 210 days postpartum. Factors that had a significant effect (p<0.05) on the calving to conception interval were the season of insemination, breeding system, calving to insemination interval, and herd milk yield level. However, the peripartum, postpartum disorders, and the town of the farm are not significant (p>0.05). Accordingly, cows inseminated in the autumn season (HR = 4.45), cows less than or equal to 85 days calving to insemination interval (HR = 2.41), artificially inseminated cows (HR = 1.45), and high herd milk yield cow had a higher probability of becoming pregnant. In conclusion, the management practices and breeding decisions seem to be important determinants to improve the conception rate or decrease the days open in dairy cows.

Genomic Estimated Breeding Value of Milk Performance and Fertility Traits in the Russian Black-and-White Cattle Population.

A breakthrough in cattle breeding was achieved with the incorporation of animal genomic data into breeding programs. The introduction of genomic selection has a major impact on traditional genetic assessment systems and animal genetic improvement programs. Since 2010, genomic selection has been officially introduced in the evaluation of the breeding and genetic potential of cattle in Europe, the U.S., Canada, and many other developed countries. The purpose of this study is to develop a system for a genomic evaluation of the breeding value of the domestic livestock of Black-and-White and Russian Holstein cattle based on 3 milk performance traits: daily milk yield (kg), daily milk fat (%), and daily milk protein content (%) and 6 fertility traits: age at first calving (AFC), calving interval (CI), calving to first insemination interval (CFI), interval between first and last insemination (IFL), days open (DO), and number of services (NS). We built a unified database of breeding animals from 523 breeding farms in the Russian Federation. The database included pedigree information on 2,551,529 cows and 69,131 bulls of the Russian Holstein and Black-and-White cattle breeds, as well as information on the milk performance of 1,597,426 cows with 4,771,366 completed lactations. The date of birth of the animals included in the database was between 1975 and 2017. Genotyping was performed in 672 animals using a BovineSNP50 v3 DNA Analysis BeadChip microarray (Illumina, USA). The genomic estimated breeding value (GEBV) was evaluated only for 644 animals (427 bulls and 217 cows) using the single-step genomic best linear unbiased prediction – animal model (ssGBLUP-AM). The mean genetic potential was +0.88 and +1.03 kg for the daily milk yield, -0.002% for the milk fat content, and –0.003 and 0.001% for the milk protein content in the cows and bulls, respectively. There was negative genetic progress in the fertility traits in the studied population between 1975 and 2017. The reliability of the estimated breeding value (EBV) for genotyped bulls ranged from 89 to 93% for the milk performance traits and 85 to 90% for the fertility traits, whereas the reliability of the genomic estimated breeding value (GEBV) varied 54 to 64% for the milk traits and 23 to 60% for the fertility traits. This result shows that it is possible to use the genomic estimated breeding value with rather high reliability to evaluate the domestic livestock of Russian Holstein and Black-and-White cattle breeds for fertility and milk performance traits. This system of genomic evaluation may help bring domestic breeding in line with modern competitive practices and estimate the breeding value of cattle at birth based on information on the animal’s genome.

Appraisal and simulation of expected genetic gain for production and reproduction traits in Sahiwal cattle

The present study was undertaken with an objective to assess the expected genetic gain for production and reproduction traits, viz. 305-day milk yield (305DMY), average daily milk yield (ADMY), and calving to first insemination interval (CFI) in Sahiwal cattle. Data spread over a period of 29 years pertaining to production and reproduction traits of Sahiwal cattle maintained at an organized herd of ICAR-National Dairy Research Institute, Karnal, were utilized. Expected genetic gain per generation was assessed based on first and pooled 6 lactation records using 2 different methods, i.e. method I (ΔG = h2S) and II (ΔG = iσph2). Method II, which considered selection intensity and phenotypic standard deviation of the traits led to better estimation in Sahiwal cattle. Further, different parameters involved in methods I and II were simulated to evaluate the expected genetic gain in first lactation traits, viz. 305DMY, ADMY, and CFI. In method I, generation interval was decreased as well as increased for estimating expected genetic gain. Using method I, expected genetic gain increased by about 33, 33, and 43% for 305DMY, ADMY, and CFI with the reduction of generation interval (GI) from 5.31 to 4 years, whereas the expected genetic gain decreased by about 11, 17 and 14% for the above-mentioned traits, respectively, with the increase of GI from 5.31 to 6 years. In method II, with the increase of selection intensity and reduction of GI, a significant increase in ΔG/year for 305DMY, ADMY, and CFI was observed. Present study indicated that generation interval and proportion of Sahiwal animals selected should be less than 5 years and 75%, respectively, for achieving more than 50% expected ΔG/year for 305DMY, ADMY, and CFI in an organized herd.

Development of sustainable performance index based on production, reproduction, health and longevity for genetic improvement of Sahiwal cattle.

An attempt was made for the first time in India to develop the performance indices for quantifying the relative emphasis to be given to production, reproduction, health and longevity traits for selection and genetic improvement of Sahiwal cattle in a sustainable manner. The study was conducted using information related to various production, reproduction, health and longevity traits spread over a period of 29years in Sahiwal cattle. Using income and expenditure method, the relative economic values for 305days milk yield (305DMY), average daily milk yield (ADMY), calving to first insemination interval (CFI), days open (DO) and longevity (LNG) were estimated as 1, 1, -6.62, -6.62 and 5.96 in Sahiwal cattle. A total of three performance indices were constructed using three-trait combination, that is production, reproduction and longevity before and after excluding the days suffered by the animals. Correlation between the aggregate genotype and index (RIH ) was computed to determine the accuracy of each performance index, and based on highest RIH value, best performance index was identified for selection of Sahiwal cattle. Developed indices were further assessed for robustness by increasing the relative economic values of the traits by 25% and 50%. The performance index (305DMY, DO and LNG) was found to be the best index before as well as after excluding days suffered by the animals, but in later case emphasis to be given to different traits was found to be more balanced. The best index indicated that about 47, 42 and 11% relative emphasis to be assigned to 305days milk yield, days open and longevity for selection of Sahiwal animals for sustainable genetic improvement.

Lactation wise performance of Sahiwal cattle at an organized herd of northern India

Performances of different production, reproduction traits and longevity up to sixth parity in Sahiwal cattle maintained at ICAR-National Dairy Research Institute over a period of 29 years (1988–2016) were assessed. Parity wise means along with standard errors of different traits were estimated up to sixth parity in Sahiwal cattle using Descriptive Statistics in SPSS software. 305 days milk yield, total milk yield, lactation length, wet average, peak yield, days to attain peak yield and dry period varied from 1,822.59 to 2,166.36 kg, 1,822.59 to 2259.86 kg, 268.95 to 303.02 days, 6.62 to 7.93 kg/day, 10.64 to 14.09 kg, 38.67 to 51.68 days and 118.11 to 142.05 days, respectively in different parities up to sixth parity in Sahiwal cattle. Average age at first service was 26.46 months in Sahiwal cattle. Age at calving, number of services per conception, conception rate, gestation period, calving to first insemination interval, service period, calving interval and pregnancy rate ranged from 37.70 to 105.59 months (1,131–3,168 days), 1.84–2.02, 66.19–70.07%, 286.76–287.97 days, 72.65–87.61 days,113.48–150.48 days, 401.47– 443.47 days and 38–44%, respectively in different parities. The average longevity ranged from 7.43 to 11.35 years (2,711.95–4,142.75 days) in Sahiwal cattle up to sixth parity. In the present study, milk yield increased up to third parity and declined in further parities. Highest test day milk yield was recorded in second test day in each lactation up to sixth parity while lowest was observed in last test day.

Unraveling the actual background of second litter syndrome in pigs: based on Large White data

Second litter syndrome (SLS) in sows is when fertility performance is lower in the second parity than in the first parity. The causes of SLS have been associated with lactation weight loss, premature first insemination, short lactation length, short weaning to insemination interval, season, and farm of farrowing. There is little known about the genetic background of SLS or if it is a real biological problem or just a statistical issue. Thus, we aimed to evaluate risk factors, investigate genetic background of SLS, and estimate the probability of SLS existing due to the statistical properties of the trait. The records of 246 799 litters (total number born, TNB) from 46 218 Large White sows were used. A total of 15 398 sows had SLS. Two traits were defined: first a binominal trait if a sow had SLS or not (biSLS) and second a continuous trait (Range) created by subtracting the total number of piglets born in the first parity (TNB1) from the piglets born in the second parity (TNB2). Lactation length, farm, and season of the farrowing had significant effects on SLS traits when tested as fixed effects in the genetic model. These effects are farm management-related factors. The age at first insemination and weaning to insemination interval were significant only for other reproduction traits (e.g., TNB1, TNB2, litter weight in parity 1 and 2). The heritability of biSLS was 0.05 (on observed scale), whereas heritability of Range was 0.03. To verify the existence of SLS data with records of 50 000 sows and 9 parities was simulated. The simulations showed that the average expected frequency of SLS across all the parities was 0.49 (±0.05) while the observed frequency in the actual data was 0.46 (±0.04). We compared this to SLS frequencies in 67 farms and only 2 farms had more piglets born in the first parity compared to the second. Therefore, on the individual sow level SLS is likely due to statistical properties of the trait, whereas on the farm level SLS is likely due to farm management. Thus, SLS should not be considered an abnormality nor a syndrome if on average the herd litter size in parity 2 is larger than in parity 1.

Effects of semen dosage, oviductal sperm storage and insemination interval on egg fertility, embryo mortality and hatchability in Nera Black breeder chickens

The biological basis of sustaining fertility in poultry is their ability to store sperm cells in the sperm storage tubules (SST) located in the uterovaginal junction. However, artificial insemination in poultry industry is haphazardly administered in Nigeria without regulation on semen dose and frequency of insemination for optimum fertility. The objective of this study was to establish a semen dosage and insemination interval for maximum fertility and embryonic survival in Nera black layer breeder chickens. A total of 80 breeder hens (52 weeks) were allotted to five (5) treatments with four (4) replicate per treatment. Semen was pooled from 10 matured breeder cocks and inseminated to four groups of hens at varied semen dose of 0.02mL (T1), 0.04mL (T2), 0.06mL (T3) and 0.08mL (T4) of undiluted semen while hens in T5 were mated naturally, both for two consecutive days. 0.02, 0.04, 0.06 and 0.08mL of pooled semen contained 20.43×10 , 40.87×106 , 61.30×106 and 81.74×106 motile spermatozoa. Eggs were collected, stored and artificially incubated weekly for 4 weeks. Fertility, embryo mortality and hatchability parameters were determined. Another 78 breeder hens were allocated into 4 treatments of 5 replicates per treatment with unequal number of hens and were inseminated with 0.02mL of raw semen containing 20.43 × 106 motile sperm cells at 3, 6, 9 and 12 days intervals. Fertility, hatchability and embryo mortality were determined. Data were analysed using descriptive statistics and ANOVA at &amp;0.05 Hatch of fertile eggs in T5 at week 2 (65.36±13.28) was significantly higher (p&lt;0.05) . than T1 (33.83±12.65), T2 (13.25±6.88), T3 (39.17±14.17) and T4 (28.21±11.37). At weeks 1 and 2, there was no significant different across the treatments. Fertility at 4 weeks in T1 (11.53±6.66) was significantly (p&lt;0.05) different from treatments T2 (0.00±0.00), T3 (0.00±0.00), T4 (1.66±1.66) and T5 (0.00±0.00). Total and early embryo mortality in week 3 was significantly higher (p&lt;0.05) in T1 (100.00±0.00, 95.00±5.00) than in treatments T2 (43.75±0.00, 43.75±25.77), T3 (66.67±23.57, 66.67±23.57), T4 (95.00±5.00, 85.00±15.00) and T5 (37.50±23.94, 22.92±15.73). Fertility was significantly (p&lt;0.05) higher in 3 days insemination interval (52.65±7.25) compared with 6 days (39.87±4.70), 9 days (22.98±5.71) and 12 days (36.14±6.89). At weeks 1 and 3, the hatch of fertile eggs across the treatments was not significantly (p&gt;0.05) different from one another. This study suggests that 6 inseminating semen dose of 0.02mL containing approximately 20.43×10 motile sperm cells in Nera black layer breeder chickens will give a maximum fertile period of 5 days, while insemination interval of 3 days using 0.02mLof semen gave highest fertility level.

Genetic and genomic analysis of long insemination interval in Israeli dairy cattle as an indicator of early abortions

One of the causes of observed low fertility is embryo loss after fertilization. Previous findings suggested that more than half of fertilizations result in embryo loss before pregnancy is detected. We proposed reinsemination between 49 and 100 d after the first insemination as an indicator trait for early abortion (EA) in dairy cattle based on the mean estrus interval of 21 d. This trait was compared with conception rate from first insemination and conception status, computed as the inverse of the number of inseminations to conception. Animal model variance components were estimated by REML, including parents and grandparents of cows with records. First-parity heritability for first insemination conception rate was 3%. In the multitrait analysis of parities 1 to 3 for putative EA, heritabilities ranged from 8.9% for first parity to 10.4% for second parity. All genetic correlations were >0.9, whereas all environmental correlations were <0.12. The variance component for the service sire effect for putative EA rate was less than half the variance component for conception rate. Thus, genetic control of the 2 traits is clearly different, and analysis of EA rate by a single-trait animal model is justified. Genetic evaluation for putative EA was computed using this model, including all first- through third-parity cows with freshening dates from January 1, 1985, through December 31, 2016, that either became pregnant on first insemination or were reinseminated between 49 and 100 d after the first insemination. All known parents and grandparents of cows with records were included in the analysis. The regression of the breeding value for non-abortion rate on the cows' birth year was 0.083%/yr. The genetic correlation between first-parity EA and conception status was 0.995. The genetic correlations between first-parity EA and milk, fat, and protein production were all negative, whereas the genetic correlation between EA and herd life was 0.33. Inclusion of putative EA in the selection index instead of conception status resulted in 10 to 20% greater genetic gain for both fertility traits. In a genome-wide association study based on 1,200 dairy bulls with reliabilities >50% for abortion rate genotyped for 41,000 markers, 6 markers were found with nominal probabilities of <10-12 to reject the null hypothesis of no effect on EA rate. The markers with the lowest probabilities for EA rate were also included among the markers with the lowest probabilities for female fertility, but not vice versa. The marker explaining the most variance for abortion rate is located within the ABCA9 gene, which is found within an ATP-binding cassette (ABC) genes cluster. The ABC family is the major class of primary active transporters in the placenta.

Assessment of relation among production and reproduction traits in Sahiwal cattle at an organized herd of northern India

ABSTRACT The present study was conducted to assess the relation between different production and reproduction traits in Sahiwal cattle. Data up to sixth parity related to different production and reproduction traits of Sahiwal cattle maintained at an organized herd of ICAR-National Dairy Research Institute, Karnal spread over a span of 29 years (1988–2016) were utilized. Various production and reproduction traits considered were 305-day milk yield (305DMY), total milk yield (TMY), lactation length (LL), dry period (DP), age at calving (AAC), calving to first insemination interval (CFI), days open/service period (DO), calving interval (CI) and pregnancy rate (PR) up to sixth parity. Genetic and phenotypic correlations between different production and reproduction traits were estimated in addition to analysis of graphs between these traits up to sixth parity in Sahiwal cattle. The genetic correlations of 305DMY, TMY and LL with DO and CI were positive. Likewise, the phenotypic correlations of 305DMY, TMY and LL with CFI, DO and CI were significantly positive suggesting that cows with high milk yield have longer calving to first insemination interval, days open and calving interval. These findings confirm antagonistic relation between production and reproduction traits. Therefore, reproduction traits should also be taken into consideration along with production traits for genetic evaluation, selection of superior germplasm as well as for formulating suitable breeding programs for sustainable genetic improvement of Sahiwal cattle. Abbreviations: AAC, age at calving; CFI, calving to first insemination interval; CI, calving interval; 305DMY, 305-day milk yield; DP, dry period; DO, days open; LL, lactation length; TMY, total milk yield; PR, pregnancy rate

Relative effect of milk constituents on fertility performance of milk-recorded, spring-calving dairy cows in Ireland

Several studies have reported associations between milk composition data and fertility performance. However, no work to date has estimated the effect of milk constituents on fertility performance in cows with low milk constituent concentrations. The objective of this study was to assess the association between milk constituents, animal characteristics, and time from mating start date (MSD) to conception using survival analysis. Furthermore, we aimed to investigate the relative effect of each variable by predicting median times to conception for animals with different combinations of characteristics and milk compositions. The final data set consisted of 87,227 cow lactation records from 64,519 cows in 2,049 herds with calving dates from 2010 to 2013. Milk recording data from each lactation were used, including test day recordings at 0 to 30, 31 to 60, and 61 to 90 d in milk (DIM). The analysis was limited to spring-calving cows (i.e., animals calving from January to May inclusive). Mating start date was determined for each unique herd in each year. A cow-specific MSD (MSDcow) was defined taking into consideration the MSD for each herd and the calving date and a minimum calving to insemination interval of each herd year. The conception date for each cow was estimated using the subsequent calving date. Cows with no subsequent calving date were assumed not to have conceived. Time from MSDcow to approximate conception date was analyzed using survival analysis. Cox proportional hazard models were constructed for each of the 3 recording windows: 0 to 30, 31 to 60, and 61 to 90 DIM. A fourth model was used to assess the dynamics of milk composition over the 3 windows. To investigate the effect of these variables, model outputs were used to create parametric accelerated failure time models to predict median survival times for animals at the 10th and 90th percentiles of the variable of interest but otherwise identical across the rest of the variables. Results demonstrated that fertility breeding subindex had the largest effect on time from MSDcow to conception, with an additional 62 d open for those in the 10th percentile versus those in the 90th percentile. Of the milk constituents, milk lactose concentration had the greatest effect on MSD to conception, particularly when measured from 0 to 30 DIM. An additional 10 d open resulted from comparing those in the 10th and 90th percentiles. Milk protein concentration, although statistically significant, had a lower effect on fertility outcome when comparing cows in the 10th and 90th percentiles for this exposure variable. The greatest effect was found in the 61 to 90 DIM recording window, where cows in the 10th percentile had an additional 9 d open at the subsequent breeding season compared with those in the 90th percentile. Overall, our study shows that although the associations between milk constituents and fertility are statistically significant, their overall influence in determining MSD to conception in this study population is relatively modest, particularly compared with fertility breeding subindex, when comparing cows at the 10th and 90th percentiles. Of the milk constituents measured, milk lactose concentration measured at 0 to 30 DIM had the greatest effect in determining fertility outcome when comparing cows at the 10th and 90th percentiles. The predictive value of early-lactation test day milk composition data on hazard of pregnancy during the following breeding period, within a spring-calving context, appears to be relatively modest at the individual-cow level. Further work is required to test the usefulness of these associations at the herd level.

The Effects of Sperm Number and Insemination Interval on the Fertility and Hatchability of Sentul Hens

Sexually mature Indonesian native hens (Sentul hens) were housed singly in laying cages and artificially inseminated with combination of three different levels of diluted pooled semen (50 million sperm/0.05 ml; 100 million sperm/0.1 ml; and 150 million sperm/0.15 ml) and at either of three different intervals (every 3, 6 and 9 days). The results show that the sperm number and Insemination intervals had no significant interaction (P>0.05) on % fertility and hatchability. The best fertility around 90 %; P<0.05 was obtained by inseminating interval 6 days with sperm number 100 million/0.1 ml of diluted semen.

Changes in climate conditions and their effects on production and reproduction of medium yielding cows in temperate continental climate

The increased air temperature combined with the reduction of rainfall during hot season impairs the capacity of cows to maintain the optimal body temperature. This study tested the hypothesis that climate changes affect the medium yielding cows in temperate continental climate. The productive-reproductive parameters of 8607 milking cows from a dairy farm in North-eastern Romania were examined and correlated with changes in ambient temperatures and rainfall between the years of 1983 and 2010. We observed that the number of artificial inseminations served to cows showed a decreasing trend. The reduction in this parameter was significantly influenced by the increase in the average and maximum temperatures during hot season associated with the reduction in rainfall, as shown by regression analysis. Other studied parameters such as milk production, calving to conception interval, calving to first artificial insemination interval and conception rates at first, second and more than two services were not related to the changes in average annual temperatures, annual temperatures amplitude and annual precipitation quantities. This study suggests that, although present, the effects of climate changes on some productive-reproductive parameters of medium yielding cows in geographic areas with temperate continental climate are not as dramatic as described in other studies.