Genetic Parameters for Productive Longevity in Limousine Breed

Prediction of Longevity Breeding Values for US Holstein Sires Using Survival Analysis Methodology

Comparison of piecewise Weibull baseline survival models for estimation of true and functional longevity in Brown cattle raised in small herds

Recently, in the breeding and commodity farms of our country can be observed a rapid decrease in the duration of productive use dairy cattle. A considerable amount of scientific researches are conducted on the effects of hereditary and environmental factors on productive indicators longevity, researches are done on various ways to increase durability productive use of dairy cattle. In this aspect, reproductive ability of cows is important, which must be taken into account while individual estimation for the next selection of the most valuable animals that combine high milk productivity with high fertility. Therefore, the goal of our research was to study the productive longevity of dairy cows depending on the duration of their first service period and find the optimal duration of this indicator for a particular breed. The research was carried out on cows of Holstein, Ukrainian Black-and-White and Red-and-White breeds. Retrospective analysis of duration and the effectiveness of life-time use of cows was carried out according to the method Yu P. Polupan (2010). It was found that average duration of the first service-period of cows was 167.7 days on the studied Holstein populations, 180.3 – on the Ukrainian Black-and-White and Ukrainian Red-and-White – 142.1 days. The longest duration of life, productive use, lactations and the highest milk yields had cows with the duration of the first service period of 121–150 days among the Holstein breed, 151–180 – Ukrainian Black-and-White and 91–120 days and Ukrainian Red-and-White. The worst, by the indicators of productive longevity, were individuals with 60 days and no more of the first service period. Correlation analysis showed the different level of the connection between the duration of the service period animals and indicators of their lifelong use, which in most cases had a reverse nature. This kind of connection indicates that with the extension of the duration of service period of cows, the duration of their productive use and lifetime productivity decreases. In Holstein breed animals, the correlation coefficients between the above named indicators ranged from -0.462 to 0.370, Ukrainian Black-and-White – from -0.113 to 0.144 and Ukrainian Red-and-White – from 0.279 to 0.149. Strength of influence of the duration of the first service-period on life duration, productive use and lactation of cows, depending on the breed, was 12.5–36.5%, for lifetime productivity – 9.7–34.6 and on the one day of life, productive use and lactation – 11.3–35.9%.

Impact of conformation traits on functional longevity of Holstein cattle of Iran assessed by a Weibull proportional hazards model

Study on functional longevity of Tunisian Holstein dairy cattle using a Weibull proportional hazard model

The article presents the results of a study of the influence of the age of the 1st insemination of holstinized heifers on the milk productivity and productive longevity of cows. In general, over the past 13 years, a pronounced tendency has been observed in the studied herd to reduce the age of the 1st insemination by 3.5 months. Studies showed that the average age of abandonment of animals is positively associated with the age of the 1st insemination, i.e. the higher the average age of the 1st insemination of heifers, the higher the average age of abandonment (IOS) of cows, i.e. higher productive longevity of animals. Live weight and average daily growth of heifers inseminated at the age of 12 months. were noticeably higher than others. Analysis of the milk productivity of first-calf cows showed that among animals of all groups, in general, animals inseminated in 14 and 15 months turned out to be somewhat more productive. Studies have established that there is a negative relationship between the age of the 1st insemination and the age of manifestation of maximum milk yield of cows: the earlier the heifer is inseminated, the later it shows maximum productivity. At the optimal age of the 1st insemination, a cow can lactate in a herd of at least 3 lactation. Reducing the age of the 1st insemination leads to a reduction in productive longevity. In order to increase productive longevity in the conditions of this farm, it is not recommended to inseminate heifers earlier than 14 months.

Increasing the productive longevity of cows with high reproductive ability is an urgent task in dairy cattle breeding both in Russia and foreign countries. Research was conducted in Krasnoyarsk region. The object was retired cows (n = 484). The blood groups of cows, indicators of productive longevity, and reproductive ability of cows were studied. The number of antigen carriers and non-carriers (frequency 30.0% and more) was analyzed. Out of 21 antigens with a frequency of more than 30.0%, the most frequently encountered antigens were E (80.6%), H` (77.5%), L (58.5%), W (57.6 %), A2 (57.0%), Z (54.1%), C (52.5%) and X2 (50.4%). The cows carrying O1 antigen had the highest productive longevity, – the difference from the cows not carrying this antigen by the retirement and lactation age was 0.8 years (p <0.001), and the period of economic use was 9.5 months (p <0.001), life-long milk yield was 3852 kg (p <0.001). Cows carrying antigens G3, O1, and L` had the best reproductive ability. In carriers of antigens O1, G3, and E`3, the service period was lower by 22.9; 20.3 and 18.9 days (p <0.05), and the fertility index was higher by 1.8; 1.6 and 1.7 units (p <0.05). In cows carrying L` antigen, the service period was shorter by 16.9 days (p <0.05).

Currently, marker genes are often used in dairy cattle breeding. Scientists are studying the relationship of gene polymorphism with such economically useful traits as milk productivity, productive longevity, growth, development, etc. The short period of the economic use of cows and the late intake of live weight necessary for insemination cause economic losses to agricultural organizations. The goal of the research was to study the relationship of the polymorphism of the somatotropin gene with live weight during the first insemination and productive longevity of cows. The study was conducted in the Sverdlovsk region on cattle of Holstein Black-Motley breed in 2018–2019. Two samples were formed: heifers and retired cows genotyped by the somatotropin gene. In animals, LV-somatotropin gene polymorphism was determined. The determination of polymorphism included the following steps: DNA isolation, polymerase chain reaction (PCR), restriction enzyme production, restriction products run on an agarose gel, visualization using a transilluminator. The research results were processed using IBM SPSS Statistics 23 software,and the reliability criterion was analyzed. LV-polymorphism is represented by three genotypes: LL,LV and VV. The authors studied the frequency of genotypes in the population of holsteinized cattle. It was revealed that the LL genotype is widely represented in the population – 77.2%, animals with the LV genotype are found more rarely – 22.2%. The VV genotype is extremely rare in the population – 0.6%. It was also revealed that the L allele is a common population allele – 88.3%. In the course of studying the relationship of LV polymorphism with live weight during the first insemination, it was found that animals with the LL genotype grow faster and reach the live weight necessary for fruitful insemination earlier. At the same age, heifers with the LV genotype had a mass of 400 kg, with those with the LL genotype – 9 kg more at p ≤ 0.01. When studying the effect of somatotropin gene genotypes on productive longevity, it was found that cows with the LV genotype have a longer economic use. The difference with peers with the LL genotype was 0.5 lactations at p ≤ 0.05. As a result of the studies, it can be concluded that the LL and LV genotypes are the desired option for the holsteinized cattle population. The LL genotype is associated with growth and development, and LV – with productive longevity.

The Weibull proportional hazards model was used to identify the nongenetic effects that affect length of productive life (LPL) of the Italian Mediterranean buffalo. Data were provided by the Italian National Association of Buffalo Breeders and included records of reproductive, productive, and linear type traits from 59,943 buffalo with first calving from 2002 to 2019. Data were divided into 4 geographical regions to determine whether the relationship between the investigated effects and LPL varied by region. Length of productive life was defined as the number of days from the first calving to culling for those buffaloes that were culled (uncensored) or to the date of the last test-day for those that are still alive (censored). The Weibull model included time-dependent effects of herd-year-season of calving, parity and stage of lactation, production as within-herd deviations, as well as time-independent effects of age at first calving, year of birth, type of reproduction (natural mating vs. AI), classifier, and ten linear type traits. The average duration of productive life was 1,604 days. Both year of birth and production level had a significant effect on culling risk. Moreover, culling risk decreased linearly across parities. The reference point for age at first calving relative to other classes was set at 35 months. A significant relationship between linear type traits and relative culling risk was also observed, being highest for buffaloes with the lowest linear scores. The results show that the Weibull model provides consistent and robust risk estimates. Therefore, this model would be recommended for future implementation of the first genetic evaluation of LPL in the Italian Mediterranean buffalo.

In this paper, we present a Bayesian analysis for the Weibull proportional hazard (PH) model used in step-stress accelerated life testings. The key mathematical and graphical difference between the Weibull cumulative exposure (CE) model and the PH model is illustrated. Compared with the CE model, the PH model provides more flexibility in fitting step-stress testing data and has the attractive mathematical properties of being desirable in the Bayesian framework. A Markov chain Monte Carlo algorithm with adaptive rejection sampling technique is used for posterior inference. We demonstrate the performance of this method on both simulated and real datasets.

Analysis of the Relationship Between Type Traits and Functional Survival in US Holstein Cattle Using a Weibull Proportional Hazards Model

The foundation stock of dairy cattle in the country is represented by animals of the Holstein breed, the most abundantly dairy in the world. The breeding of Holstein cattle is carried out along the lines and it is interesting to evaluate the animals of these lines for productive longevity. In the dairy herd there is a significant number of animals obtained as a result of inbreeding and inbreeding ranges from 0.25±0.026 (Reflection Sovering line) to 0.44±0.038 (Vis Back Ideal line), depending on the line. A greater number of cows obtained as a result of closely related mating in the Vis Back Ideal line. All cows, regardless of their lineage, have a high level of Holstein bloodline from 83.5±2.96 (Montwick Chieftain line) to 87.6±0.51 (Vis Back Ideal line) and, accordingly, can be considered as representatives of the Holstein breed. The highest duration of productive use was found in the group of cows of the Montwick Chieftain line. Lower indicators of productive longevity were found in the group of animals of the Vis Back Ideal line. The age of maximum lactation in the main, most common lines of cows: Reflection Sovering and Vis Back Ideal and amounted to 1.93 and 1.84 lactation, respectively. The most nutrients were obtained from the milk of cows of the Montwick Chieftain line, even for average lactation, which, in our opinion, is explained by the high quality indicators of milk from cows of this group.

Analysis of the relationship between workability traits and functional longevity in Canadian dairy breeds

Simple SummaryLongevity, or the length of a cow’s productive life, is important in terms of profitability, animal welfare and environmental sustainability. In genetic evaluations, interest focuses on functional longevity, defined as a cow’s ability to avoid forced culling, an ability that increases the possibility of voluntary disposal based on economic criteria. Longevity is affected by several non-productive functional traits, among them those related to calving performance: calving ease (dystocia) and perinatal calf mortality (stillbirth). Parturition is a critical event in a cow’s life that has a number of different short- and long-term consequences. In the Polish Holstein-Friesian population, the incidence of dystocia and stillbirth is within the lower range of frequencies found in other dairy cattle populations. Our research showed that both traits affect functional longevity. Difficult calvings occur more frequently in heifers and increase the risk of involuntary culling more than in later parturitions. Additionally, a higher risk of culling is related to birth of a male calf. Moreover, the negative impact of calf mortality on longevity is also more pronounced in primiparous cows and in the case of delivery of male calves. Reducing the incidence of calving problems and perinatal mortality may improve the longevity of dairy cows.Longevity is one of the functional traits that considerably affect dairy herd profitability. A Weibull proportional hazards model was used to evaluate the impact of difficult calvings and calf stillbirths on cow functional longevity, defined as length of productive life corrected for milk production. The data for analysis comprised calving ease and calf mortality scores of 2,163,426 calvings, 34.4% of which came from primiparous cows. The percentage of male calves was 53.4%. Calving ease was scored as “without assistance” (34.44%), “with assistance” (62.03%), “difficult—hard pull” (3.39%), and “very difficult, including caesarean section” (0.14%). Calf mortality scores were “live born” (94.21%) and “stillborn or died within 24 h” (5.79%). The Weibull proportional hazards model included classes of calving ease or calf mortality scores × parity (1, ≥2) × sex of calf as time-dependent fixed effect. The model also included time-dependent fixed effects of year × season, parity × stage of lactation, annual change in herd size, fat yield and protein yield, time-independent fixed effect of age at first calving, and time dependent random herd × year × season. In first-parity cows, very difficult birth of a bull or heifer increased the relative risk of culling, respectively, 2.18 or 1.26 times as compared with calving without assistance. In later parities, the relative risk of culling related to very difficult calving was 2.0 times (for male calves) and 1.33 times (for female calves) higher than the relative risk of culling associated with calving without assistance. Calf mortality showed a negative impact on longevity in both heifers and cows. First-parity stillbirth increased the relative risk of culling depending on sex of calf by 18% in females and by 15% in males; in later parities the increase of the relative risk of culling was lower (by 7% for females, 9% for males). Difficult calvings and their consequences, especially in primiparous cows, may negatively influence dairy herd profitability by reducing the length of cows’ productive life.

An approach to functional longevity in Latxa dairy sheep