Longevity In Dairy Cows Research Articles

Birth Season Affects Cow Longevity

Dairy cow longevity is an important economic trait for producers. In modern dairy farming, longevity of dairy cows is the result of culling decisions, which are determined by several risk factors, including diseases, reproductive and productive performance. Previous studies have documented that seasonal changes affect health, behavior, and performance of dairy cows throughout their life cycle. Increasing cow comfort by making management adjustments to decrease exposure to high temperatures during the hot months give farmers the opportunity to decrease culling risk factors and possibly increase cow productive life. In the present study, we obtained the records of primiparous and multiparous Holstein cows from Florida (n = 10,812) and California (n = 8,197) during a 10-year period (2012–2022). We analyzed the relationship between birth season and longevity (i.e., cows that remained in the herd for 5 or more lactations) in Florida (n = 1,567) and in California (n = 1,669). The number of cows dead, sold, the reasons why they were sold and their relationship with birth season was also analyzed in the Florida data set. The hypothesis is that birth in a cool season will increase the length of herd productive life and decrease the number of cows sold or dead during all lactations. The birth seasons were “cool” (CL; cows born in December, January, February, and March) and “hot” (HS; cows born in June, July, August, and September). Results showed that in Florida, most cows that remained in the herd for more than 5 lactations (i.e., 14.5% of total cow records) were born during CL compared with cows born during HS (1,129, 72% vs 438, 28%; P < 0.01). The same observations were made in California, where greater longevity (i.e., 5 or more lactations, representing 20.4% of total cow records) was attributed to cows born in CL compared with HS cows (939, 56.3% vs 730, 43.7%; P < 0.01). In Florida, a greater number of HS were sold compared with CL cows (765, 52.6% vs 689, 47.4%; P < 0.01). More HS cows were sold due to breeding, feet and leg and mastitis issues in Florida (P < 0.01). Increased cow death during the first 4 lactations was significantly associated with HS (107, 53.8% vs 92, 46.2%; P < 0.01). Results of this study may help farmers create opportunities to make management adjustments related to birth season, or alter negative seasonal factors (i.e., heat stress) to possibly increase cow longevity in dairy herds.

Elucidating the factors and consequences of the severity of rumen acidosis in first-lactation Holstein cows during transition and early lactation.

First-lactation cows are particularly prone to subacute ruminal acidosis (SARA) during transition. Besides common risk factors of SARA, such as feeding of starch-rich diets, an individual severity of SARA in cows has been recently evidenced. Yet, the factors that play a role in SARA severity have not been elucidated. The main goal of this research was to evaluate the factors of SARA severity in first-lactation cows during transition and early lactation, which go beyond high-grain feeding, and to explore their impact on behavior, health, and fermentation in the rumen and hindgut. Twenty-four first-lactation Holstein cows with the same feeding regime were used starting from 3wk before the expected calving day until 10wk postpartum. Cows received a close-up diet (32% concentrate) until calving and were then transitioned to a lactation diet (60% concentrate) within 1 week. The SARA severity was assessed by cluster analysis of several rumen pH metrics, which revealed exceptionally longer and more severe SARA in cows denominated as high (n = 9), as compared to moderate (n = 9) and low (n = 6) SARA severity cows (P < 0.01). The logistic analysis showed that the length of close-up feeding, age at parturition, and the level of dry matter intake (DMI) were the main factors that influenced the cows' odds for high SARA severity (each P ≤ 0.01). Moreover, the ANOVA hinted differences in the metabolic activity of the ruminal microbiome to promote SARA severity, as indicated by highest ruminal propionate proportions (P = 0.05) in high SARA severity cows, also with similar DMI. The distinct SARA severity was marginally reflected in behavior and there were no effects of SARA severity or high-grain feeding on blood inflammation markers, which peaked at parturition regardless of SARA severity (P < 0.01). Still, ongoing high-grain feeding increased liver enzyme concentrations from 6wk postpartum on, compared to weeks before (P < 0.01), yet irrespectively of SARA severity. In conclusion, first-lactation cows differed in SARA severity under the same feeding regime, which was ascribed to management factors and differences in ruminal fermentation. Further research is warranted to validate these findings and to understand the mechanisms behind differences in the metabolic function of rumen microbiome, in particular in terms of evaluating markers for various SARA severity, as well as to evaluate potential long-term effects on health, performance, fertility, and longevity of dairy cows.

Effects of herd management decisions on dairy cow longevity, farm profitability, and emissions of enteric methane – a simulation study of milk and beef production

Sustainable dairy and beef production provides environmental, economic, and social values that can potentially be maximized by optimizing herd management strategies. The length of a dairy cow’s life is affected by, and affects, all three pillars of sustainability. Longevity in dairy cows is multifactorial and strongly dependent on herd management. Despite genetic improvements, the average time of culling for Swedish cows has barely changed and is currently at 2.6 lactations. This culling rate requires a high number of replacement heifers, generating high rearing costs for farmers. This study evaluated different herd management strategies to improve cow longevity and assessed the effects on enteric methane (CH4) emissions from the herd and the profitability of milk production and beef production from the dairy cows and their offspring. The base scenario, an average Swedish Holstein herd of 100 cows, was compared with seven scenarios simulated using a stochastic herd simulation model (SimHerd). Two of these scenarios involved improved health and survival of cows in the herd, three involved improved reproduction, one considered the consequences of keeping all surplus heifers in the herd, and one considered maximizing the use of X-sorted dairy semen and inseminating the rest of the herd with unsorted beef semen, to avoid surplus replacement heifers. Improved fertility had the greatest effect in increasing the productive life per cow, to 3.8 years compared with 2.8 in the base scenario, allowed for more use of beef semen, reduced the number of replacement heifers, and generated the highest herd profit (€98 per cow-year higher than base scenario). Keeping all surplus heifers instead of producing beef × dairy cross calves decreased the number of productive years by 0.8 and reduced profit by €22 per cow-year. The profit was highly associated with costs related to replacement heifers. The highest beef output (3 369 kg per year more than base scenario) was achieved by keeping all heifers and culling a high share of dairy cows, but this scenario also generated much higher enteric CH4 emissions (+1 257 kg per year). Improving health, survival, or fertility reduced enteric CH4 emissions by 90–255 kg per year, while total yearly beef production ranged from 59 kg less to 556 kg more than in the base scenario. Reducing the number of replacement heifers needed by improving cow reproductive performance is thus key to increasing cow longevity and profitability, while reducing enteric CH4 emissions from the herd without compromising milk and meat production.

Dairy cow longevity and farm economic performance: Evidence from Swedish dairy farms

The longevity of dairy cows is mainly determined by farmers' subjective culling decisions and can be linked to the environmental impact of dairy production and to the social acceptance of the industry. Still, the economic impacts of dairy cow longevity are not well understood. The aim of this study was therefore to examine how herd average dairy cow longevity is related to the farm economic outcome. We used 3 indicators of economic outcome: technical efficiency, profitability and average milk yield per cow. We used 2 indicators of dairy cow longevity: average herd length of life and average herd length of productive life. The study was based on a unique and detailed data set from Swedish dairy agriculture, where herd management data from the national dairy herd recording scheme were combined with farm level economic variables, the Swedish farm accountancy survey, for a total of 1,959 observations over the time period 2010 - 2018. The regression results highlight that both measures of average herd dairy cow longevity have an overall positive and statistically significant association with farm level economic performance. These associations had an inverted U-shape which implies that the association is first positive and then declines. Descriptive statistics indicate that the point where the maximum economic performance is attained varied across the economic indicators. Our results are relevant for individual dairy farmers and their advisors who are interested in understanding how herd average longevity relates to economic performance on the farms. Our results are also important from a greater sustainability perspective: linking them to previous knowledge about the positive environmental and social sustainability benefits from keeping cows longer, highlights there may be dairy cow longevity-associated tradeoffs between those benefits and the farm economic outcomes.

Impact of amino acid 233 in Tax on bovine leukemia virus infection in Japanese Black cattle

Bovine leukemia virus (BLV) is an economically important pathogen that both causes fatal enzootic bovine leukosis (EBL) and reduces lifetime milk production, reproductive efficiency, carcass weight, and longevity in dairy cows. The virus can be divided into two categories based on the amino acid at position 233 in Tax protein, which activates viral transcription and probably plays crucial roles in leukemogenesis. We recently reported that early-onset EBL in Japanese Black (JB) cattle was frequently caused by L233-Tax–carrying virus. This study examined the impact of BLV infection, the proviral load (PVL), and amino acid 233 in Tax on the outcomes of JB cattle. We measured PVL in cattle enrolled between February 2016 and December 2018, determined the Tax type of the isolates, and performed follow-up until March 2022. The results demonstrated that BLV infection increased the risk of involuntary culling and mortality in JB cattle in a PVL-dependent manner. Infection with L233-Tax–carrying virus increased the likelihood of mortality by 1.6-fold compared with the effects of P233-Tax–carrying virus infection. Intrauterine and perinatal infections were frequently caused by L233-Tax–carrying virus, and these infections were likely to influence the early onset of EBL in JB cattle. Conversely, breeding cows infected with P233-Tax–carrying virus were often eliminated by involuntary culling. These findings indicate that amino acid 233 in Tax has importance in terms of preventing economic loss attributable to EBL in JB cattle.

Clinical and diagnostic characteristics of the development of hepatocardial syndrome in black and white cows in the early lactation period.

It is known that during the early postpartum and lactation periods in dairy cows, metabolic disorders develop, that is, ketosis, which can lead to secondary damage to internal organs. Therefore, it is important to address the issues of changing the lactating cows' clinical, laboratory, and physiological parameters regarding the development of hepatocardial syndrome. This study aimed to provide clinical and diagnostic justification for developing hepatocardial syndrome in highly productive dairy cows. The study was conducted on 20 black and white cows in the early postpartum period (7-10 days after birth), with a milk production level of >4500 kg of milk during the previous lactation period, a positive result in the formol colloid sedimentary test, the presence of deafness and splitting of heart sounds, changes in the size, or increased pain sensitivity of the percussion field of the liver. Clinically healthy dairy cows in the early postpartum period were used as controls (n = 24). Clinical, electrocardiographic, echocardiographic, and biochemical parameters were also evaluated. Dairy cows with hepatocardial syndrome developed arterial hypertension and sinus tachycardia, which led to a significant decrease in PQ and QT intervals at ECG. A significant increase in the diastolic size of the interventricular septum, systolic size of the free wall of the left ventricle, and diastolic and systolic sizes of the left ventricle and a significant decrease in the shortening fraction of the left ventricular myocardium were observed in the cows due to the development of hepatocardial syndrome. The affected cows demonstrated a significant increase in serum activity of gamma-glutamyl transferase, alanine aminotransferase, lactate dehydrogenase, creatine phosphokinase, alkaline phosphatase, troponin, malondialdehyde, diene conjugates, and ceruloplasmin and a decrease in glucose concentration. In addition, they demonstrated decreased activity of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. Hepatocardial syndrome in dairy cows occurs due to ketosis, characterized by arterial hypertension, sinus tachycardia, a moderate decrease in myocardial contractility, oxidative stress, and cytolysis of cardiomyocytes and hepatocytes. Therefore, the control and prevention of the development of hepatocardial syndrome will make it possible to maintain the productive health and longevity of dairy cows.

Factors affecting true and functional productive lifespan in Italian Holstein-Friesian cows

The identification of factors affecting longevity in dairy cows is of great importance to improve their length of productive life. Cows can be replaced for poor milk production (i.e. true productive lifespan, TPL) or other reasons than production (functional productive lifespan, FPL). The objective of the present study was to investigate the influence of milk yield, fat and protein contents, insemination status (INS), somatic cell count (SCC) and β-hydroxybutyrate (BHB) concentration in milk on TPL and FPL. Data included 70,748 Italian Holstein-Friesian cows that calved for the first time between 2014 and 2018. Proportional hazards models assuming a piecewise Weibull distribution of the baseline hazard function, with or without adjustment for milk production, were used to compute relative risks of culling associated with FPL and TPL, respectively. Our study revealed that milk yield, protein and fat contents, INS, SCC and concentration of BHB in milk exhibited significant relationships with TPL and FPL. In particular, the huge difference in risk ratios between high- and low-producing cows confirms the central role of milk production in culling decision-making. In addition, farmers appear more prone to cull cows with several events of high SCC and BHB concentration in milk. HIGHLIGHTS Milk yield, fat and protein contents, insemination status, somatic cell count and ketosis affect productive lifespan in Italian Holstein cows. These factors, therefore, contribute significantly to culling decisions. The identified risk factors of culling can be exploited to improve the current management practices in Italian Holstein Friesian herds and cows’ longevity.

Analysis of Longevity Traits in Holstein Cattle: A Review.

Dairy cow longevity is an essential economic trait that can supplement the breeding value of production traits, which is related to the herd time and lifetime milk yield of dairy cows. However, longevity is a relatively difficult trait to select for dairy cow breeding due to low heritability and numerous influence factors of the longevity in dairy cows. Longevity trait has been used as an important breeding target of a comprehensive selection index in many dairy developed countries; however, it has not been included in performance index in many developing countries. At present, cows in these countries are still in the primary stage of “large quantity, low quality, high cost, and low yield.” The average parity of dairy cows is less than 2.7, which is difficult to maintain the production efficiency to meet the demands of the dairy industry. Therefore, there is an urgent need to select and breed for the longevity of dairy cows. The various definitions and models (including linear, threshold, random regression, sire, and survival analysis) of longevity were reviewed and standardized. Survival analysis is the optimal model to evaluate longevity, and the longevity heritability is 0.01–0.30 by using different definitions and models. Additionally, the relationship between longevity and other traits was summarized, and found that longevity was regulated by multiple factors, and there were low or medium genetic correlations between them. Conformation traits, milk production traits, reproductive traits, and health traits may be used as indicators to select and breed the longevity of dairy cows. The genetic assessment methods, heritability, influencing factors, importance, breeding, and genetics of longevity were reviewed in the manuscript, which could provide a valuable reference for the selective breeding to extend the productive life of Holstein cattle.

An Empirical Analysis on the Longevity of Dairy Cows in Relation to Economic Herd Performance.

Several studies have stated the various effects of an increased dairy cow longevity on economic herd performance, but empirical studies are lacking. This study aimed to investigate the association between longevity of dairy cows and the economic performance of dairy herds based on longitudinal Dutch accounting data. Herd and farm accounting data (n = 855 herds) over the years 2007–2016 were analyzed. Herd data contained yearly averages on longevity features, herd size and several production variables. Longevity was defined as the age of cows at culling and by lifetime milk production of culled cows. Farm accounting data contained yearly averages on revenues, fixed and variable costs of the herds, by which gross margins were defined. Data was analyzed using generalized linear mixed modeling, with gross margin as dependent variable. The independent variables consisted of average age of culled cows, average lifetime production of culled cows, year, herd size, herd intensity (milk production per ha), herd expansion rate, soil type, milking system, successor availability, total full-time equivalent, heifer ratio (% of heifers per cow) and use of outsourced heifer rearing. Herd was included as a random effect to account for the heterogeneity among herds. Descriptive statistics showed that the average age of culled cows was 5.87 (STD = 0.78) years and the average lifetime milk production of culled cows was 31.87 (STD = 7.56) tons per cow with an average herd size of 89 cows (STD = 38.85). The average age of culled cows was stable over the 10 years (variation between 5.79 AND 5.90 years). The gross margin was on average €24.80/100 kg milk (STD = 4.67), with the lowest value in year 2009 and the highest value in year 2013. Gross margin was not significantly associated with age of culled cows and lifetime milk production of culled cows. Variance in longevity between herds was large (STD = 0.78 years) but herds with a higher longevity did not perform economically better nor worse than herds resulting in lower longevity. This indicates that, within current practice, there is potential for improving longevity in order to meet society's concerns on animal welfare and environmental pollution, without affecting the economic performance of the herd.

Prenatal programming of later performance in dairy cattle

Prenatal programming refers to the fact that insults during pre- and early postnatal life can have long-term consequences on the health and performance. In diary cattle, physiological conditions, such as maternal body growth, milk yield and parity, and environmental conditions during gestation can create a suboptimal environment for the developing fetus. As a consequence, adaptations of the placental and newborn phenotype take place. In addition, potential long-term effects of prenatal programming influence body growth, fertility, milk yield and longevity in dairy cows. These results suggest that the current management systems may pose a risk for the long-term health and performance of dairy cattle. Hence, in management practices, all pre- and postnatal aspects should carefully be considered in order to raise healthier and more productive dairy cows.

Longevity of dairy cows — energy profile

Longevity of dairy cows — energy profile

Physiology and endocrinology symposium: Anti-Müllerian hormone: a biomarker for the ovarian reserve, ovarian function, and fertility in dairy cows.

This review summarizes studies we conducted to test the hypothesis that size of the ovarian reserve (number of healthy follicles and oocytes in ovaries) positively impacts ovarian function and fertility in cattle. Key results, primarily in Bos taurus dairy cattle, show that antral follicle count (AFC) during follicular waves is highly variable between individuals, but very highly repeatable within individuals. Cycling heifers with low (≤15 follicles ≥3 mm, ~20% of a herd) vs. a high AFC (≥25, ~20% of a herd) have a smaller ovarian reserve, higher FSH but lower anti-Müllerian hormone (AMH), androstenedione, estradiol, and progesterone concentrations. Moreover, cattle with low AFC have a thinner endometrium, decreased response of granulosal, thecal, or luteal cells to FSH or LH and a poorer response to superovulation compared to cattle with high AFC. Interestingly, cows with a very high AFC as heifers have reduced fertility, fewer lactations, and shorter herd longevity, whereas cows with a low vs. intermediate AFC have reduced fertility, fewer lactations, and shorter herd longevity. Anti-Müllerian hormone concentrations are static within individuals but highly positively correlated with AFC, but fertility is not correlated with circulating AMH concentration in heifers and dairy cows with low vs. a higher AMH as heifers have reduced fertility and a shorter herd longevity. Anti-Müllerian hormone concentrations in dairy heifers are a moderately heritable trait (36%), and negatively impacted by inadequate maternal nutrition during early pregnancy or high maternal somatic cell count. We conclude that genetic or environmental manipulations of AMH could enhance size of the ovarian reserve and ovarian function, thereby improving fertility, response to superovulation, and longevity in dairy cows.

Effect of Age at First Calving on First Lactation Milk Yield, Lifetime Milk Production And Longevity of Cows

Abstract The objective of the study was to analyse the effect of age at first calving (AFC) on first lactation milk yield, lifetime milk production and longevity of dairy cows. The study used SYMLEK data on the milk yield and culling of 111 857 Polish Holstein-Friesian cows from the active population in Pomerania and Kujawy, Poland. The cows first calved during 2000–2009 and were used or removed from the herds until the end of 2015. For each cow, calculations were made of first lactation milk yield, lifetime milk production, first lactation milk yield per milking day, lifetime milk production per day, as well as the lifespan (length of productive life, duration of rearing) and number of calvings. Based on the age at first calving (duration of the rearing period), the cows were grouped as follows: ≤22, 22.1–24.0, 24.1–26.0, 26.1–28.0, 28.1–30.0, 30.1–32.0 and &gt;32 months. The GLM, CORR PEARSON and FREQ procedures from the SAS package were used in the statistical calculations. Considering first lactation milk yield, lifetime milk production and longevity, it is recommended that the cows should be first milked between 22.1 and 26.0 months of age. This is supported by the approximately 24% higher lifetime milk production in relation to the latest calving cows (P&lt;0.01). Late commencement of the first milking (especially after 28 months) causes a considerable decrease in the first lactation milk yield and lifetime milk production, shortens the productive period, reduces the number of calvings, and increases culling rate due to low milk yield and udder diseases.

Effect of two housing systems on performance and longevity of dairy cows in Northern Italy

Effect of two housing systems on performance and longevity of dairy cows in Northern Italy

125 Anti-Müllerian Hormone (AMH): a biomarker for the ovarian reserve, ovarian function and fertility in dairy cows.

This presentation summarizes studies we conducted to test the hypothesis that size of the ovarian reserve (number of healthy follicles and oocytes in ovaries) positively impacts ovarian function and fertility in cattle. Key results primarily in dairy cattle show: 1) Antral follicle count (AFC) during follicular waves is highly variable between individuals but very highly repeatable within individuals. 2) Cycling heifers with low (≤ 15 follicles ≥3 mm, ~20% of a herd) vs a high (≥25 AFC, ~20% of a herd) have: i) a smaller ovarian reserve; ii) higher FSH but lower AMH, androstenedione, estradiol and progesterone concentrations and a thinner endometrium; iii) decreased response of granulosal, thecal or luteal cells to FSH or LH; and iv) a poorer response to superovulation. 3) Cows with a very high AFC as heifers have reduced fertility, fewer lactations and shorter herd longevity. 4) Cows with a low vs intermediate AFC have reduced fertility, fewer lactations and shorter herd longevity. 5) AMH concentrations are static within individuals but highly positively correlated with AFC. 6) A single AMH measurement is highly positive correlated with the average of multiple AMH measurements on different days of the cycle and AFC. 7) Fertility is not correlated with circulating AMH concentration in heifers. 8) Dairy cows with low vs a higher AMH as heifers have reduced fertility and a shorter herd longevity. 9) AMH concentrations in dairy heifers is a moderately heritable trait (36%), and negatively impacted by inadequate maternal nutrition during early pregnancy or high maternal somatic cell count. We conclude that genetic or environmental manipulations of AMH could enhance size of the ovarian reserve and ovarian function, thereby improving fertility, response to superovulation and longevity in dairy cows. Research support: NRI Grants no. 2004-35203-14781 and 2007-35203-18178; AFRI Grants 2013-67015-20962; MSU’s AgBioResearch; and Green Meadow Farms, Inc.

Analysis of Lifetime Performance and Culling Reasons in Black-and-White Holstein-Friesian Cows Compared with Crossbreds

Abstract The effect of crossbreeding Holstein-Friesian cows with other breeds is usually improved genetic potential of crossbreds in terms of longevity. However, culling decisions, which in practice determine the longevity in dairy cows, are contingent on many environmental and economic factors. Therefore, the aim of this study was to evaluate longevity in relation to culling reasons in Holstein-Friesian cows of the Black-and-White strain (HO) and crossbreds, taking genotype, age at first calving, herd size, culling season, culling reason and milking temperament into consideration. The data analysed concerned 154,256 dairy cows culled in Poland in 2015. It was found that all studied factors significantly affected cow lifetime performance. The mean age at culling in dairy cows of HO strain exceeded 6 years, with mean lifetime energy-corrected milk (LECM) yield of 28,933 kg and mean lifetime energy-corrected milk yield per milking day (DECM) of 20.2 kg. Crossbreds, on the other hand, tended to have shorter lifespans, with mean LECM yield amounting to less than 25,000 kg. Mean LECM yield of cows surviving for the longest period (9.2 years), amounted to 47,771 kg, and reproduction problems were unquestionably the most common (40%) reason for cows’ culling. A suggestion was made to take milking temperament into account in breeding practice, as this trait proves to be closely related to the longevity characteristics of dairy cows. It was also proposed that the culling reasons be subjected to a more comprehensive analysis, considering the “life history” of cows as well as the interactions between different reasons for their removal from the herd.

Productive longevity of cows of dairy breeds depending on the duration of their first service period

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%.

Phenotypic and genetic relationships between age at first calving, its component traits, and survival of heifers up to second calving

The aim of this study was to answer the question whether models for genetic evaluations of longevity should include a correction for age at first calving (AFC). For this purpose, phenotypic and genetic relationships between AFC, its component traits age at first insemination (AFI) and interval from first to last insemination (FLI), and survival of different periods of the first lactation (S1: 0 to 49 d, S2: 50 to 249 d, S3: 250 d to second calving) were investigated. Data of 721,919 German Holstein heifers, being inseminated for the first time during the years from 2003 to 2012, were used for the analyses. Phenotypic correlations of AFI, FLI, and AFC to S1 to S3 were negative. Mean estimated heritabilities were 0.239 (AFI), 0.007 (FLI), and 0.103 (AFC) and 0.023 (S1), 0.016 (S2), and 0.028 (S3) on the observed scale. The genetic correlation between AFI and FLI was close to zero. Genetic correlations between AFI and the survival traits were -0.08 (S1), -0.02 (S2), and -0.10 (S3); those between FLI and the survival traits were -0.14 (S1), -0.20 (S2), and -0.44 (S3); and those between AFC and the survival traits were -0.09 (S1), -0.06 (S2), and -0.20 (S3). Some of these genetic correlations were different from zero, which suggests that correcting for AFC in genetic evaluations for longevity in dairy cows might remove functional genetic variance and should be reconsidered.

Metabolic adaptation recorded during one lactation does not allow predicting longevity in dairy cows.

Metabolic and health disorders account distinctly for culling in dairy cows. This study investigated if metabolic status obtained once in life during a negative energy balance in early lactation allows to predict age and lifetime performance animals achieved at culling. Metabolically stressed cows entering at least their 3rd lactation (n = 200, parity: 5.0 ± 2.1, mean ± SD) were selected from a field study conducted in Switzerland. Age of cows at culling ranged from 4.7 to 20.2 years with parities from 3 to 17. From cows with known reasons of culling, 28.4% were culled because of fertility, 16.4% due to udder health, 15.5% due to high age and 10.4% because of claw health/lameness. A retrospective classification of the one-time recorded metabolic adaptation in week 4 post partum did not differ between animals of different parities at culling. Furthermore, there was no relationship neither between the metabolic adaptation recorded in a preceding lactation and the number of lactations achieved, nor to the lifetime milk production. Contrary to the wide spread assumptions, an inadequate adaptation due to a high metabolic load in early lactation may not result in an earlier culling of dairy cows, although they are more prone to metabolic disorders.

Effect of dystocia on subsequent reproductive performance and functional longevity in Holstein cows.

The objective of this study was to evaluate the effect of dystocia on the reproductive performance and functional longevity in Iranian Holsteins. Data consisted of 1467064 lactation records of 581421 Holstein cows from 3083 herds which were collected by the Animal Breeding Center of Iran from April 1987 to February 2014. Reproduction traits in this study included interval from first to second calving, days open and days from first calving to first service. The generalized linear model was used for the statistical analysis of reproductive traits. Survival analysis was performed using the Weibull proportional hazards models to analyse the impact of dystocia on functional longevity. The incidence of dystocia had an adverse effect on the reproductive performance of dairy cows. Therefore, reproductive traits deteriorated along with increase in dystocia score (p<0.05). The culling risk was increased along with increase in the score of dystocia (p<0.0001). The greatest culling risk was observed in primiparous cows, small herds and low-yielding cows (p<0.0001). Also, the lowest culling risk was found for cows calving at the youngest age (<27months), and cows with age at first calving >33months had the greatest risk (p<0.0001). The results of current study indicated that dystocia had important negative effects on the reproductive performance and functional longevity in dairy cows, and it should be avoided as much as possible to provide a good perspective in the scope of economic and animal welfare issues in dairy herds.