Genetic Potential For Milk Production Research Articles

Review and analysis on fertility and milk production in commercial dairy farms with customized lactation length during the last ten years

Approximately 150 million households around the globe are engaged in milk production. In most developing countries, milk is produced by smallholders, and milk production contributes to household livelihoods, food security and nutrition. Milk provides relatively quick returns for small-scale producers and is an important source of cash income. In recent decades, developing countries have increased their share in global dairy production. This growth is mostly the result of an increase in numbers of producing animals rather than a rise in productivity per head. In many developing countries, dairy productivity is constrained by poor-quality feed resources, diseases, limited access to markets and services (e.g., health, credit and training) and dairy animals’ low genetic potential for milk production. Unlike developed countries, many developing countries have hot and/or humid climates that are unfavourable for dairying. Traditionally, dairy farmers are recommended to aim for a 1-yr calving interval, as this would maximize milk production and income. Longer calving intervals would extend the period in late lactation, when milk production is lower. However, there may be several reasons to re-evaluate the traditional lactation length, including increased productivity of modern dairy cows, and potential benefits of longer lactations for cow health and welfare. Moreover, although farmers are advised to aim for a 1-yr calving interval, in practice calving intervals mostly exceed 1 yr. Some cows might be better suited for an extended CInt than others, due to differences in milk yield level, lactation persistency, or health status, which would justify a customized CInt based on individual cow characteristics. This study aims to investigate 13 farms with customized CInt, with respect to calving to first service interval (CFSI), accomplished CInt, services per conception (SC), conception rate at first artificial insemination (CR1AI), peak yield, lactation persistency, 305-d yield, and effective lactation yield. In total, 4,858 complete lactations of Holstein Friesian cows between 2012 and 2022 from the 13 farms were grouped by parity and CFSI or CInt.

Estimates of genetic parameters for production and reproduction traits in Murrah buffaloes (Riverine buffalo) in India

Murrah is a predominant milch breed of buffalo in India with superior genetic potential for milk production. Estimation of genetic parameters for production and reproduction traits is prerequisite for making breeding plan and efficient management decisions. This work was undertaken to understand the influence on performance traits by various factors (genetic and non-genetic) along with assessment of genetic parameters in Murrah buffaloes. The genetic parameters were figured using mixed model least-squares analysis. The results revealed that season and period in which animals calved, affects the performance of Murrah breed and may be considered during its evaluation. The heritability estimates for first lactation 305 days/less milk yield (305FLMY), first lactation total milk yield (FLTMY), first Lactation Length (FLL1), Wet average (WA), Herd average (HA), Age at first calving (AFC1) and Age at first service (AFS1) were 0.39±0.10, 0.29±0.09, 0.14±0.09, 0.29±0.09, 0.3±0.11, 0.27±0.09 and 0.22±0.09, respectively. The phenotypic and genetic correlation amid 305FLMY and majority of another production trait were positive and significant. Thus, it may be concluded that appropriate estimation of genetic parameters leads to robust selection for performance traits for genetic improvement in Murrah buffalo.

Relación del calcio, fósforo, magnesio y selenio sobre la reproducción en vacas lecheras durante el periodo de transición

The transition period is a stage of significant hormonal and metabolic changes as it goes from a period of fat deposition during late pregnancy to one of tissue mobilization prior to the beginning of lactation. The transition period (three weeks before and three after calving) is a dramatic change for the animal, where the greatest energy and metabolic imbalances occur. During early lactation, lipolytic activity increases in the dairy cow, since the degree of lipolysis depends on the genetic potential for milk production and the severity of the negative energy balance (NEB). Most dairy cow mineral disorders occur in the peripartum and are directly related to nutritional management during the dry period, particularly in the last weeks before calving. It has been found that the lack or imbalance of minerals in the soil is reflected in the nutritional value of the pastures and this is one of the causes of the low productivity and reproductive problems of cattle; This is manifested in a conception rate of no more than 45%, a percentage of abortions that can reach 10% and an age and weight at the first service and at the first delivery that are outside the efficient values for a productive livestock.

Glucose metabolism and the somatotropic axis in dairy cows after abomasal infusion of essential fatty acids together with conjugated linoleic acid during late gestation and early lactation

Sufficient glucose availability is crucial for exploiting the genetic potential of milk production during early lactation, and endocrine changes are mainly related to repartitioning of nutrient supplies toward the mammary gland. Long-chain fatty acids, such as essential fatty acids (EFA) and conjugated linoleic acid (CLA), have the potential to improve negative energy balance and modify endocrine changes. In the present study, the hypothesis that combined CLA and EFA treatment supports glucose metabolism around the time of calving and stimulates insulin action and the somatotropic axis in cows in an additive manner was tested. Rumen-cannulated German Holstein cows (n = 40) were investigated from wk 9 antepartum (AP) until wk 9 postpartum (PP). The cows were abomasally supplemented with coconut oil (CTRL, 76 g/d); 78 g/d of linseed and 4 g/d of safflower oil (EFA); Lutalin (CLA, isomers cis-9,trans-11 and trans-10,cis-12 CLA, each 10 g/d); or the combination of EFA+CLA. Blood samples were collected several times AP and PP to determine the concentrations of plasma metabolites and hormones related to glucose metabolism and the somatotropic axis. Liver tissue samples were collected several days AP and PP to measure glycogen concentration and the mRNA abundance of genes related to gluconeogenesis and the somatotropic axis. On d 28 AP and 21 PP, endogenous glucose production (eGP) and glucose oxidation (GOx) were measured via tracer technique. The concentration of plasma glucose was higher in CLA than in non-CLA-treated cows, and the plasma β-hydroxybutyrate concentration was higher in EFA than in non-EFA cows on d 21 PP. The eGP increased from AP to PP with elevated eGP in EFA and decreased eGP in CLA-treated cows; GOx was lower in CLA than in CTRL on d 21 PP. The plasma insulin concentration decreased after calving in all groups and was higher in CLA than in non-CLA cows at several time points. Plasma glucagon and cortisol concentrations on d 21 PP were lower in CLA than non-CLA groups. The glucagon/insulin and glucose/insulin ratios were higher in CTRL than in CLA group during the transition period. Plasma IGF-I concentration was lower in EFA than non-EFA cows on d 42 AP and was higher during the dry period and early lactation in CLA than in non-CLA cows. The IGF binding protein (IGFBP)-3/-2 ratio in blood plasma was higher in CLA than in non-CLA cows. Hepatic glycogen concentration on d 28 PP was higher, but the mRNA abundance of PC and IGFBP2 was lower in CLA than non-CLA cows on d 1 PP. The EFA treatment decreased the mRNA abundance of IGFBP3 AP and PCK1, PCK2, G6PC, PCCA, HMGCS2, IGFBP2, and INSR at several time points PP. Results indicated elevated concentrations of plasma glucose and insulin along with the stimulation of the somatotropic axis in cows treated with CLA, whereas EFA treatment stimulated eGP but not mRNA abundance related to eGP PP. The systemic effects of the combined EFA+CLA treatment were very similar to those of CLA treatment, but the effects on hepatic gene expression partially corresponded to those of EFA treatment.

The Influence of Essential oils Supplementation on Yield and Quality of Sheep milk

Throughout the world major proportion of milk is obtained from large dairy animals, cows and buffaloes, however there is a considerable proportion of milk yield obtained from small dairy animals, sheep and goats. The share of milk production by sheep in total milk yield of the world is small because of different breeds having different genetic potential of milk production, managemental factors, environmental factors, nutritive factors, etc. The sheep milk is important because of cheese making. Due to microbial resistance, risk of drug residues either in milk, meat, or in eggs are dangerous for humans beings. So therefore the use of these synthetic compounds to improve immunity, health (antibiotics are used for growth promotion), and productivity (hormones are used to boost the milk production) in dairy animals is discouraged and the European Union has banned the use of these synthetic compunds in animals. So the phytobioactive compounds, essential oils, are used in feeds or rations of dairy animals to increase their production. These compounds are added not only to improve the milk yield but also to improve fat, protein and lactose contents of milk. The essential oils added in the diets of small dairy animals are usefull to counter the negative energy balance as well as the fatty acid profie to increase the quality of sheep milk. Key words: Sheep milk, essential oils, milk yield DOI: 10.7176/JSTR/7-01-03

Pasture-Based Dairy Systems in Temperate Lowlands: Challenges and Opportunities for the Future

Improved efficiency in dairy systems is a significant challenge for the future, to meet increased food demand while competing for inputs, adapting to climate change, and delivering ecosystem services. Future grazing systems can play a major role to supply healthier foods within systems with a reduced reliance on fossil fuels and chemical inputs, while also delivering environmental, biodiversity, and animal welfare benefits. Can we design lower-input systems that deliver efficient levels of output in a positive environmental context? Lower-input systems will have a lower reliance on concentrates and inorganic fertilizers, and an increased reliance on extended grazing seasons and high quality forage. Multiple strategies will be needed to maximize nitrogen use efficiency, including a strong reliance on legume-based swards that displace inorganic nitrogen fertilizer. Expected environmental benefits include a reduction in GHG emissions and nitrate leaching, an increase in C sequestration and a reduced reliance on the use of herbicides and pesticides. In comparison with confinement feeding systems, the relatively low energy density and high climate sensitivity of grazing diets requires both effective pasture management and robust and adaptive animals. The appropriate cow for grazing systems must be able to harvest pasture efficiently by re-calving every 365 days to efficiently utilize peak pasture supply, achieve large intakes of forage relative to their genetic potential for milk production (i.e., aggressive grazers) and be adaptable to fluctuations in feed supply. Legume-based multi-species grassland mixtures can maximize the use of symbiotically-fixed nitrogen, and displace the use of inorganic N fertilizer. There is a need for system-scale experiments that use legume-based mixtures within paddocks, and in grassland leys within crop rotations. Moreover, lower-input systems will need a combined focus on research and knowledge transfer for rapid testing and implementation. New opportunities and requirements will arise as policy, society, and the markets demand a higher level of environmental sustainability from food systems and products. This raises the possibility of public-private partnerships for the demand and reward of provision of environmental benefits. To deliver these benefits, future food systems will need to be redesigned to incorporate the enhanced supply of a range of ecosystem goods and services, which should be better incentivized through the market price returned to producers.

Productive and reproductive performance of females F1 Holstein x Gir daughters of proven bulls.

Records of 234 lactations from F1 Holstein x Gyr daughters of proven bulls were used in this study for the evaluation of productive and reproductive characteristics of cows. Data were collected from a private farm located in the municipality of Santo Antônio do Monte, MG, Brazil. The objective of this study was to evaluate the effects of Holstein bull's PTA milk (predicted transmitting ability) calving year, season, and parity on the productive and reproductive characteristics of F! cows. The productive characteristics analyzed were total milk production (TMP), average daily production (ADP), days in milk (DIM), and milk yield per day of calving interval (MYDCI). The studied reproductive characteristics were service interval (SI), calving interval (CI), and gestation length (GL). The results were subjected to statistical analysis and means for significant effects were compared using Duncan's test at a significance level of 5%. F1 animals efficiently expressed their genetic potential for milk production with an average total milk production of 7842.61kg and average daily production of 24.53kg. Means for days in milk, milk yield per day of calving interval, service interval, calving interval, and gestation length were 322.52days, 20.73kg, 106.0days, 383.23days, and 276.18days, respectively. Properly managed F1 Holstein x Gyr daughters of proven bulls fed a balanced diet efficiently expressed their genetic potential for milk production without adverse effects on reproduction. Moreover, Holstein x Gyr cows should be selected based on parents' PTA for milk traits and other factors such as environmental conditions and management.

APPLICATION OF THE DESIRED TYPE CONCEPT IN HERD OF JERSEY BREED

The results of the studies highlight the usefulness of application of the concept of the desired type for herd of Jersey breed. The researches have conducted in the herd of the Jersey breed of «Dan-Milk» subsidiary of Chernyakhiv district of Zhytomyr region. Zootechnical and breeding records have been established at a high level. The implementation of various zootechnical and technological operations greatly facilitate by the introduction of the automated information system "Uniform Agri". The conditions for raising, feeding, keeping and using cows ensure the realization of their genetic potential for milk production.
 Milking of cows held on the "Parallel". Keeping cows unattached to rest boxes. The rations have made according to the physiological state and the level of productivity of the animals.
 The correspondence of the indices of first-calf cows of cognate groups, offspring of booger-breeders, differentiated groups by the value of the animals of the desired type was determined by the mean normalized deviation (t) in fractions of the mean square deviation (σ) according to the concept of the desired type by the method of M. Pelekhaty and L. Piddubna. The cows were characterized by 6 indicators of dairy productivity and 5 – reproductive ability of the first lactation.
 Improving the economically useful traits of cows to parameters of the desired type were carried out by using various breeding techniques. The offspring of bulls Headline 114114336 (t = -0.27) and DJ Jante 302761 (t = -0.30) had the best fit for the parameters of animals of the desired type according to the studied characteristics, the worst was Karl 67037285 (t = -0.77).
 As a result of researches it has been established that indices of cows of different cognate groups have characterized by less conformity to parameters of animals of the desired type, in comparison with the results of daughters of individual sires on the average value of normalized deviation. Cows of the Fallneva’s 593883 (+0.01) cognate group are closer in terms of reproducibility to animals of the desired type of cows, Surville’s 604694 (-0.06) are the least, and in the milk productivity, the Observer’s 553236 (-0.56) related group and Fallneva’s 593883 (-0.82), respectively.
 With the increase in the milk yield of Jersey cows, there was a decrease in the difference between the indices of animals of different groups with corresponding parameters of animals of the desired type. With the increase in the level of milking from 10 thousand. slightly better cows (t = +0.06) have observed for the parameters of the animals of the desired type, but this result is due to the very low reproductive ability of the cows and long lactation, which makes it impossible to repair the herd in time for its own young.
 In 36 cases out of the 55 cows with different levels of dairy productivity were significantly inferior to parameters of the animals of the desired type, accounting for 65.5% of the total number of comparisons. It is advisable to select animals with a milk yield of at least 9000 kg of milk, which will lead to an increase in the number of cows of the desired type in the herd.
 The most usefulness methods of creating a high-performance dairy herd for «Dan-Milk» subsidiary have been identified and presented. They identified the use of Jersey sires cows and the selection of cows by milk yield (the average normalized deviation on reproduction ability were -0.07 and -0.08, on the basis of dairy productivity -0.73 and -0.72).

QUALITY OF MILK PRODUCTION OF THE HOLSTEIN COWS DEPENDING ON DIFFERENT FACTORS

Studies have revealed that despite the selection, the Holstein cows have a high genetic potential of milk production and in all lactations it is good in the specific conditions of the hot climate of Uzbekistan. The milk production level of German cows for the first lactation was 6511.2 kg of milk with a fat content of 3.84%, the Dutch — 6653.0 kg with fat content of 3.95%, and local breed — 6495.2 kg with a fat content of 3.95%. All mature cows retained high milk production, for III lactation and older it was 7112.5 kg and 3.90%, 7266.0 kg and 3.90%, 6847.5 kg and 3.94%, respectively. The yield of Dutch breeding cows was higher for 1 lactation by 141.80–157.8 kg, for III lactation and older by 153.5–418.5 kg, the yield of milk fat by 12.8–6.3 kg, respectively, of indicators peers of German and local selection. The cows of the studied selections combined well with high milk yield and fat content. The level of 4% milk for the studied lactation in all cows was quite high and testified to its good nutritional value. Holstein cows of different breeds are distinguished by a strong dairy type. For I lactation, for every 100 kg of live weight, 1,159.0–1265.5 kg of milk was produced, for III lactation and older - 1200.0–1308.6 kg. It is revealed that milk productivity depends on the level of live weight of cows. The increase in body weight of cows in all groups provides an increase in milk yield, milk fat yield, milk yield of 4% milk. Milk productivity is interrelated with the duration of the service period. In group I, cows with a service period of 91–100 days were more productive, in group II, 81–90 and in group III, up to 80 days. The use of Holstein cows for the production of milk is effective and ensures an increase in its production, the creation of highly productive dairy herds and the production of high-quality maintenance stock. KEYWORDS: Holstein breed, herd, milk yield, milk, fat, selection.

Молочна продуктивність різновікових голштинських корів за подовженої лактаційної функції

Presented study results of the productivity of mixed-aged cows with prolonged lactation. The formation of experimental groups was carried out according to the principle of analog groups, taking into account breed, live weight, age and physiological condition (lactation):25 animals in groups I, II, III and IV and 10 animals in group V. It was found that with the industrial technology of Holstein cows exploitation, regardless of their age, the duration of the lactation period was almost twice as long as the scientifically substantiated value and ranges from 561.2 to 610.9 days. At the same time, the milk productivity level of the cows in I and IV groups slightly exceeded 13 000 kg of milk per lactation, while in cows if II, III (control), and V groups – this value was higher than 15 000 kg. With prolonged lactation, the milk yield in the experimental groups of animals in terms of 305 days was kept at a fairly high level and there was a definite tendency to an increase in milk yield depending on the age of the animals. The first-calf heifers of group I were characterized by a relatively low milk yield since they gave only 13 291.8 kg of milk for the entire lactation, and in terms of 305 days – 7 944.1 kg, which was 13.57% and compared to III (control) group was 19.54% lower (P < 0.01). Animals of the fifth lactation from group V had the highest milk yield, in which the milk yield per lactation and per 305 days amounted to 15 818.5 kg and 9 716.7 kg of milk, respectively. With intensive exploitation technology and with the increasing age of Holstein cows, complete adaptation occurs, as a result of which their genetic potential for milk production is realized at a high level. This was indicated by the milk yield dynamics in experimental animals of different ages, in which, under the same conditions of feeding and housing, they were gradually increased from the first to the fifth lactation.

ИННОВАЦИОННЫЙ МЕТОД ЛЕЧЕНИЯ КОРОВ ПРИ МАСТИТЕ

In the modern world of agriculture, which is directly related to the breeding of cattle, aimed in particular at milk production, the problem associated with inflammation of the udder lobes, namely mastitis, has become widespread. To a large extent, the culling of cows occurs due to the inability to completely and completely cure this disease without damaging the productivity in the herd, as well as due to complications caused as a result of the transferred inflammation (atrophy, induration, fibrosis of the udder lobes). Mostly young animals with a high genetic potential for milk production suffer from this pathology. According to statistical data, namely, in 20%-30% of cases, subclinical mastitis enters the clinical phase with a pronounced symptomatic form of lesion of the udder lobes, which in the future can lead to their atrophy and other irreversible complications. The main symptomatic signs of the general condition of an animal with a pronounced clinical form of mastitis are: the apathetic state of the animal and refusal to feed due to an increase in the general body temperature, depending on the nature of the course and the form of the disease. When considering the same pathology of its symptoms, on the basis of local signs of the course, I single out a complex of symptoms that is observed in almost all forms of udder lesions: an increase in the local temperature of the mammary gland, hyperemia and swelling of the affected lobes of the udder, or the entire organ with generalization of inflammation in all lobes, in a clinical study , namely, on palpation in the animal, a painful reaction is observed, a change in the consistency of the udder and nipples, as well as an increase and compaction of the supra-lymph nodes. When considering the economic damage on farms associated with the presence of mastitis in productive animals, there is not only a general decrease in the overall productivity of the dairy herd, which is associated with the loss of milk at production, but also with a decrease in milk yield in individual animals associated with dysfunction of the mammary gland due to the presence of impurities and inhibiting substances throughout the treatment and sometime after it. As a percentage of milk yield per lactation in cows that have undergone subclinical mastitis, there is a decrease in milk production by 10-15%, while a deterioration in the quality characteristics of products is also observed. Early diagnosis, timely treatment and prevention of subclinical mastitis is an urgent task. The main purpose of this article is the need to consider an increase in the effectiveness in the treatment of mastitis, according to the method of using the means of complex etiotropic therapy, by means of which the absence of inhibitory substances in milk will be ensured and will allow the sale of these products in the future without restrictions, as well as an increase in the economic well-being of farms, including treatment costs.

FERTILITY AND PRODUCTIVITY OF FIRST-CALF COWS OF UKRAINIAN BLACK-AND-WHITE DAIRY BREED

The selection of animals at the lowest number of indicators is more effective compared to selection on many grounds. The main focus during the selection of Holstein cattle was to increase milk productivity, which meant the neglect of other important features, such as fertility (fecundity) of animals.
 The purpose of the work was to determine the level of milk productivity of cows of Ukrainian Black-and-White dairy breed in conditions of a particular farm, in which there would be a successful combination of reproductive capacity support for adjusting the selection of animals.
 The research was carried out in the breeding plant of the Ukrainian Black-and-White dairy breed of farm "Khliborob" of Kozyatinsky district of Vinnytsia region. The material of the research was the information of 212 first-calf cows of Ukrainian Black-and-White dairy breed of this farm.
 Indicators of dairy productivity were studied in 305 days of lactation according to zootechnical records.
 Reproductive ability of cows evaluated index insemination, age 1 st calving (months), duration (days) of service period, the period of pregnancy, the period between calving, the dry period, a rate of reproductive capacity (CRF), the calves are emitted per 100 cows (%) and the fertility index.
 The first-breed differentiation was carried out at a deviation of 0.7 σ from the mean of index (M) of the fertility index. Such a division makes it possible to divide the herd into 3 groups in a ratio of 1:2:1.
 The highest level of dairy productivity have characterized by animals of the I group with low fertility (the fertility index was on average 40.8), which significantly surpassed their peers of the III group with good fertility for the livelihood for 305 days of lactation for 434 kg, milk protein production – by 15.2 kg, total milk fat and protein production – by 26.0 kg (P ≤ 0.05).
 The increase in the duration of lactation and deterioration of fertility has associated with an increase in the duration of the service period, which is quite natural, since animals need more time to invade the genital organs and normalize their functioning and restore normal sexual cycle. The difference in the duration of the lactation period when comparing animals with different fertility in all cases was high-reliable at P ≤ 0.001 (td = 3.38–6.00).
 The effect of cow fertility on the duration of their lactation was ηx = 0.160 (at P ≤ 0.001).
 The main indicator that characterizes the economic efficiency of the industry is the profit received from the cow due to the receipt of the calfs and milk. Taking into account the duration of the service period, which exceeded the optimum terms, in the first days of the experimental groups, indicators of non-compliance of products in the form of calves per 100 cows were determined, which made 18.5%, 14.1% and 11.4% respectively.
 The force of influence on the fertility of cows at the age of their first calving was ηx = 0.507 (at P ≤ 0.001).
 According to the received data, the first-calf cows with a tiredness of 6274 kg of milk showed
 the highest calving output in the herd is for 100 cows (89.6%) and reproductive capacity (0.91). The lowest calf output (82.5%) and reproductive capacity (0.84) was found in cows with a milk yield of 6708 kg for 305 days of lactation.
 As the milk productivity increases, the duration of the service period extends from 123.1 to 158.3 days (r = 0.16 ± 0.07, at P ≤ 0.05), and the index of insemination – from 2.35 to 3,02 (r = 0.17 ± 0.08, at P ≤ 0.05). The relationship was straightforward and reliable.
 It is necessary to focus on improving cow fertility, which is the basis of effective milk production. For the successful management of dairy cattle breeding in the conditions of the "Hliborob" farm, we recommend to select the herds of heifers to be retrieved from animals with satisfactory fertility, since this will be economically beneficial for the farm and physiologically optimal for animals.
 A negative correlation was detected between milk productivity and reproductive capacity - with an increase in the fertility index per unit of hopes for cows, it would increase by 148.5 kg of milk.
 Under existing conditions of feeding and keeping on the farm it is expedient to select for further breeding of animals with a productivity level of 6.5 thousand kg of milk for 305 days of lactation. For a more complete realization of the genetic potential of milk production of cows of Ukrainian Black-and-White milk, it is necessary to improve the conditions of their feeding, maintenance.

PERSPECTIVES FOR DEVELOPMENT OF UKRAINE DAIRY CATTLE BREEDING UNDER THE CONDITIONS OF AN ORGANIC PRODUCTION

PERSPECTIVES FOR DEVELOPMENT OF UKRAINE DAIRY CATTLE BREEDING UNDER THE CONDITIONS OF AN ORGANIC PRODUCTION

Comparison of Methods for Monitoring the Body Condition of Dairy Cows

Dairy cows are known to mobilise body fat to achieve their genetic potential for milk production, which can have a detrimental impact on the health, fertility and survival of the cow. Better monitoring of cows with poor body condition (low or high body fat) will lead to improvements in production efficiencies and less wasted resources when producing milk from dairy cows. The aim of this study was to compare different methods for monitoring the body condition (body fat) of dairy cows. The methods used to measure body condition were: ultrasound scanner, manual observation, and a still digital image of the cow. For comparison, each measure was expressed as a body condition score (BCS) on a scale of extremely thin (1) to very fat (5) in quarter intervals. A total of 209 cows at various stages of lactation were assessed. Lin’s concordance correlation coefficient (CCC) and the root mean square prediction error (RMSPE) were used to compare the accuracy of methods. The average BCS across cows was 2.10 for ultrasound, 2.76 for manual and 2.41 for digital methods. The study found that both manual (r = 0.790) and digital (r = 0.819) approaches for monitoring cow body condition were highly correlated with ultrasound BCS measurements. After adjusting correlation coefficients for prediction bias relative to a 45 line through the origin, the digital BCS had a higher CCC of 0.789 when compared to the ultrasound BCS than the manual BCS with a CCC of 0.592. The digital BCS also had a lower prediction error (RMSPE = 28.3%) when compared with ultrasound BCS than the manual BCS (RMSPE = 42.7%). The prediction error for digital and manual BCS methods were similar for cows with a BCS of 2.5 or more (RMSPE = 20.5% and 19.0% respectively) but digital BCS was more accurate for cows of less than 2.5 BCS (RMSPE = 35.5% and 63.8% respectively). Digital BCS can provide a more accurate assessment of cow body fat than manual BCS observations, with the added benefit of more automated and frequent monitoring potentially improving the welfare and sustainability of high production systems.

Combining genetic and physiological data to identify predictors of lifetime reproductive success and the effect of selection on these predictors on underlying fertility traits

Fertility of the dairy cow relies on complex interactions between genetics, physiology, and management. Mathematical modeling can combine a range of information sources to facilitate informed predictions of cow fertility in scenarios that are difficult to evaluate empirically. We have developed a stochastic model that incorporates genetic and physiological data from more than 70 published reports on a wide range of fertility-related traits in dairy cattle. The model simulates pedigree, random mating, genetically correlated traits (in the form of breeding values for traits such as hours in estrus, estrous cycle length, age at puberty, milk yield, and so on), and interacting environmental variables. This model was used to generate a large simulated data set (200,000 cows replicated 100 times) of herd records within a seasonal dairy production system (based on an average New Zealand system). Using these simulated data, we investigated the genetic component of lifetime reproductive success (LRS), which, in reality, would be impractical to assess empirically. We defined LRS as the total number of times, during her lifetime, a cow calved within the first 42 d of the calving season. Sire estimated breeding values for LRS and other traits were calculated using simulated daughter records. Daughter pregnancy rate in the first lactation (PD_1) was the strongest single predictor of a sire's genetic merit for LRS (R2 = 0.81). A simple predictive model containing PD_1, calving date for the second season and calving rate in the first season provided a good estimate of sire LRS (R2 = 0.97). Daughters from sires with extremely high (n = 99,995 daughters, sire LRS = +0.70) or low (n = 99,635 daughters, sire LRS = -0.73) LRS estimated breeding values were compared over a single generation. Of the 14 underlying component traits of fertility, 12 were divergent between the 2 lines. This suggests that genetic variation in female fertility has a complex and multifactorial genetic basis. When simulated phenotypes were compared, daughters of the high LRS sires (HiFERT) reached puberty 44.5 d younger and calved ∼14 d younger at each parity than daughters from low LRS sires (LoFERT). Despite having a much lower genetic potential for milk production (-400 L/lactation) than LoFERT cows, HiFERT cows produced 33% more milk over their lifetime due to additional lactations before culling. In summary, this simulation model suggests that LRS contributes substantially to cow productivity, and novel selection criteria would facilitate a more accurate prediction at a younger age.

PHENOTYPIC CHARACTERISTICS OF THE GENOFOND OF THE CENTRAL INTERBREED TYPE OF UKRAINIAN RED-AND-WHITE DAIRY CATTLE

PHENOTYPIC CHARACTERISTICS OF THE GENOFOND OF THE CENTRAL INTERBREED TYPE OF UKRAINIAN RED-AND-WHITE DAIRY CATTLE

High milk production decreases cow-calf productivity within a highly available feed resource environment.

The beef cattle industry tends to focus on selecting production traits with the purpose of maximizing cow-calf performance. One such trait is milking ability, which is considered the primary influence on weaning weight of the calf. Therefore, the objective of this study was to determine the effect of actual milk yield on reproductive performance, circulating blood metabolites, and calf performance in beef cows in the Southeastern US. Over a 2 yr period, data were collected from 237, 3- to 9-yr-old Angus-sired beef cows on 3 research stations in Tennessee. On approximately d 58 and 129 postpartum, 24-hr milk production was measured with a modified weigh-suckle-weigh technique using a milking machine. Subsamples of milk were collected for analysis of milk components. Milk yield data were used to retrospectively classify cows on actual milk yield as High ( ≥ 10 kg/d), Mod (8 to 9 kg/d), or Low ( < 8 kg/d). Cow body weight (BW) and body condition score (BCS) were collected weekly at each location through breeding. Calf BW was recorded at birth, mid-weight at d 58, and weaning. At d 58 and 129 of postpartum, milk yields were different (P < 0.001) among the treatment groups. Cow BW during the entire study were not different (P ≥ 0.22) with increasing milk yield. Timed-AI pregnancy rate were the lowest (P = 0.02) in the High milk producing cows with no difference (P > 0.05) between Low and Mod milk cows. In addition, overall pregnancy rate continued to be the lowest (P = 0.04) in High milk producing cows with the greatest pregnancy rate in Mod milk cows. Calf mid-weight at ∼d 58 was increased (P < 0.001) in calves from Mod and High milking cows. However, calf BW at weaning was not different (P = 0.22) among calves from different milk treatment groups. Results from this study suggest that even in management systems that modify the grazing environments with harvested feedstuffs, high milk production decreases reproductive efficiency. In addition, increasing milk production up to d 129 postpartum did not result in increased calf BW at weaning, indicating that the genetic potential for calf BW at weaning could not be improved with increased genetic potential for milk production.

Associations of Leptin and Pituitary-Specific Transcription Factor Genes' Polymorphisms with Reproduction and Production Traits in Dairy Buffalo.

This study aimed to detect the genetic variability in Leptin and Pit-1 genes using polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing also to explore their possible associations with reproductive and productive traits of Egyptian buffaloes. Regarding Leptin gene, three genotypes (AA, AG and GG) were identified with frequency of 0.54, 0.40 and 0.06, respectively, and the genotypes were distributed according to the Hardy-Weinberg equilibrium. Allele A was comparatively higher than G with frequency of 0.74 and 0.26, respectively. For Pit-1 gene, the association could not be performed due to the monomorphism (BB). The results showed that AA genotypes were found to be superior in most of production and reproduction traits. AA genotypes yielded more milk (2332.34kg, p=0.04) with higher fat% (6.10, p=0.004) and fat yield (155.75kg, p=0.06), reach peak milk production at 42.19days and required 2.19 services for conception in comparison with GG genotypes. Birthweight of animals with AA genotype was lesser than with GG genotype (39.35 and 43.67kg, p=0.02, respectively). The days open is numerically better in AA genotype animals (99.35days), but the difference between the three genotypes was non-significant. The distinct significant associations reported in this study suggested that Leptin is reputable candidate genetic marker, which might be used to enhance animals' genetic potential for milk production in conjunction with reproduction.

Heritability estimates for enteric methane emissions from Holstein cattle measured using noninvasive methods

The objective of this study was to estimate heritability of enteric methane emissions from dairy cattle. Methane (CH4) and CO2 were measured with a portable air-sampler and analyzer unit based on Fourier transform infrared detection. Data were collected on 3,121 Holstein dairy cows from 20 herds using automatic milking systems. Three CH4 phenotypes were acquired: the ratio between CH4 and CO2 in the breath of the cows (CH4_RATIO), the estimated quantified amount of CH4 (in g/d) measured over a week (CH4_GRAMSw), and CH4 intensity, defined as grams of CH4 per liter of milk produced (CH4_MILK). Fat- and protein-corrected milk (FPCM) and live weight data were also derived for the analysis. Data were analyzed using several univariate and bivariate linear animal models. The heritability of CH4_GRAMSw and CH4_MILK was 0.21 with a standard error of 0.06, and the heritability of CH4_RATIO was 0.16 with a standard error of 0.04. The 2 CH4 traits CH4_GRAMSw and CH4_RATIO were genetically highly correlated (rg=0.83) and they were strongly correlated with FPCM, meaning that, in this study, a high genetic potential for milk production will also mean a high genetic potential for CH4 production. The genetic correlation between CH4_MILK and FPCM and live weight showed similar patterns as the other CH4 phenotypes, although the correlations in general were closer to zero. The genetic correlations between the 3 CH4 phenotypes and live weight were low and only just significantly different from zero, meaning there is less indication of a genetic relationship between CH4 emission and live weight of the cow. None of the residual correlations between the ratio of CH4 and CO2, CH4 production in grams per day, FPCM, and live weight were significantly different from zero. The results from this study suggest that CH4 emission is partly under genetic control, that it is possible to decrease CH4 emission from dairy cattle through selection, and that selection for higher milk yield will lead to higher genetic merit for CH4 emission/cow per day.

Impact of calf nutrition on overall production and productive life of cattle and buffaloes.

Abstract Poor feeding during pre-natal, neonatal and post-natal stages of calves leads to higher age at first calving and overall loss of productive life. Supplying calves an optimal nutrition right from the prenatal stage is vital for their growth and development, and it also allows calves to express their full genetic potential for milk production and reproductive efficiency during the entire lifespan. Maternal nutrition during the last trimester is considered important to genetic programming in utero . The influence of maternal nutrition also reaches the neonatal calf through hormones, growth factors and immune-stimulants incorporated into colostrum, milk and milk replacers. The key is to accelerate the rate of maturation of the calf's ruminal papillae (rumen wall) through the provision of calf starter and grower feeds and good-quality roughages, which favour the digestion of larger proportions of fodder at an early age. Feeding and management practices to promote these processes in crossbred calves are well established; however, in most of the developing nations little is known about these processes in buffalo calves and indigenous ( Bos indicus ) cow calves. Feeding buffalo calves and indigenous cow calves on scientific lines, and rearing them using improved management practices to assist the animals reach puberty sooner, are central factors for improving their productivity and productive life in tropical and sub-tropical regions. By 2050, people living in these regions are estimated to consume about 70% of the additional milk produced.