High-yielding Herds Research Articles

Productivity characteristics of Montbeliard breed cows in the conditions of Uzbekistan

In recent years, Montbeliard cattle have been imported to France from Uzbekistan in order to strengthen the breeding base of cattle and create high-yielding herds and increase livestock production. However, the productivity characteristics of cattle of this breed have not been studied in our hot climate conditions in special studies depending on various factors. Studies have shown that the level of milk yield of co-breeding Montbeliard cows imported to Uzbekistan depends on the type of production. It was found that the milk yield of lactating cows is 672.5 and 958.5 kg higher than that of dairy and meat-milk cows, respectively, and the level of feed coverage is higher than that of dairy products. It is based on the fact that the milk yield of cows also depends on the biomass index and service life. It was found that cows with a biomass of 531-550 kg, typical of the milk type, produced high milk yields. The level of milk productivity of cows is inextricably linked to the service life. Dairy cows with a service life of 81-90 days are characterized by high milk content, milk fat consumption and 4% milk yield. The selection of cows for the optimal service life is an important factor in the creation of productive dairy herds.

The dependence of milk yield on the living weight of cows of Simmental breed

Studies have found that increasing the salinity of dairy cows with Simmental breeds in the herd is important in increasing milk production and creating high-yielding herds. The amount of milk of the cows having 531-560 kg live weight with the type of milk production was 768-1153 kg (P>0,999), milk fat output was 21.6-27.9 kg, 4% milk volume was 540,3-697.1 kg) higher than the different living weight Equinox with the type of milk-meat, and these indicators were determined as 932.5-1401.3 kg), 26.9-38.5 kg.

DEVELOPMENT OF GENETIC RESOURCES OF DAIRY CATTLE BREEDING IN UKRAINE

DEVELOPMENT OF GENETIC RESOURCES OF DAIRY CATTLE BREEDING IN UKRAINE

SELECTION OF RED MOTLEY HOLSTEIN BULLS BY GENOTYPE AND THEIR EXTENSIVE USE IN BREEDING

The article describes the selection of red motley Holstein bulls by genotype imported from Germany to the state enterprise "Uznaslchilik" and their use in breeding practices, which are also characterized by breeding and productivity qualities typical of black motley types. In the study of world breeding practices, new high-yielding herds are being formed by crossing dairy red breeds with red motley Holstein breed bull-improvers. The red motley Holstein breed is also recognized in our country as an improver and is being used in artificial insemination. KEYWORDS: Red motley Holstein breed, breeding and productivity, artificial insemination, crossbreeding, selection and pairing, fertile, individual, genotype, breeding, total merit index, farm useful traits.

Signs of reproductive qualities of sows of different types of adaptation, their variability and correlation

The results of studies of life expectancy and breeding use, as well as the main indicators of reproductive qualities of sows of large white breed of different types of adaptation, the economic efficiency of the research results and the level of correlation between traits are calculated cost-effectiveness of research results and the level of correlation between traits. The research was conducted in the conditions of agro-formations of Dnipropetrovsk region (LTD “Agro-Elita”, SLTD “Druzhba-Kaznacheevka”). The object of the study was sows of large white breed. Evaluation of sows of experimental groups (I – superadaptive, II – mediumadaptive, III – minusadaptive type of adaptation) according to the indicators of the level of adaptation and the main indicators of reproductive qualities were carried out taking into account the successor of quantitative traits: life expectancy, months, duration of breeding use, months, farrowing received, piglets total, head; live pigs obtained, naked; multiplicity, head; weight of the nest at the time of weaning at the age of 28–35 days, kg; duration of intergrowth, days. The adaptation level index and the coefficient of productivity were calculated according to the method of Smirnov V. S. (2003) and Long T. E., Short T. H., Bates R. O (2003) respectively. The economic efficiency of the research results was calculated by according to the indicator “mass of the nest at the time of weaning at the age of 28–35 days, kg”. Analysis of the research results shows that sows of superadaptive type will outperform peers of the opposite class (minusadaptive type) in terms of adaptation level and reproductive capacity by 58.36 and 43.63 % respectively. The proportion of indicator “duration of breeding use, months” to the indicator “life expectancy, months” in animals of superadaptive type is 81.8 ± 0.76 %, minusadaptive – 54.1 ± 2.67 % (lim = 27.7 %; td = 10.00; P < 0.001). An integrated assessment of sow reproductive performance by the performance factor confirms the superiority of sows of the superadaptive type to this group of animal traits of other adaptation types. The paired correlation coefficients between adaptation level indices and reproductive traits in sows of different types of adaptation range from -0.815 (tr = 6.45; adaptation level index × obtained farrowing) to +0.995 (tr = 45.05; life expectancy × duration of tribal use). In order to accelerate the breeding process and create a high-yielding herd of pigs, we suggest that the leading group of sows select animals with an index of “adaptation level” of 6.55–8.90 points.

Тенденції приготування кормосумішей для корів в умовах тваринницької ферми господарства

Further development of agricultural production, in particular, livestock industry requires not only an increase in volume, but also a decrease in the cost of production to increase its competitiveness. The main conditions for ensuring this, along with the availability of high-yielding herds, is to strengthen the forage base and full feeding of animals. Therefore, it is necessary to make extensive use of modern advances in the technology of production and preparation of feed and feeding animals, taking into account the physiological features of digestion depending on their biological species and age. Particular importance of this approach comes when feeding high-yielding animals. They need balanced rations with a high level of energy concentration and a special well-defined feeding regime. Complete balanced nutrition, which can increase the level of absorption of nutrients feed intake and reduce the cost of feed per unit of manufactured products, realized through the preparation of complete feed the mixed. Technological schemes for the preparation of feed mixes for cattle, designed to use fodder components of own production and purchased supplements. The analysis of work of equipment in technological lines and a list of operations and the sequence of their implementation.

USEFUL FEATURES OF DAIRY COWS AND THEIR CONNECTION WITH PRODUCTIVE LONGEVITY

A fundamental genetic improvement of domestic dairy breeds is carried out by using the gene pool of the best foreign breeds, in particular Holstein. This approach has greatly improved the milk productivity of cows, but has led to a significant deterioration in reproduction, longevity, product quality, general animal health etc. Taking into account that the increase of the milk productivity of cows leads to a shortening of their use, this problem will only become aggravated over time. Therefore, it is now necessary to direct scientific research into a comprehensive assessment of animals taking into account the signs of lifelong productivity. In view of the above, the purpose of our research was to study the economic utility signs of dairy cows and their relationship with productive longevity. The research was conducted on cows of Holstein (n = 2902), Ukrainian Black- (n = 14876) and Red-and-White (n = 2176) dairy breeds. To characterize the economic useful signs of animals of the studied breeds based on the materials of the primary zootechnical and breeding records, weighed growth of animals, reproductive capacity, milk productivity and duration and efficiency of lifetime use were studied. It was established that heifers of investigated dairy breeds were characterized by a moderate intensity of growth of live weight, as evidenced by average daily increments from birth to 18 months of age: in animals of Holstein breed – 644, Ukrainian Black-and-White milk breed – 641 and Ukrainian Red-and-White dairy breed 692 g. The first fruitful insemination of heifers of the Holstein breed occurred on average at the age of 19.1, Ukrainian Black and Red-and-White dairy breeds - 20.4 and 20.8 months, while their live weight at that was 405.3; 414.3 and 438.5 kg respectively. The milk yield of the Holstein breed cows, depending on the lactation, was 4846–7920 kg, the fat content in milk was 3.63–3.74% and the amount of milk fat was 181.2–279.7 kg, the Ukrainian Black-and-White milk breed was 4008–6317 kg, 3.63–3.70% and 148.6–228.8 kg respectively, while Ukrainian Red-and-White milk is 4578–6592 kg, 3.74–3.87% and 177.2–245.9 kg. The cows of the given breeds were used in herds only 2.32–2.50 lactation. The highest life milk yield was noted in animals of the Holstein breed (18,669 kg), and the lowest (14,940 kg) in the cows of the Ukrainian Red-and-White breed. Correlation analysis of economic characteristics of dairy cows with indicators of their productive longevity confirms the possibility of conducting an indirect predictive selection of animals in order to form high-yielding herds with long-term economic use. Among the studied features, the greatest predictive value (P < 0.001) for the indicators of life expectancy, productive use, lactation, the number of lactation per life, life yield and lifetime of milk fat have yield of cows for the first (r = -0.217 – +0.205) and the best lactation (r = +0.061 – +0.609). An intermediary predictive selection of animals can also be carried out according to the duration of their first service period (r = -0.462 – +0.106) and live weight during growing season (r = -0.286 – +0.126). It was established that live weight at the first insemination and the first calving significantly influenced the indicators of life yields, economic use and lactation of animals, as evidenced mainly by higher and reliable values of correlation coefficients between these indices. It should also be noted that the correlation coefficients between the live weight of cows in the first calving and the duration of life, productive use, lactation and the number of lactations in life were somewhat higher but negative values (r = -0,130 – -0,070), compared with the between live weight at the time of first insemination and the above indicators of longevity of animals (r = -0,037 – +0,094). This suggests that the effect of live weight on the first calving of animals on their longevity was somewhat higher than the effect of live weight at the first insemination. Our data show that the selection of cows by the age of the first calving and the duration of the first lactation is not significant, since there is practically no link between these features and the indicators of productive longevity.

EMBRYO YIELD OF COWS-DONORS AND FUNCTIONAL ASYMETRY OF THE OVARIES

In recent years, experiments aimed at studying the structural asymmetry of paired organs have been conducted increasingly in veterinary medicine. The main factor, which prompted this interest, was extensive use of reproductive biotechnology methods to solve the problems of infertility. In experiments on laboratory animals and in clinical medicine, several authors have found that the nature of pathological processes in paired organs had some differences. Parameters of species functional asymmetry at the level of systems and organs are considered in terms of enantiomorphousness as a trait of adaptive evolution. The study of structural features of physiological and pathological processes in paired gonads of cows will increase the efficiency of biotechnological methods of folliculogenesis stimulation and production of more viable eggs. On the other side, it will reduce the cost of expensive drugs and working time due to more efficient pre-selection of animals for producing embryos.
 The aim of the research was to study structure and pattern of functional asymmetry of ovaries of high-producing cows and its influence on the level of quality embryos formation.
 Material and methods of research. The researches were carried out during 2011-2012 at two dairy breeding farms – "Agro-Soyuz" JSC (Dnipropetrovsk region) and "RVD-Agro" PE (Cherkasy region). Two groups of high-producing cows were formed of milking breeding stock, yields of which during the best lactation exceeded the average of the herd by 20-60%
 The animals were tested during the phased comprehensive research on suitability to removing embryos from them and use of the selected cows in the group of regular donors of embryos, in accordance with applicable requirements of embryo transplantation technology for cattle. During the selection and preparation of cows-donors, washing embryos and their morphological evaluation, we simultaneously performed collecting and analysing data on the activity of functional entities of the left and the right ovaries during luteal phase by palpation according to the advanced approaches. The comparison was performed during cows’ induced cycles using injections of synthetic analogues of F2α prostaglandin on standard procedures and after hormonally induced polyovulation in donors using follicle stimulating hormone drugs and on the standard and prolonged procedures.
 Results. Pattern of relationship between functional asymmetry of ovaries of high-producing cows-donors and their level of embryo yield was found. Palpation revealed that at cows with sufficient technology and high embryo yield after hormonally induced superovulation, ratio of the number of corpora luteal of the left ovary to the right had a tendency to approach the universal proportion of 38%:62% which is typical for luteogenes of cows in the induced and spontaneous cycles. In group of cows with low yields of high-quality embryos, the ratio of ovarian corpora luteal L: R was significantly different. The observed indicator of functional ovarian asymmetry needs to be researched more and it can be used as a criterion for resource-raising effect at selection of stable donors of embryos at high-yielding herds in the future. The significant change of functional asymmetry of donors-cows’ ovaries after hormone stimulation of polyovulation was shown, including the found phenomenon of inversion of dominant activity of gonads. It was experimentally stated that the high level of producing qualitative embryos for transplantation (9,50-9,86 per washing) was characterized for the cows with sufficient functional asymmetry of ovaries after polyovulation.
 Conclusions. Based on the fact that high-quality embryos from high-producing cows of different breeds will have breeding, biological and economic values in the world market of genetic resources in the next years, it is necessary to step up scientific research to study the patterns of functional asymmetry of the cows’ reproductive system as one of important biological factors influencing on effectiveness of embryo transplantation technology.

EVALUATION OF DAIRY PRODUCTIVITY AND REPRODUCTIVE ABILITY OF UKRAINIAN BLACK-AND-WITE AND RED-AND-WITE MILK COWS DEPENDING ON THE SELECTIONAL DIRECTION OF HOLSTEIN BREED

Formation of high-yielding herds is a rather long breeding process (at least 10–12 years), during which animals of the 3rd–4th generation appear. During this period, it is necessary to preserve a certain scientifically justified direction of selection to perform the tasks, the embodiment of which in life is possible only in the presence of a long-term plan of breeding work. Selection of cows for milk productivity primarily depends on the degree of influence on this feature of the main genetic and environmental factors, taking into account that you can significantly improve the desired attributes.
 The purpose of our research was to assess productive and reproductive animal characteristics of Ukrainian red- and black-and-white dairy breeds, search of the most effective breeding methods for improving the reproductive function of cows and heifers.
 Indicators of economically useful signs of the animals under investigation are calculated according to the data of the primary zootechnical account according to the generally accepted methods of biometric analysis. In the course of the work the genealogical, population, genetic and mathematical methods of studying patterns of inheritance, variability, repeatability, estimation of the genotype of animals and other classical methods of research were used.
 According to the results of our research, it is evident that the best milk production is characterized by the animals obtained by using the Holstein breed of North American breeds. A well-defined difference of 234 kg is observed in the cows of the Ukrainian black-and-white milk breed, and in the red- and-white peers there is an insignificant difference between the groups. That indicates that the high-level animals of the Holstein breed do not fully realize their genetic potential by productivity. It should be noted that the bloodiness of the North American selection of Holstein breeds in the genotypes of both breeds, in contrast to the diet, had a negative effect on the protein content of milk (milk protein content decreased by 0.5–0.9%
 In comparison with the animals of the desirable type of daughter from the European bulls of the Holstein breed in the group of Ukrainian black- and red- and-white dairy breeds were significantly superior to or were at the level of the animals of the desired type for fatty milk and milk protein content, unlike the daughters from the bulls of the North American breeding direction.
 Animals derived from the bulls of the North American breeding Holstein breed had the longest service period 166.1 days, which is 36.4 days more than that of the animals of the same breed, but from the bulls of European breeding Holstein breed (P > 0,05). It was also characterized by a longer give birth period, which amounted to 445.4 days, prevailing at the same time of first-born cows with European genetics of Holstein breed for 36 days (P > 0,05).
 According to the indicator of reproductive ability of animals of Ukrainian black-and-white milk breeds holsteinized by the European type of breeding Holstein breed have a better result of 0.89 in contrast to the peers holsteinized by the North American type of selection 0,86 (P > 0,05). In the comparative analysis of the correlation of reproductive ability of cows with different genotypic groups of both breeds, the cows with the European type of selection of the Holstein breed are preferable to the parameters of the animals of the desired type.
 Conclusions. According to the results of the evaluation of milk productivity, the preference is given to the animals obtained from the bulls of the Holstein breed of North American breeding by quantitative indices but this genetics negatively affected the protein content of milk. Compared to the animals of the desired type, – then both breeding directions are considerably inferior to the parameters of the animals of the desired type, but on qualitative indicators of milk productivity the cows from the bulls of European breeding Holstein breed prevail and their peers with the North American selection of Holstein breed and animals of the desired type.
 According to the performance of the reproductive ability of the daughter of the North American bulls Holstein breed had the longest service- and between the give birth period, and shorter dry period. According to the indicator of reproductive ability, dominated cows by the European type of breeding Holstein breed.

Can UK livestock production be configured to maintain production while meeting targets to reduce emissions of greenhouse gases and ammonia?

Abstract We used a Life Cycle Assessment approach to determine whether the inherent differences in emissions to air among existing livestock production systems could be used to reconfigure the UK livestock sector in order to meet current greenhouse gas (GHG) and ammonia (NH 3 ) targets while maintaining production at current levels. Output, defined as financial value, was optimized across all sub-sectors. Using current management systems the greatest livestock output that could be maintained, while meeting emission reduction targets, was 84% of current. Adopting the most appropriate manure management practices and improved feed conversion ratio enables a further increase in outputs to 86% of current. Dairy production could be maintained at 84.1% of current if all production arises from high-yielding herds with autumn calving, all dairy cow manure is managed as slurry and diets to reduce rumen fermentation are adopted. Increasing the proportion of calves obtained from the dairy herd by 10% could maintain beef production at 85% of current. Raising finishing pigs on slurry systems, raising sows and weaners outdoors, finishing pigs at either 89 or 99 kg and improving dietary nitrogen use efficiency could maintain pig production at 87.5% of current. Manure drying within poultry buildings, immediate incorporation of poultry manures to tillage land and reduced protein feeds would allow 82.2% of current poultry meat production. Eliminating free-range egg systems and drying manure within the building could maintain egg production at 85.5% of current. Replacing lowland sheep herds (other than organic) with upland production could maintain sheep output at 86.4% of current.

Economics of fertility in high-yielding dairy cows on confined TMR systems

The objective of this review paper was to summarise the latest findings in dairy cattle reproductive economics with an emphasis on high yielding, confined total mixed ration systems. The economic gain increases as the reproductive efficiency improves. These increments follow the law of diminishing returns, but are still positive even at high reproductive performance. Reproductive improvement results in higher milk productivity and, therefore, higher milk income over feed cost, more calf sales and lower culling and breeding expenses. Most high-yielding herds in the United States use a combination of timed artificial insemination (TAI) and oestrous detection (OD) reproductive programme. The ratio of achievable pregnancies between OD and TAI determines the economic value difference between both and their combinations. Nonetheless, complex interactions between reproductive programme, herd relative milk yield, and type of reproductive programme are reported. For example, higher herd relative milk yield would favour programme relying more on TAI. In addition, improved reproductive efficiency produces extra replacements. The availability of additional replacements could allow more aggressive culling policies (e.g. less services for non-pregnant cows) to balance on-farm supply and demand of replacements. Balancing heifer replacement availability in an efficient reproductive programme brings additional economic benefits. New technologies such as the use of earlier chemical tests for pregnancy diagnosis could be economically effective depending on the goals and characteristics of the farm. Opportunities for individual cow reproductive management within defined reproductive programme exist. These decisions would be based on economic metrics derived from the value of a cow such as the value of a new pregnancy, the cost of a pregnancy loss, or the cost of an extra day open.

Factors influencing heifer survival and fertility on commercial dairy farms

The average dairy cow survives only three lactations, reducing the availability of replacement heifers. Prenatal losses occur due to early embryonic mortality (about 40%), later embryo loss (up to 20% in high-yielding herds) or abortion (about 5%). A recent survey of 19 UK herds showed that 7.9% of calves were born dead and 3.4% died within 1 month. During the rearing phase, 6.7% of animals were lost before reaching first service at 15 months due to disease or accident and another 2.3% failed to conceive. Many potential replacements therefore never enter the milking herd. This severely limits opportunities for on-farm selection of breeding cows in addition to presenting a welfare issue and causing economic loss. The most profitable animals once lactation is reached combine good milk production with a regular calving pattern. Some aspects of performance are related to age at first calving (AFC), which in turn is influenced by heifer growth rates. Poorly growing animals required more services to conceive, calved later and subsequently performed badly. Optimum fertility and maximum yield in the first lactation were associated with an AFC of 24 to 25 months. However, heifers calving at 22 to 23 months performed best in terms of total milk yield and survival over the first 5 years, partly because good heifer fertility was associated with better fertility later. We have investigated some possible juvenile predictors of future performance. Low-birth-weight calves were more likely to come from either primiparous mothers or older dams (3+ lactations) with higher peak milk yields, suggesting that the uterine environment may limit prenatal calf growth due to competition for nutrients with maternal growth or milk production. Linear trait classification scores for frame size show genetic correlations with longevity. The skeletal measures of height and crown rump length in 1-month-old calves was correlated to subsequent stature, and frame size was correlated to weight at 15 months. It may thus be possible to predict performance from simple size measurements as juveniles. Neither endogenous nor stimulated growth hormone (GH) release in 6-month-old calves were related to milk yield in the first three lactations, but size of a stimulated GH peak was positively related to milk energy values in the first lactation. Cows with delayed ovulation (>45 days) in the first lactation had a higher GH pulse amplitude and lower IGF-I as a juvenile. Cows that partition excess energy into milk in their first lactation may suffer reduced longevity.

Associations Between Herd Characteristics and Reproductive Efficiency in Dairy Herds

Dairy herds worldwide are experiencing a decline in reproductive efficiency at the same time as management methods are changing. This study aimed to investigate the extent to which herd-level characteristics were associated with reproductive performance. Data from herds using artificial insemination (AI) in the Swedish Official Milk Recording Scheme that had more than 45 cows were included in the study (total of 2,728 herds). Reproductive performance was measured as the average for each herd for the calving interval, calving to first AI interval, calving to last AI interval, number of AI per animal submitted for AI, and culling attributed to reproductive problems. Herds with mainly Swedish Holstein cows had longer calving intervals, calving to first AI, and calving to last AI compared with herds with mainly Swedish Red and White cows. Large herds had shorter calving to first AI but a greater number of AI than small herds, whereas small herds had greater culling attributed to reproductive problems than large herds. Low-yielding herds had longer calving intervals, calving to first AI, and calving to last AI and had greater culling attributed to reproductive problems than high-yielding herds, whereas herds with high milk yields had a greater number of AI than low-yielding herds. Herds with automatic milking systems had shorter calving intervals, calving to first AI, and calving to last AI and had lesser odds for culling attributed to reproductive problems when compared with herds with ordinary pipeline milking systems. Herds that used Advanced Feed Advisory Services had shorter calving to first AI but a greater number of AI and greater culling attributed to reproductive problems. Herds using TMR had longer calving intervals and calving to last AI than herds that did not. Herds with tie stalls had longer calving intervals, calving to first AI, and calving to last AI, and organic herds had shorter calving intervals, calving to first AI, and calving to last AI compared with conventional herds. We found that herds with do-it-yourself inseminations had longer calving intervals and calving to first AI. Our study showed numerous associations between herd characteristics and reproductive performance. When allocating advisory service resources to improve reproductive performance, the focus should be on herd characteristics that are easy to influence, such as TMR and do-it-yourself inseminations.

北海道根室管内の217乳牛群における死廃・病傷事故と乳量水準および飼養形態との関連

Effects of milk yield and feeding system on death and disease incidence and average calving numbers were examined in 217 dairy herds in the Nemuro district of Hokkaido. High-yielding herds tended to demonstrate a lower calving rate, higher culling rates, lower milk somatic-cell counts, and fewer non-pregnant days. There was little difference in death and disease incidence related to milk yield and feeding systems. Disease rateswere higher in high-yielding herds. Disease rates were higher among cattle kept tied in barn stalls than in those free in their stalls. Incidences of mastitis, displaced abomasum, gastroenteric disorder, and ketosis were higher in high-yielding herds. Incidences of mastitis, teat injury, and ovarian disorder were higher in herds tied in barn stalls, whereas occurrences of displaced abomasum and milk fever were more numerous in herds housed free in barn stalls. These results indicate a close association between disease prevalence and feedingsystem management.

Relationships between sires' transmitting ability for production and daughters' production, food intake and efficiency in a high-yielding dairy herd

ABSTRACTMilk production and food intake records were available on individual animals from a high-yielding Holstein-Friesian herd in which selection had been practised on fat plus protein yield using nationally available artificial insemination sires. The relationship between sires and maternal grandsires' transmitting ability (ICC), expressed as a pedigree index (sire ICC + 0·5 maternal grandsire ICC), and offspring performance for milk production traits, food intake, and gross efficiency (milk energy (MJ)/total energy intake (MJ)) was investigated. The data comprised 475 26-week (data set 1) and 293 38-week (data set 2, a subset of 1) records, and for each data set analyses were conducted on heifers, cows and pooled lactations. Regressions of fat plus protein yield, fat yield, protein yield, and milk yield on their corresponding pedigree index were not far from the theoretical expectation (for a full lactation) of 1, for heifers (0·71 (s.e. 0·20), 0·72 (s.e. 0·20), 0·74 (s.e. 0·21) and 0·75 (s.e. 0·19), respectively), but slightly lower for the pooled lactations (0·57 (s.e. 0·20), 0·55 (s.e. 0·20), 0·67 (s.e. 0·19) and 0·64 (s.e. 0·15)) in data set 1. Regressions of fat plus protein yield, food intake and gross efficiency on pedigree index for fat plus protein yield, each trait expressed as a ratio of herd mean, were 1·31 (s.e. 0·37), 0·38 (s.e. 0·19) and 1·04 (s.e. 0·35) for heifers and 0·89 (s.e. 0·31), 0·48 (s.e. 0·18) and 0·59 (s.e. 0·26) respectively, for pooled lactations, in data set 1. Regressions for cow lactations were lower. Similar results were obtained with data set 2. In this study, a genetic increase of proportionately 0·1 in fat plus protein yield of daughters of sires of high genetic merit for fat plus protein yield, was accompanied by a proportional genetic increase of 0·029 in food intake and a 0·079 proportional genetic increase in efficiency.

Use of fish heal to reduce compound feed usage in high yielding dairy herds

Compound feeds are frequently used at a fixed rate of 0.36kg to 0.40kg/kg milk produced, in addition to forage and other home-grown feeds. Such linear scales take no account of the curvilinear response of milk yield to concentrate feed intake, nor of the substitution effect of concentrate feed upon forage intake. In high-yielding herds, the use of fixed rate scales can result in the provision of concentrate feeds in excess of 10kg/d. An experiment was designed to evaluate whether milk yields could be maintained while reducing concentrate feed intake, and therefore placing greater reliance on forage intake, and including sugar-beet pulp as a source of highly digestible but non-starchy concentrate, and fish meal as a source of high quality undegraded dietary protein

The Appetite Potential of Jersey Cows

A previous trial (Brigstocke et al., 1982) had indicated that mature Jersey cows ate considerably more dry matter (DM) in relation to their body size than was currently projected from the multiple regression equations used for appetite prediction. However this trial was run on one large high-yielding herd with only a small number of animals and it was not known whether the results were applicable to the more average Jersey producer.

DIFFERENCES IN FEEDING AND MANAGEMENT ASSOCIATED WITH MILK YIELDS IN ONTARIO DAIRY HERDS

Data were collected on feeding and management factors in 56 DHI and ROP tie-stall dairy herds in Ontario during three visits to each herd throughout a production year. High herd average milk yield was associated with high average nutrient intake (specifically energy and crude protein). Owners of high-producing herds demonstrated superior feeding and management. High nutrient intake in early lactation was associated with special efforts to increase intake and maintain cow health during the periparturient period. Higher proportions of concentrate were fed postpartum. Dry cows were more often separated from lactating cows and rations were more frequently balanced in response to changes in type and quality of forage fed in high-yielding herds. Longer calving intervals and high percent days in milk contributed directly to lower yield by extending lactations into the downward portion of the lactation curve. Key words: Feeding, management, dairy cattle, Ontario

The effects of lactation, pregnancy and calendar month on milk records

ABSTRACTThe effects of the lactation, pregnancy and calendar month on monthly milk records of 1st and 3rd lactation Israeli-Friesian dairy cows were studied. The analyses involved 717 966 monthly records in 76 788 lactations of cows diagnosed as pregnant in herds providing 20 or above lactations per herd per year and lactation number. The records were grouped into 18 lactation classes according to yield post partum: high, medium and low cows within high, medium and low herds, separately for 1st and 3rd lactations.The objects of the investigation were to estimate factors for relating persistency to peak yield, and to examine how interactions between peak yield and persistency should be taken account of in post partum breeding policies.The major factor affecting yield was the number of months post partum; heifers dropped in yield by 0·173 from the 1st to the 10th month of lactation and cows by 0·46. The herd level affected the shape of the lactation curve. In high-yielding herds peak yields were achieved later than in low-yielding herds, but the rates of yield decline from the 2nd to the 10th month were similar in high- and low-yielding herds. Within herds, there were large differences in the rate of decline between cows with high and low peak yields. The monthly decline within herds from the 2nd to the 10th lactation month for animals of high and low peak yield were –0·0347 and –0·0217 for heifers and –0-0633 and –0·0520 for cows.Effects of pregnancy on milk yields were observed from the 1st month post conception, but the effects were small. The effects of 7 months of pregnancy on test-day yields were 3 to 4 kg milk, independent of the yield level of the cow. It was suggested that the effect of herd level could be disregarded but that account should be taken oflactation number and the yield level of the cow within her herd. Heifers and cows in high-yielding herds may be mated later than cows in low-yielding herds. Since pregnancy had a similar effect on high- and low-producing cows, and within herds the higher yielding cows were less persistent in yields than the remainder, it might be a reasonable management policy to breed most of the cows in a herd of a particular lactation at approximately the same time post partum.

The effects of days-open on milk yield and on breeding policy post partum

ABSTRACTThe effects of days-open on milk yields in current lactations and in following lactations were estimated from 71 911 current and 68 693 following lactation records. Yields were expressed as 305-day, total and annual records, where annual record = 365 × (total yield/days between calvings).The data were grouped according to current days-open, corrected for initial yield differences and analysed separately for heifers and cows in Moshav (moderate-yielding) and Kibbutz (high-yielding) herds. Current 305-day records increased by 15 to 18 kg milk/day-open up to 90 days-open, and 2 to 3 kg/day-open thereafter. In contrast, the effects of increasing days-open on annual yields were generally small and negative, being positive only for heifers up to 90 days-open. Thus 305-day records heavily under-rated annual yields of fertile cows. For current lactations, 70 to 100 days-open for heifers and 30 to 50 days-open for cows resulted in the highest annual production. Yields in following lactations were positively associated with days-open in the previous lactation. The effect was highest in high-yielding herds, suggesting that high-yielding cows respond positively to some rest between calvings.Combining the effects of days-open on current and following lactation yields and on the calf crop: in high-yielding herds heifers had the highest productivity when mated not earlier than 70 days post partum, while in moderately-yielding herds days-open did not affect productivity. Cows in high-yielding herds achieved highest productivity at 41 to 90 days-open, while cows in moderately-yielding herds were most productive when mated as early as possible.A comparison of the economic value of sire fertility and sire transmitting ability for milk production showed that fertility may often be over-rated.