Live Weight Of Cows Research Articles

Assessment of the effect of inbreeding on the productive longevity of dairy cattle

When breeding dairy cattle, both heterogeneous and homogeneous selection is used. Assessment of the influence of the degree of inbreeding on the productive quality and duration of the productive longevity of cows. It was found that despite a slight increase in milk yield in inbred animals (by 93 - 378 kg depending on the degree of inbreeding and by 73 kg on average for the group of inbred animals), a decrease in the qualitative indicators of milk, the mass fraction of fat and the mass fraction of protein and a significant increase in live weight of cows (P≤0.05) obtained using inbreeding. There is a superiority of herd cows over the requirements of the standard for black and white breed by 2500 - 2947 kg in groups (on average by 2624 kg) in milk yield and by 0.31% in the mass fraction of fat in milk; for Holstein breed these results are slightly lower and amount to 1500-1924 kg (an average of 1624 kg) for milk yield. The greatest amount of milk and nutrients was obtained from inbred cows with moderate levels of inbreeding and outbred animals, due to an increase in the duration of productive use. With the age of the cows, their milk production practically does not change, remaining at a fairly high level. The use of closely related crossbreeding with a simultaneous increase in the blood level in the Holstein breed leads to a slight increase in milk yield and the duration of productive longevity by 0.2-0.4 lactation. In lifetime productivity, inbred cows with a moderate degree of inbreeding remain superior. Outbred animals are at second place.

INFLUENCE BLOOD SHARE AND THE LINEAR ACCESSORY ON INDEXES OF DAIRY EFFICIENCY OF COWS

Blood inflow of Holstein breed in Mari El cattle breeding, which began in 80s of the last century, had a positive impact on the dairy productivity of Black-and-White cattle. The research explores the impact of Holstein breed bloodline and lineage on the main indicators of cows’ dairy productivity in OAO Ovoshchevod. The productive age increasing, the live weight of cows in the main herd increased as well while the animals were relatively small. The cows of the eighth and ninth calves had the maximum live weight. On average, the cows with the third complete lactation (6791.5 kg) had the highest milk yield. The mass fraction of fat was on average higher than the basic fraction and was equal to 3.71%. The increase of milk fat concentration was observed in cows of the fifth and sixth lactations, with the offsprings of Black-and-White bull lines being the most fatty. There is a direct correlation between milk yield and the degree of blood flow in the Holstein breed. The fattiest milk cows were those with a blood content of 19%, while the cattle with a blood content of 75% had the lowest fat concentration in milk. According to the hospitalization data, most of the cows in the herd (including the first heifer cows) belong to the R. Sawring line. The female offsprings of Adam, Rikus and M. Chiftein bulls differed in the most productive longevity. The most abundant were cows belonging to M. Chiftein line. Female offsprings of Black-and-White bulls were inferior to the Holstein ones in average by 324 kg of milk. This feature was traced from first to fifth lactation. In the lactation section, the most fatty-milk cows of the Rikus and M. Chiftein lines were the fattest. As the share of blood in the Holstein breed increased, the milk yield per cow in the main herd increased as well. Thus, for cows with blood content of 18.75%, the average milk yield for all lactations was 6313 kg of milk. Further blood inflow of Holstein bulls led to this parameter increasing by 4% on average for cows with blood content of 25 and 37.5% for Holstein breed.

ECONOMICALLY USEFUL SIGNS OF DAIRY BREEDS CATTLE IN HERDS OF KIROVOGRAD REGION

ECONOMICALLY USEFUL SIGNS OF DAIRY BREEDS CATTLE IN HERDS OF KIROVOGRAD REGION

Relationship of Longevity with Productive and Reproductive Variables in Nelore Cows of the Bolivian Tropic

The objective of this study was to evaluate the relationship between longevity with productive and reproductive efficiency variables of Nelore cows in grazing systems in the Bolivian tropics. Retrospective data corresponding to the period 1992-2019, belonging to the Cooperativa Agropecuaria Integral San Juan de Yapacaní and the Foundation Technology Center on Agriculture and Livestock, Santa Cruz-Bolivia were used. The data corresponding to 774 Nelore breed cows, primiparous and multiparous discarded with a total of 4050 calvings were evaluated. The following variables were analyzed: Number of calves, live weight of cow in kg, calf weight at birth in kg, calf weight at weaning in kg, total calf weight in kg, age at first calving in months, longevity in days and calving interval in days. Cows born in the year (1985-1995) are those that arrive later to have their first calving, have a greater calving interval, have greater longevity, similar weaning weight, lower birth weight, lower live weight and higher weight total calf. While cows born in the year (2005-2015) are those that arrive younger to have their first calving, they have a shorter calving interval; have shorter longevity, similar weaning weight, higher birth weight, live weight intermediate and lower total calf weight. For the three periods analyzed, the length of life increases between 0.66-0.95 days on average when the age at first calving increases by one unit, between 1.78-2.99 days on average when the calving-calving interval increases by one unit and between 1.77-1.83 days on average when total calf weight increases by one unit. It is concluded that it was possible to find a model that explained that the greater longevity of Nelore cows in a grazing system in the Bolivian tropics was related to the older age at first calving, the greater calving interval and the greater kg of weights total calves.

New breed of dairy cattle Sibiryachka

Based on the use of the best domestic and world gene pool of the Holstein breed, a domestic highly productive breed of cattle with a genetic potential of more than 10 000 kg of milk per lactation adapted to the climatic conditions of Siberia was created. When breeding it, different reproductive crosses were used. As a result, a competitive livestock breed with a population of 26 770 heads was obtained. The productivity of 10 129 cows at the time of breed testing averaged 7,461 kg of milk with a fat content of 3.78% and a protein content of 3.16%. In terms of milk yield and protein content in milk, they surpass Black-and-White cows by 1,460 kg and 0.05%, respectively. However, the animals of the original breed have a higher fat content of milk, by 0.14%. The live weight of cows of Sibiryachka breed is 36 kg (6%) more than that of Black-and-White cows. Young animals of the new breed are intensively growing and developing. At all ages, their live weight is higher than Black-and-White peers. The average daily increase from birth to one year for heifers of the new breed was 770 g, for Black-and-White peers – 700 g. For a growing period of up to 18 months, daily growth averaged 706 and 673 g, respectively. The live weight of heifers at 18 months is 424 kg, Black-and-White – 405 kg, which allows insemination of heifers of Sibiryachka breed 24 days earlier. The average yield of calves over 3 years in the new breed was 82.7%, in the original one it was 3.7% less. The period of use of the cows of the created breed is 3.47 calving, which is 8% more compared to the Black-and-White breed.

Evaluation of production efficiencies at pasture of lactating suckler cows of diverse genetic merit and replacement strategy

Feed costs account for the largest proportion of direct cost within suckler beef production systems. By identifying the cow type with enhanced capability of converting grazed herbage to beef output across lactations, suckler cow systems would become more efficient and sustainable. The objective of this study was to estimate grass DM intake (GDMI) and production efficiency among lactating suckler cows of diverse genetic merit for the national Irish maternal index (Replacement Index) which includes cow efficiency components such as milk yield and feed intake. Data from 131 cows of diverse genetic merit within the Replacement Index, across two different replacement strategies (suckler or dairy sourced), were available over two grazing seasons. Milk yield, GDMI, cow live weight (BW) and body condition score (BCS) were recorded during early, mid and late-lactation, with subsequent measures of production efficiency extrapolated. Genetic merit had no significant effect on any variables investigated, with the exception of low genetic merit (LOW) cows being 22 kg heavier in BW than high genetic merit (HIGH) cows (P < 0.05). Beef cows were 55 kg heavier in BW (P < 0.001), had a 0.31 greater BCS (P < 0.05) and 0.30 Unité Fourragère Lait (UFL) greater energy requirement for maintenance compared to dairy sourced beef × dairy crossbred (BDX) cows (P < 0.001). The BDX had 0.8 kg greater GDMI, produced 1.8 kg more milk (P < 0.001), had a 0.8 UFL greater energy requirement for lactation and produced weanlings that were 17 kg heavier in BW than beef cows (P < 0.05). Subsequent efficiency variables of milk per 100 kg BW (P < 0.001), milk per kg GDMI (P < 0.001) and GDMI per 100 kg BW (P < 0.001) were more favourable for BDX. The correlations examined showed GDMI had moderate positive correlations (P < 0.001) with intake per 100 kg BW, net energy intake per kg milk yield, RFI and intake per 100 kg calf weaning weight but was weakly negatively correlated to milk yield per kg GDMI (P < 0.001). No difference was observed across genetic merit for beef cows for any of the traits investigated. Results from the current study showed that, while contrasting replacement strategies had an effect on GDMI and production efficiency, no main effect was observed on cows diverse in genetic merit for Replacement Index. Nonetheless, utilising genetic indexes in the suckler herd is an important resource for selecting breeding females for the national herd and phenotypic performance generated from this study can be included in future genetic evaluations to improve reliability of genetic values.

Characteristics of half-siblings cows’ by growth and milk productivity

It is proved that the live weight of replacement heifers, the intensity of their formation and milk productivity in primiparous cows depends on father origin, in particular, the value of the index of live weight formation between groups of half-siblings ranges from 68,9 to 82.3 (for comparing ages 6–0 and 12–6 months), from 15,1 to 18,4 (6–3 and 9–6 months), from 23,8 to 28,6 (6–3 and 12–9 months); average daily growth rate in the age of 0–12 months – from 659 to 717 g, 12–18 months – from 500 to 585 g; live weight at the age of 12 months – from 367 to 399 kg; 305-day milk yield – from 5295 to 7595 kg, fat content in milk – from 3,70 to 3,78 %, protein content – from 3,23 to 3,34 %, milk fat – from 197 to 286 kg, milk protein – from 175 to 253 kg. Regardless of the method of determining the index of live weight formation, the higher values of them had daughters of sires M. Nirvana 101709244 (82,3; 18,3; 26,9, respectively), B. Buick 10789585 (80,0; 18,1; 28,6) and M. W. Tahoe 8189401 (80,1; 18,4; 27,7). There were determined differences (P &lt; 0,001) between half-siblings by the average daily growth at the age 0-12 and 12-18 months. At the age of 0-12 months, the higher average daily growths showed daughters of sires M. W. Tahoe 8189401, Flame 112302008 and B. Buick 10789585 (on average 711 g), aged 12–18 months – daughters of sires M. Nirvana 101709244, N. Alfons 353588796, H. R. Artist 6284191 and H. Hadley 123055802 (on average 566 g). The higher intensity of growth of replacement heifers up to 12 months was not related to higher milk productivity in primiparous cows. The advantage of milk yield (+606…+1373 kg, P &lt; 0,001), milk fat (+25…+54 kg, P &lt; 0,001) and milk protein (+22…+48 kg, P &lt; 0,001) was observed in daughters of sires M. Estimate 5925716 and N. Alfons 353588796, whose live weight at the age of 18 months did not exceed the average in the group. The low milk productivity (–525…–927 kg of milk compared to the average, –18…–44 kg of milk fat and –8…–30 kg of milk protein) were characterized for daughters of bulls Flame 112302008 and M. W. Tahoe 8189401, which had significantly higher intensity of growth and live weight formation. Based on the variance analysis it was established that the effect of parentage on the live weight of cows from birth to 18 months was 24,4–43,6 % of the total phenotypic variation, the average daily growth rate – 27,5–47,7 %, traits of milk productivity – 18,0–30,1 % with a high probability (P &lt; 0,001) Key words: dairy cattle, parentage, half-siblings, the index of live weight formation, milk productivity, power of influence.

PSXI-41 Investigating the relationship between life history factors, live animal auction price, and carcass quality of cull dairy cows

Abstract High production efficiency is crucial for the competitiveness and sustainability of the dairy industry. To maintain high production, maximize profitability, and allow an accelerated genetic improvement, it is recommended that between 25–30% of dairy herds be renewed each year. Cull dairy cows contribute for approximately 10% of the total beef produced in the United States, being significantly important as a beef source for the meat industry. Furthermore, cull cows provide an important additional income to dairy farmers. However, culling decisions should be carefully made, taking into consideration herd replacement rate, cow performance, milk and beef prices, and the potential price that each cow might be paid for. The objective of this study was to investigate the relationships between life history factors, live animal auction price, and carcass quality of cull dairy cows. Data from three Wisconsin herds were collected using DairyComp software, from January 2018 to January 2019. Hundredweight (cwt) prices paid for each cow (n = 84) were obtained from a marketing auction, and their carcass traits were provided by a commercial meat packing plant. Correlation and multiple linear regression analyses were used to investigate the dependencies between variables. Results indicate that lactation number and days in milk significantly affect cow live weight and that these three variables together with season of the year and farm provide a good predictor of cwt price (adj R2 = 71.7%). Moreover, there were also significant and moderately strong correlations between cwt price and some carcass quality indicators such as dressing (r = 0.57, P &amp;lt; 0.001), trimming losses (r = -0.25, P &amp;lt; 0.05), and grade (r = -0.58, P &amp;lt; 0.001). In conclusion, cull cow cwt price and carcass quality can be improved by taking into account cows life history factors when making culling decisions.

Influence of various selection options on economic and useful signs of the red-and-white cattle

It has been established that the spontaneous use of closely related mating in utility herds in most cases does not give the desired results. The use of close and close inbreeding leads to a decrease in milk yield, live weight of cows and prolongs the service period. When breeding record-keeping cows, moderate and distant inbreeding makes it possible to get along with crosses of large, highly productive lines, distinguished by good health and good reproductive abilities of animals. The degree of heritability of breeding traits with homogeneous selection turned out to be higher than with heterogeneous selection. An increase in the degree of heritability with homogeneous selection can be explained by a clearer manifestation of the additive effect of genetic factors.

Longevity of Nelore Cows of the Bolivian Tropics. Is It Possible to Explain It Through Productive Variables?

The objective of this work was to evaluate the longevity and its relationship with productive variables of Nelore cows in grazing systems of the Bolivian tropics. Retrospective data were used corresponding to 259 Nelore breed cows, primiparous and multiparous discarded with a total of 800 births, in the period between 2005 and 2019, belonging to the Cooperativa Agropecuaria Integral San Juan de Yapacan&amp;iacute; (CAISY) located in the San Juan Japanese Communities, Santa Cruz, Bolivia. The variables analyzed were: Live weight of cow (WC) in kg, Weight of the calf at birth (WCB) in kg, Weight of calf at weaning (WCW) in kg, Total weight of weaned calf (WWC) in kg, Age at first calving (AFC) in months, Number of calvings (NC), Longevity (L) in days, Calf Index (CI) in kg, Accumulated Productivity (PAC) in kg, Total calf production (CP) in kg, Efficiency of Stock (ES) in kg. In order to respond to the main objective of this work, the relationship between the life longevity of the cow and the other productive variables was studied. For this, first principal component analysis (PCA) was carried out, by means of which the space dimension of the productive variables was reduced creating new linearly independent variables and in this way avoid problems of multicollinearity in the model, because the productive variables in some cases turned out to be correlated. Then, the first three main components that explain 77% of the total variability of the data were retained and interpreted as follows: The PC1 was high and directly correlated with the variables NC, Kg produced total, % of stock efficiency, PAC and Kg produced meat / day, therefore can be thought of as an indicator of &amp;quot;productive efficiency&amp;quot;. PC2 was an indicator of &amp;quot;efficiency in rebreeding&amp;quot; since it presented altar and direct correlations with WC and AFC. PC3 was high and directly correlated with birth weight and weaning weight, which is interpreted as an indicator of &amp;quot;breeding efficiency&amp;quot;. Finally, a multiple linear regression model was adjusted considering Longevity as a function of productive efficiency, breeding efficiency and rebreeding efficiency (p-value &amp;lt;0.0001 in the three cases). 87% of the total variability of L (days) is explained by the model. It is concluded that Longevity is related to productive indicators for this group of Nelore cows in grazing systems of the Bolivian tropics.

ECONOMICALLY USEFUL SIGNS OF DAIRY BREEDS CATTLE IN HERDS OF RESEARCH FARMS OF THE NETWORK OF THE NATIONAL ACADEMY OF AGRICULTURAL SCIENCES OF UKRAINE

ECONOMICALLY USEFUL SIGNS OF DAIRY BREEDS CATTLE IN HERDS OF RESEARCH FARMS OF THE NETWORK OF THE NATIONAL ACADEMY OF AGRICULTURAL SCIENCES OF UKRAINE

Effect of late prepartum fibre-based diets on the live weight changes and reproduction of Holstein cows in the subsequent lactation period

The objective of this study was to evaluate two late prepartum fibre-based diets that differed in non-structural carbohydrate (NFC) and protein levels on live weight (LW) changes and fertility traits of Holstein cows until 120 days postpartum. At 30 days before calving, 120 pregnant Holsteins (heifers, n = 54 and dry cows, n = 66) from the Elsenburg herd were assigned to two nutritional treatments according to parity, expected calving date, LW, and milk production during the previous lactation. Prepartum heifers and cows were fed independently a similar type and level of a prepartum concentrate, associated with an ad libitum intake of either unchopped oat hay for the control group or a partial total mixed ration (pTMR: oat hay (48%), lucerne hay (43%) and soybean oil cake meal (9%)) for the treatment group. After parturition, cows in both the control and treatment groups were maintained on ad libitum cultivated irrigated kikuyu-ryegrass pastures, supplemented each with a post-partum concentrate of 7 kg/day from calving until 120 days in milk (DIM). As expected, young and still growing primiparous cows were significantly lighter in pre- and post-partum LW traits compared with mature multiparous cows (parity &gt; 3). Prepartum LW of cows was similar between the control and the treatment in both parity groups. Post-partum LW of the primiparous cows differed significantly between the control and the treatment, which were 488 ± 9 and 507 ± 13 kg, respectively. However, no difference was observed in terms of post-partum LW of multiparous cows of the control and the treatment groups, which were 579 ± 10 and 579 ± 8 kg, respectively. Primiparous cows that received the prepartum oat hay-based diet showed significant decrease in post-partum LW loss changes, LWnadir, LW loss at nadir and rate of LW loss from calving to LWnadir in comparison with their counterparts on the prepartum pTMR-based diet, but these LW traits were similar in multiparous cows. Prepartum diets did not have an effect on post-partum fertility parameters of the multiparous cows, whereas primiparous cows that received the control diet recorded a significantly longer interval from calving to first service (CFS) in the subsequent lactation in comparison with their counterparts fed the treatment diet i.e. 117 ± 9 and 86 ± 8 days, respectively. Proportions of cows that were pregnant at 120 DIM were similar in the subsequent lactation between groups that received the prepartum oat hay- and pTMR-based diets in both parity groups. Further research is required to investigate different prepartum feeding periods and nutritional approaches involving various levels and sources of energy and protein nutrients to encourage post-partum metabolic and hormonal responses that benefit the fertility of dairy cows in the subsequent lactation.Keywords: Dairy, dry period, non-structural carbohydrate, protein, postpartum, pregnancy

Economic selection index in small rural dairy farms.

This study aimed to calculate economic values (EVs) and economic selection indices for milk production systems in small rural properties. The traits 305-d milk yield in kg (MY), fat (FP) and protein (PP) percentage, daily fat (FY) and protein (PY) yield, cow live weight in kg (LW), calving interval (CI), and logarithm of daily somatic cell count (SCC) in milk were considered the goals and selection criteria. The production systems were identified from 29 commercial properties based on the inventory of revenues and costs and of zootechnical field data. Later, bioeconomic models were developed to calculate the productive performance, revenues, and costs concerning milk production to estimate EVs, which were calculated as the difference in annual profit with dairy production resulting from a change in one unit of the trait while keeping the others constant and dividing the value by the number of cows. After the EVs were known, ten economic selection indices were estimated for each system so they could be compared by modifying the selection criteria and calculating the relative importance of each selection criteria, the accuracy of the economic selection index, and response expected to the selection in USD, among other parameters. One of the systems detected was called less intensive (LS) and was characterized by having ten cows in lactation that produced 13·5 l/d and consumed 1·8 kg of concentrate/d. The second system detected was called more intensive (IS) and had 22 cows in lactation that produced 17·5 l/d and consumed 3·4 kg of concentrate/d. Monthly profits per cows in lactation of USD 2·60 and USD 68·77 were recorded for LS and IS, respectively. The EVs of the traits MY, FP, and PP were all positive, while for the other traits they were all negative in all situations. The best economic selection indices were those featuring selection criteria MY, LW, and CI, while the trait LW had the greatest importance in both systems. These results indicate that animal frame must be controlled in order to maximize the system's profit.

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 &lt; 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.

Comparative grazing behaviour of lactating suckler cows of contrasting genetic merit and genotype

The objective of this study was to determine if differences in grazing behaviour exist between lactating suckler cows diverse in genetic merit for the national Irish Replacement index and of two contrasting genotypes. Data from 103 cows: 41 high and 62 low genetic merit, 43 beef and 60 beef x dairy (BDX) cows were available over a single grazing season in 2015. Milk yield, grass dry matter intake (GDMI), cow live weight (BW) and body condition score (BCS) were recorded during the experimental period, with subsequent measures of production efficiency extrapolated. Grazing behaviour data were recorded twice in conjunction with aforementioned measures, using Institute of Grassland and Environmental Research headset behaviour recorders. The effect of genotype and cow genetic merit during mid- and late-lactation on grazing behaviour phenotypes, milk yield, BW, BCS and GDMI were estimated using linear mixed models. Genetic merit had no significant effect on any production parameters investigated, with the exception that low genetic merit had a greater BCS than high genetic merit cows. Beef cows were heavier, had a greater BCS but produced less milk per day than BDX. The BDX cows produced more milk per 100 kg BW and per unit intake and had greater GDMI, intake per bite and rate of GDMI per 100 kg BW than beef cows. High genetic merit cows spent longer grazing and took more bites per day but had a lower rate of GDMI than low genetic merit cows, with the same trend found when expressed per unit of BW. High genetic merit cows spent longer grazing than low genetic merit cows when expressed on a per unit intake basis. Absolute rumination measures were similar across cow genotype and genetic merit. When expressed per unit BW, BDX cows spent longer ruminating per day compared to beef. However, on a per unit intake basis, beef cows ruminated longer and had more mastications than BDX. Intake per bite and rate of intake was positively correlated with GDMI per 100 kg BW. The current study implies that despite large differences in grazing behaviour between cows diverse in genetic merit, few differences were apparent in terms of production efficiency variables extrapolated. Conversely, differences in absolute grazing and ruminating behaviour measurements did not exist between beef cows of contrasting genotype. However, efficiency parameters investigated illustrate that BDX will subsequently convert herbage intake more efficiently to milk production.

Enteric methane output from selected herds of beef cattle raised under extensive arid rangelands

Extensively raised beef cattle contribute to the highest levels of enteric methane (CH4) gas emissions among all livestock. Expensive techniques and logistics hinder monitoring of such gas. Therefore, the objective of this study was to use an inexpensive laser methane detector (LMD) apparatus to determine the enteric CH4 levels from a herd of beef cows raised on semi-arid rangelands. A total of 24 cows were selected from Boran and Nguni cows (n = 12 per breed) from two different farms. The parities of the cows were as follows: parity 1 (n = 6), parity 2 (n = 6), parity 3 (n = 6) and parity 4 (n = 6). An observer used a hand-held LMD to measure enteric CH4 emissions plumes during the late afternoon hours when the animals were resting (either standing or lying down). Point measurements (expressed in ppm/m) were taken for six consecutive days and repeated once after every three months. The ratio of CH4 output per kilogramme DMI was not different in within-breed and between-breed in both seasons. Generally, the dry season recorded the highest CH4 output per kilogramme of live weight of cow. For example, Boran cows in parity 2 produced the highest output of 1.0 ± 0.04 g CH4 per kilogramme live weight of cow while Nguni cows in parities 1, 2 and 4 each produced 0.9 ± 0.04 g CH4 per kilogramme live weight of cow in the dry season. All the animals maintained optimal body condition scores in both seasons (ranging between the lowest of 3.2 ± 0.01 and the highest of 3.4 ± 0.01). Based on the results of the study, it is concluded that cows from both herds produced higher CH4 per kilogramme live weight of cow in the dry season while maintaining optimal body condition scores in both seasons.

The influence of living mass of the ukrainian black and white dairy breed cells in various everyday periods on their more dairy productivity

The connection of live weight of cows of Ukrainian black-and-white milk breed in the conditions of the Carpathian region of Lviv region in different ages with their subsequent milk productivity is established. It was investigated that live weight during the period of individual growth and development of animals has a significant impact on hopes, the content of fat in milk and the amount of milk fat. The difference in liveliness between cows with live weight at the first insemination to 300 and 361–380 kg for the first lactation was 249.3, for the second – 500.7 (P &lt; 0.002), for the third – 97.0 kg, and for the highest – 405.5 kg (P &lt; 0.01). Between cows with live weight at the first insemination of 361–380 and 401–420 kg, this difference was 185.1, 319.9 (P &lt; 0.05), 38.7 and 265.3 kg respectively (P &lt; 0.05). According to the results of the research, it can be stated that the optimum live weight during the period of raising cows at 6 months of age is a live weight of 160–180 kg, at 12 months of age it is 260–280 kg and the highest rates are obtained from cows that were growing at 18-months of age had a live weight of 360–380 kg. From the results of our research, it follows that for the Ukrainian black-and-white milk breed in the conditions of the Carpathian region of Lviv, the optimum live weight at the first insemination is 361–380 kg. The share of influence on milk production of live weight of cows during their growing period: at 6 months of age on hopes – 13.53–27.56%, on the fat content in milk – 15.18–39.70 and on the amount of milk fat 11.89–39.41%; at 12 months of age – respectively 24.65–37.84, 23.45–33.0 and 23.37–35.17%; in the 18-month – 27.38–40.93, 29.12–33.23 and 25.81–39.10%, and at the first insemination – 21.59–40.08, 31.32–39.99 and 21.52–39.88% at P &lt; 0.05–0.001. The probable correlation coefficients between the live weight of cows at 6 months of age and the reliance on second, third and highest lactation were 0.163–0.2253 and between live weight and fat content in milk – 0.110–0.233, between live weight at 12 months of age and the expectation for the second, the third and highest lactation – 0.233–0.240 and between the live weight and the amount of milk fat – 0.127–0.202, at the age of 18 months and for the second, third and highest lactation – 0.246–0.337 and between the live weight and the amount of milk fat – 0.116–0.308, and at the first insemination – 0.135–0.195 and 0.118–0.188 respectively at P &lt; 0.005 – P &lt; 0.001.

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

Dairy productivity of Simmental breed cows depending on their live weight during growing period

One of the main factors for effective breeding is the level of growth of repair young animals, which at all ages has a significant impact on animal health and their future productivity, duration of economic use and largely determines the efficiency of the dairy farming industry. It is important to know the potential capabilities of each animal's body since its birth, since the genetically programmed productivity of cows can only be realized if they are favorably grown at different ages at a young age. Therefore, the purpose of the research was to study the dependence of the milk productivity of the Simmental breed cows on their live weight during the period of growing. The research was carried out at LCC «Litinske», Drohobych district of Lviv region. The live weight of cows was studied at the age of 6, 12, 18 months, at the first insemination and after the first calving, and the assessment of milk productivity was carried out on the basis of diet, the fat content of milk and the amount of milk fat for the first, second, third and best lactation on the materials of the primary zootechnical accounting. It was established that the milk yield of cows, depending on lactation, were within the range of 3026.4–3685.8 kg, the fat content of milk – within 3.76–3.80% and the amount of milk fat – within the range of 113.6–139.8 kg. The live weight of the experimental animals at birth was 32.5, at 6 months – 185.9, in 12 months – 302.3, in 18 months – 405.2, at the first insemination – 396.9 and in the first calving – 514.7 kg It should be noted that the first fertile insemination of Simmental heifers occurred at the age of 19.7 months, and their first calving – at the age of 29.0 months. The highest diet and the amount of milk fat in cows were observed for their live weight at birth 33–34 kg, at 6 months of age – 171–190, in 12 months – 291–300, in 18 months – 401–415, at the first insemination – 416–430 and in the first calving – 501–530 kg. The correlation coefficients of the live weight of animals at young age and their subsequent milk productivity, depending on the age and lactation of the animals, were within the range of 0.18–0.24, and the influence of live weight of heifers on their subsequent milk productivity – within 12.3–20.1%.

Divergent breeding values for fatness or residual feed intake in Angus cattle. 6. Dam-line impacts on steer carcass compliance

The present study determined the impact of maternal genetics for estimated breeding values for rib fat (High-Fat, Low-Fat) or residual feed intake (RFI; High-RFI, Low-RFI) on the carcass compliance of Angus steer progeny when reared pre-weaning under High or Low-Nutrition and post-weaning under various finishing system (grazing versus short-term feedlot). The dams were joined to sires of similar genetic background (close to average estimated breeding values) and sires were rotated among all dam genotypes, with herds located at either Struan Research Centre, near Naracoorte in the south-east of South Australia, or Vasse Research Station, in the south-west of Western Australia. The breeding herd was part of the Beef CRC maternal productivity project and cows were managed under either High or Low-Nutrition, achieved by adjustments to stocking rate in rotational grazing systems and supplementary feeding, so as to maintain ~20% difference in cow liveweight. The steer progeny were weaned at ~7 months of age, with individuals from both pre-weaning nutritional treatments being treated the same from then on at each site. Steers from Struan Research Centre in South Australia born in 2008 and 2009 were sold and grown out on pasture on a local commercial property. Steer calves born in 2010 at Vasse remained on the station where they were backgrounded on hay, followed by a short period (111 days) total mixed ration containing 40% grain. In the first year, steers from Struan (n = 58) were slaughtered together at ~2 years of age, and in the second year (n = 85), consigned to six slaughter groups as their ultrasound-scanned subcutaneous P8 (rump) fat reached 7 mm and their liveweight exceeded 550 kg. Steers from Vasse (n = 101) were slaughtered at ~12 months of age, all on the same day. High-Fat-line dams produced steers with carcasses with greater P8 fat than did Low-Fat-line dams at both sites. At Struan, when the 2008-born steers were slaughtered together, more steers from Low-Fat dams failed to meet minimum fat specifications, than steers from High-Fat dams (28% vs 9% respectively). The steers born in 2009 at Struan all met processor fat specifications but steers from the Low-Fat dams took longer to reach the fat threshold, and so had greater carcass weight, but attracted more price penalties because of increased dentition. All steers from Vasse met minimum requirements for fat, with none penalised for dentition. Vasse steers from High- or Low-RFI dams performed in a manner similar to that from High- and Low-Fat dams, respectively, in that the High-RFI group produced fatter carcasses than did the Low-RFI group. Steers reared under low pre-weaning nutrition weighed less at weaning than did those on High-Nutrition, but had higher weight gains after weaning, although insufficient to result in the same carcass weight. The results showed that commercial cattle producers need to be aware of the balance and trade-off among fat breeding value, effect of pre-weaning nutrition and post-weaning growth required to ensure their cattle meet market specifications and to avoid price penalties.