Milk Yield Of Cows Research Articles

Association Between Body and Udder Measurement Traits and Milk Yield of Holstein Cows

The association between body and udder measurements can be used towards the improvement of milk yield. Hence, this study aimed to identify the udder measurement traits and body measurement traits that may be used by farmers to increase milk yield of Holstein cows. The study was conducted at Limpopo Dairy Farm in Makhado Local Municipality at Louis Trichardt, Limpopo Province, South Africa where a total of 50 lactating Holstein cows were used. Pearson’s correlation technique was used for data analysis. Findings between body measurement traits and milk yield showed that milk yield had a highly positive significant (p ˂ 0.01) correlation with rump height (r = 0.55), and positive significant (p < 0.05) with withers height (r = 0.44) and body length (r = 0.42). Results between udder measurement traits and milk yield showed that milk yield had a highly positive significant (p < 0.01) correlation with udder length before milking (r = 0.57), udder circumference before milking (r = 0.55) and udder circumference after milking (r = 0.51) The results also showed that milk yield had a positive significant (p < 0.05) correlation with teat diameter before milking (r = 0.30), teat length before milking (r = 0.31), teat circumference before milking (r = 0.36) and udder length after milking (0.47). The findings imply that all traits correlated with milk yield can be used to enhance milk yield of Holstein cows through selection during breeding. Vol. 10, No. 3, December 2023: 335-340

CGA alleviates LPS-induced inflammation and milk fat reduction in BMECs through the NF-κB signaling pathway

Mastitis is an easy clinical disease in dairy cows, which seriously affects the milk yield and quality of dairy cows. Chlorogenic acid (CGA), a polyphenolic substance, is abundant in Eucommia ulmoides leaves and has anti-inflammatory and anti-oxidative stress effects. Here, we explore whether CGA attenuated lipopolysaccharide (LPS)-induced inflammation and decreased milk fat in bovine mammary epithelial cells (BMECs). 10 μg/mL LPS was used to induce mastitis in BMECs. QRT-PCR, Western blotting, oil red O staining, and triglyceride (TG) assay were used to examine the effects of CGA on BMECs, including inflammatory response, oxidative stress response, and milk fat synthesis. The results showed that CGA repaired LPS-induced inflammation in BMECs. The expression of IL-6, IL-8, TNF-α, IL-1β, and iNOS was decreased, and the expression levels of CHOP, XCT, NRF2, and HO-1 were increased, which reduced the oxidative stress level of cells and alleviated the reduction of milk fat synthesis. In addition, the regulation of P65 phosphorylation by CGA suggests that CGA may exert its anti-inflammatory and anti-oxidative effects through the NF-κB signaling pathway. Our study showed that CGA attenuated LPS-induced inflammation and oxidative stress, and restored the decrease in milk fat content in BMECs by regulating the NF-κB signaling pathway.

Влияние антиоксидантов, энергокорма и йода на адаптацию коров к высоким температурам среды, молочную продуктивность и воспроизводство

Two studies were conducted. In the 1st there are 3 groups of black-and-white cows of 9 heads each. One was the control, received the main diet (BR), the 2nd (experimental 1) received energy feed (EF) containing 23.6 MJ/kg of metabolizable energy in 150 and 300 ml in addition to the EF, the 3rd (experimental 2) additionally received 0.5 and 1.5 g of organic iodine (OI) and 1 g of dihydroquercetin (DHQ) head/day, respectively, during the dry and lactation periods in the spring and summer months, characterized by thermoneutral and high summer temperatures. Milk productivity and milk quality in cows during the spring-summer period had differences between groups. In cows of the control group, on average, over 5 months of lactation, the average daily milk yield was 22.7 kg with a fat content of 3.79% and protein of 2.94%: in cows of the 1st experimental group 21.6, 3.90, 3.02 and the second experimental group 20.8, 3.89 and 3.04, respectively, with a slightly higher average daily milk yield in cows of the control group by 1.1 and 1.4 kg compared to. cows of the 1st and 2nd experimental groups, their fat and protein content in milk was lower by 0.11 and 0.08 % pp in relation to the cows of the 1st experimental group and by 0.10 and 0.10%, respectively, compared to cows of the 2nd experimental. As a result, the content of total dry matter in milk was higher in cows of the experimental groups, which amounted to 12.70 and 12.54% compared to 12.15 % in the control group. The second study examined the effects of antioxidants on reproductive performance in cows. For the experiment, 3 groups of black-and white cows aged 3-5 years, 15 heads each, were formed, the cows of the 1st group were control. Cows of the 2nd and 3rd groups were intramuscularly injected with 20 ml of the selenium preparation Gabivit-Se with the addition of 250 and 500 mg of DHQ, respectively, twice with an interval of 7 days. Treating cows with antioxidants significantly improved the physiological, biochemical and reproductive performance of cows. Treatment of cows with Gabivit-Se + 500 mg DHQ was more effective.

A retrospective study on the effects of dry period length on milk yield and postpartum health in Holstein dairy cows.

We retrospectively analyzed the effects of dry period length (DPL) on milk yield and postpartum health using 152 commercial dairy farm data, including 46,228 dairy cows in Hokkaido, Japan, and examined the optimal DPL. The DPL was divided into eight categories: ≤25, 26-35, 36-45, 46-55, 56-65 (reference), 66-75, 76-85, and ≥86 d. The total milk yields (the sum of milk yield during the 55 d before and the 305 d milk yield after calving) of cows with DPL of ≤55 d did not differ from the reference group. Cows with DPL of ≤55 d had lower odds ratios (OR) of a displaced abomasum (DA), ketosis, milk fever (MF), and abnormal milk fat-to-protein ratio but had higher puerperal fever (PF) and stillbirth ORs than the reference group. Cows with a DPL of 46-55 d had the lowest PF and stillbirth ORs among the short DPL categories. The extremely short (≤25 d) and long (≥86 d) DPL increased the ORs of mastitis and abnormal liner score of somatic cell counts (SCCs) compared with the reference group. We conclude that shortening DPL can reduce postpartum health problems without reducing milk yield and that the optimal DPL is 46-55 d.

Effect of dietary Chinese herbal preparation on dry matter intake, milk yield and milk composition, serum biochemistry, hematological profile, and reproductive efficiency of Holstein dairy cows in early postpartum period.

The present study investigated the effects of various inclusion levels of dietary Chinese herbal medicine (CHM) preparation on feed consumption, milk yield and milk composition, serum biochemistry, hematological profile, and reproductive efficiency of Holstein dairy cows. A total of 117 lactating Holstein cows were randomly divided into four groups as control (n = 27; without CHM supplementation) and treatment groups CHM-0.5 (n = 31), CHM-0.75 (n = 29), and CHM-1 (n = 30) fed diet supplemented with 0.5, 0.75, and 1 kg/cow/d for 30 days, respectively. The study began at d 20 postpartum (d 0 of the study). At d 50 postpartum, the cows in all groups were subjected to estrus synchronization using a modified Ovsynch protocol (GPGMH) and observed for reproductive variables. Feed intake, milk yield and milk composition, serum biochemistry and hematological profile, and reproductive efficiency were measured. A significantly higher milk yield with improved milk lactose, milk protein and milk fat were found in the CHM-0.75 group compared to the other groups (p < 0.05). Besides, the estrus response, ovulation rate, ovulatory follicle diameter, and pregnancy rate increased in CHM-0.75 compared to CHM-0 or CHM-0.5 group (p < 0.05). The serum metabolites (glucose, AST, arginine, BUN, and NO) showed variations among the treatment groups at different time points (synchronization, AI, or post-AI). In conclusion, CHM supplementation improves the milk yield, milk composition, and serum metabolites in dairy cows. Daily supplementation of 0.75 kg CHM before the GPGMH protocol application enhances the reproductive traits in dairy cows under summer conditions.

Effects of nanoselenium on the performance, blood indices, and milk metabolites of dairy cows during the peak lactation period.

To compare the impact of nanoselenium and sodium selenite on the performance, blood indices, and milk metabolites of dairy cows during the peak lactation period, two groups of dairy cows under the same conditions were selected as the control group (CON group) and treatment group (NSe group) for a 38-day (10 days for adaptation and 28 days for sampling) experiment. The control group (CON) was provided a basal diet +3.3 g/d of sodium selenite (purity1%), whereas the nanoselenium group (NSe) was offered the same diet +10 mL/d of nanoselenium (selenium concentration 1,500 mg/L). The results showed that NSe significantly increased the milk yield, milk selenium content, and feed efficiency (p < 0.05), but had no significant effect on other milk components (p > 0.05). NSe significantly increased blood urea nitrogen (BUN) and alkaline phosphatase (ALP) (p < 0.05), but had no significant effects on malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), blood total antioxidant capacity (T-AOC), or blood selenium (p > 0.05). In addition, the nontargeted metabolomics of the milk was determined by LC-MS technology, and the differentially abundant metabolites and their enrichment pathways were screened. According to these findings, NSe considerably increased the contents of cetylmannoside, undecylenoic acid, 3-hydroxypentadecanoic acid, 16-hydroxypentadecanoic acid, threonic acid, etc., but decreased the contents of galactaric acid, mesaconic acid, CDP-glucose etc. Furthermore, the enriched metabolic pathways that were screened with an impact value greater than 0.1 included metabolism of niacin and niacinamide, pyruvate, citrate cycle, riboflavin, glycerophospholipid, butanoate and tyrosine. Pearson correlation analysis also revealed a relationship between different milk metabolites and blood selenium, as well as between milk selenium and blood biochemical indices. In conclusion, compared with sodium selenite, nanoselenium improves the milk yield, feed efficiency, and milk selenium content of dairy cows and regulates milk metabolites and related metabolic pathways in Holstein dairy cows during the peak lactation period, which has certain application prospects in dairy production.

Effect of dietary supplementation of plantain herb, lemongrass and their combination on milk yield, immunity, liver enzymes, serum, and milk mineral status in dairy cows

Effect of dietary supplementation of plantain herb, lemongrass and their combination on milk yield, immunity, liver enzymes, serum, and milk mineral status in dairy cows

Supplementing a Bacillus-based direct-fed microbial improves feed efficiency in lactating dairy cows.

This experiment was conducted to evaluate the effects of feeding a Bacillus-based direct-fed microbial (DFM) on performance and nutrient digestibility of lactating dairy cows. Seventy-six lactating (42 ± 6 days in milk[DIM]) Holstein-Friesian primiparous and multiparous cows were enrolled to a 16-wk experiment. Cows were blocked by lactation number and DIM and within blocks, assigned to 1 of the 2 treatments: 1) basal partial-mixed ration (PMR) without DFM addition (n = 38; CON) or 2) basal PMR with the addition of 3g/head/d of a DFM containing B. licheniformis 809 and B. subtilis 810 (n = 38; BOVACILLUS, Chr. Hansen A/S, Hørsholm, Denmark; DFM). The DFM was mixed in a protein-based pellet, whereas the CON group was fed the same pellet without DFM (0.6kg/cow/d). The PMR contained (dry matter [DM] basis) 50% of forage and 48% of a concentrate feed based on corn meal, soybean meal, wheat meal, wheat middlings, and a mineral-vitamin premix, with the remaining part of the diet being represented by the pellet used as a carrier for the treatments (CON and DFM). Dry matter intake (DMI), milk yield, and production efficiency were recorded daily, whereas milk protein and fat concentrations were recorded using electronic milk meters. An additional milk sample was collected every second week of the study for milk composition. On week 15 of the study, fecal samples were collected from each cow for apparent nutrient digestibility calculation. All data were analyzed using the MIXED procedure of SAS (version 9.4; SAS Inst. Inc., Cary, NC). No treatment effects were observed on cow final body weight, daily DMI, milk yield, energy-corrected milk (ECM), ECM efficiency, milk composition (yield or content), and somatic cell count (SCC) (P ≥ 0.12). However, cows fed DFM had a greater feed and N efficiency (P ≤ 0.03) compared to cows fed CON. Moreover, DM digestibility tended to be greater for DFM-fed cows when compared to CON (P = 0.10), whereas no further nutrient digestibility differences were observed (P ≥ 0.24). In summary, supplementing a DFM containing Bacillus licheniformis and B. subtilis benefited feed efficiency of lactating dairy cows fed a PMR, while also tending to improve the digestibility of DM.

Эффективность применения целлюлозолитического ферментного комплекса в составе энергокорма в питании молочных коров

The research was carried out on 2 groups of dairy cows of 30 heads each on a farm with the formation of technological groups according to calving dates and milking on a unit with individual milk yield accounting. The cows of the experimental group, in the period two weeks before calving and for 2 months after calving, were added to the diet, respectively, 150 and 300 ml/head/day of energy feed based on propylene glycol and glycerol with a complex of cellulase, xylase, β-gluconase and glucoamylase enzymes. activity (EFEC). The main diet consisted of traditional feed and was designed to produce an average daily milk yield of 25 kg of milk. EFEA had virtually no effect on the pH and ammonia content in rumen chyme, but increased the VFA content in it by 3.6 %. It had no effect on the total microbial mass, but reduced the ciliate population by 23.5 % and increased the bacterial population by 27.8 %. EFEC had a positive effect on protein-nitrogen metabolism, functional state of the liver, antioxidant activity, hormonal status and hematology. As a result, during 3 months of lactation, the average daily milk yield of cows in the experimental group was 19.9, 20.9 and 21.1 kg of milk (P&lt;0.001), which was 13.0 higher than in the control. 9.4 and 16.5 %, respectively, but at the same time there was a decrease in fat and protein content in milk.

Оценка состояния молочного скотоводства в России

An analysis of the development of dairy cattle breeding shows that the number of cattle in the country is decreasing every year (from 19 793.9 thousand heads in 2010 to 17 488.6 thousand heads in 2022), including cows (from 8713.0 thousand in 2010 to 7734.7 thousand in 2022). At the same time, from 2010 to 2022, the gross milk yield in the country increased from 31 507.8 thousand to 32 983.7 thousand tons. The article identifies the features and contribution of various forms of management in milk production. The growth of gross milk production is ensured by increasing the milk yield of cows. Here, an important role belongs to government support measures that contribute to an increase in the average milk yield per cow. The current trends are typical for all regions of the country with highly developed dairy cattle breeding. In recent years, the ratio of the breed composition of the dairy cows has changed significantly, in 2010-2022 the share of Holstein cows increased by more than 50%. At the same time, a significant genetic potential in dairy cattle breeding remains untapped. The number of breeding animals in breeding farms is decreasing. At the same time, the import of breeding cattle is decreasing, and its breed diversity is also decreasing – from 7 to 5 breeds. Significant efforts are to be made both to increase the number of cattle in the country and to improve the quality of work with the dairy herd.

АНАЛИЗ ЭКСПЛУАТАЦИОННЫХ ХАРАКТЕРИСТИК ПРИБОРОВ УЧЕТА МОЛОКА

The foreign and domestic individual milk yield accounting devices analysis is carried out. The dairy industry development’s main directions for production rate’s and milk quality increasing are given. The development of these areas is impossible without for milk collecting, accounting and primary processing. Milk accounting on modern domestic and foreign farms can be both group and individual. At group accounting, milk from cows enters into a cooling tanker, and then, through a metering device, into the tanks of vehicles for transportation for enterprises and plants processing. This is a simple and convenient method using only one milk meter, however, by this accounting method, the milking process control impossible. The individual milk yield counters’ using is important for particular cow milk yield predicting for cow health preserving due to milking cups’ absence overexposing. Also, individual milk accounting allows to separate mastitis infected milk from the healthy cows’ milk, that allows to reject only part of farmer milk producing, and not the entire batch, as it would be in the case with group accounting. A brief description of the types of sensors for individual and group milk metering from foreign and domestic producers is presented. An advantages and disadvantages of the considered milk metering devices comparative assessment is given. It is concluded that there is a necessity developing for a system that will meet the following requirements: the ability with a milk-and-air mixture working; device’s high autonomy; construction’s simplicity; high accuracy. Based on the analysis of milk meter designs, it can be argued that the most design promising should be based on the capacitive principle, when the milk-and-air mixture flow will change the electrical capacitance

The coexistence of several microbial species at the same site of bovine mammary gland parenchyma infection and their mixed infections

&lt;b&gt;The purpose of this study was to analyse both negative results of bacteriological cultures and the coexistence of several pathogens at the same intramammary inflammatory focus within bovine udder parenchyma in order to compare the health status of cows’ udders in 1985 and 2021. Mastitis was diagnosed on the basis of anamnesis, clinical inspection of the udder, milk quality, and somatic cell counts (SCC on the Fossomatic 5000-FC). In 1985, joint bacteriological and mycological diagnosis was based on the guidelines established for bovine mastitis by FIL-IDF (1971), while for 2021, it was based on the National Mastitis Council (NMC) laboratory Handbook on bovine mastitis (Hogan et al., 1999). In the first study (1985), mainly the genus Staphylococcus was isolated, but at present other species may be involved in cases of mastitis. In both periods, both subclinical and clinical cases were registered. In addition, the milk yield of cows was observed to increase over time, with concomitant deterioration of mammary gland immunity. The phenomenon of biofilms was documented in the study, which may be explained not only by the low efficacy of antibiotic therapy against udder disease but also by impaired immunity in cows, as the lymphocytes trapped in the biofilm matrix were inactive with respect to both cellular and humoral responses.

The Effect of Supplementing White Sweet Lupine Grain Meal (Lupinus albus L.) on Blood and Milk Metabolites, Milk Yield, and Quality of Dairy Cows in Ethiopia

Feed is the cornerstone of dairy production, serving as a crucial input for sustainable milk production. This trial aimed to investigate the effect of white sweet lupine grain meal inclusion on feed intake, blood and milk metabolites, milk yield, and quality. The experimental cows had a parity of 2±0.71 (mean ± SD), a daily milk yield of 12.72 ± 0.9, and an average body weight of 412.6 ± 21.5 kg. The varying proportions of treatment diets were: 75, 50, 25 and 0% (T1, T2, T3 and T4) treatment groups respectively. Data collected during the study were subjected to analysis of variance to determine significant differences. Cows fed diet T1 showed a better dry matter (10.39 kg/day), organic matter (7.31 kg/day), nitrogen (2.42 kg/day), and NDF intakes (3.75 kg/day) that had significant difference on (p&lt;0.05). When lupine inclusions dropped from 75 to 50 and even to 25%, the N digestibility decreased from 76.63, 70.66, and 65.6%, respectively, and the digestibility of N in all treatment diets significantly decreased (p &lt; 0.01). Once more, cows fed T1 diet had the highest (p&lt;0.01) plasma glucose concentration (116.81 mg/dl) among the four experimental groups. Cows fed T2 and T4 diets showed significant variation at (p&lt;0.05) in plasma glucose levels, with values of 108.7 and 110.16 mg/dl, respectively. Cows fed T1 had relatively lower plasma beta-Hydroxybutyric acid and non-esterified fatty acid concentrations (p&lt;0.05) than others, with mean values of 3.23 and 1.28 mg/dl respectively. The partial inclusion of white sweet lupine grain meal up to the level of 75% is highly suggested as a better alternative feed source.

INFLUENCE OF LINEAGE ON THE MILK PRODUCTIVITY OF COWS OF DOMESTIC BREEDS WITH DIFFERENT HERITAGE OF THE HOLSTEIN BREED

The results of research on the influence of the linear belonging of cows of domestic breeds and the percentage of conditional blood of the Holstein breed in their genotype on the manifestation of signs of milk productivity during four lactations are shown. The research was carried out on cows of the Ukrainian Black-and-White Dairy breed of Bell’s 1667366.74, Valiant’s 1650414.73, Elevation’s 1491007.65, Elbrus’s 897.78, Marshall’s 2290977.95, S. T. Rocket’s 252803, Starbuck’s 352790.79 and Chief’s 1427381.6 genealogical formations, which were used in the production of milk in 9 different herds under control regions of Ukraine. Representatives of the Ukrainian Red-and-White Dairy breed belonged to the Valiant’s 1650414.73, Elevation’s 1491007.65, Inhancer’s 343514.77, Cavalier’s 1620273.72, Cadillac’s 2046246.87, Hanover’s 1629391.72 and Chief’s 1427381.62 lines and were concentrated in 10 controlled herds. According to conventional blood, cows of both breeds were divided into 4 genotypic groups: 50.0–74.9% (I group), 75.0–87.4% (II), 87.5–93.6% (III) and 93.7–100% (IV). It was determined by the significant variability of milk yield of cows of both breeds in 305 days of the first to fourth lactation, which is caused by the studied genotypic factors. Only female offspring of both breeds of the Chief’s 1427381.62 line clearly increased hope with increasing Holstein heritability in their genotype for each of the four lactations. A reliable influence of lineal ownership on the manifestation of signs of milk productivity of cows was revealed. The percentage of conventional blood of cows of the Holstein breed is not a stable value for the population, since there is a constant absorption of the available breeding material by representatives of foreign origin, therefore it is not advisable to focus on a certain genotypic group when breeding cattle, with the exception of highly Holsteinized animals. It was concluded that selective crossing of cattle of domestic breeds with Holstein does not contribute to obtaining high milk productivity even in high-blooded animals close to the improvement breed, regardless of their lineal affiliation. Among the investigated genotypic factors, it is recommended to focus on the line when improving livestock of domestic breeds, as it has a significant impact on the productivity of cows and is a permanent constant in the breed hierarchy.

Pedigree base of brown Swiss cattle breed in the Smolensk region

The current state by the end of 2020of the Brown Swiss breed of cattle in pedigree farms of the Smolensk region was studied. The average milk yield in herds for the last completed lactation is 4045 – 6626 kg of milk, the yield of milk fat and protein is 158 – 268 kg and 134 – 236 kg, respectively. In the best farm of the SPK “Druzhba”, the average milk yields of cows for the highest lactation exceed 7000 kg of milk, eight animals have record results of 10016 – 11720 kg. Cows are born from fathers of high breeding value. The average milk yield mothers of fathers in herds is 9767 – 12333 kg. The average age of cows according to the last completed lactation in the studied herds is 2.3 – 3.9 lactation. The age of the first fruitful insemination in the best farm is 16.5 months. From 87.8 to 98.3% of cows belong to lines of foreign origin.

Экономическая эффективность инновационных разработок, направленных на увеличение производства молока

Purpose. Assessment of the economic efficiency of using scientific developments in milk production. Materials and Methods. Scientific and economic experiments were carried out in three farms in the Volgograd region: breeding farm named after Lenin of Surovikinsky district; Agricultural Enterprise "Donskoye" LLC of Kalachevsky district and JSC "named after Kirov" of Staropoltavsky district. The object of research is lactating cows of Holstein, Red Steppe and Black-and-White breeds. The amount of fat, protein and other indicators contained in cows’ milk was determined in the conditions of the complex analytical laboratory of VRIMMP using standard methods. The calculation of economic indicators was carried out on the basis of data from summary reports on the results of livestock judgement, cards of breeding farms using methods of a systematic approach, analysis and calculation. Results. At the breeding farm named after Lenin, thanks to the use of lactulose-based feed additives in feeding cows, the milk yield of cows in the experimental groups increased by 5.59 and 8.09%, respectively, the fat content of milk – by 6.91 and 9.57%, protein – by 5.01 and 6.35 % compared to the control group. More profit was received from cows of experimental groups I and II compared to analogues in the control group by 1473.2 and 2131.0 rubles. The experimental groups exceeded the control group in terms of production profitability by 1.2 and 2.1%. In Agricultural Enterprise "Donskoye" LLC, the milk yield of cows during the highest lactation increased until the 3rd calving, and its increase was 1474.1 kg (15.4%). The animals that showed the greatest productivity (11,000.8 kg) after the first calving were 0.3 lactation higher than the animals that showed the greatest productivity in the second lactation. The introduction of modern scientific approaches made it possible to achieve a level of production profitability in 2022 of 30.0%, which is 2.6% higher than in 2018. At JSC "named after Kirov" produced 400 kg more milk per lactation, or 5.23%; profit – by 2980 rubles, or 8.5%; production profitability increased by 2.2%. Conclusion. The implementation of new scientific developments and intensive technologies at large dairy complexes makes it possible not only to improve the quality of the resulting dairy products, increase the productivity of animals, but also the overall profitability of industrial milk production.

The association between calf birth weight and the postcalving performance of its dairy dam in the absence of dystocia

The objective of the study was to quantify the association between the birth weight of a calf and the subsequent performance of its dairy dam in the absence of any recorded calving assistance. A total of 11,592 lactation records from 4,549 spring-calving dairy cows were used. The association between a series of quantitative cow performance metrics (dependent variable) and calf birth weight (independent variable) was determined using linear mixed models; logistic regression was used where the dependent variable was binary. Nuisance factors in the models were calf sex, heterosis coefficient of both the cow and calf, dry period length immediately before the birth of the calf, cow age at calving relative to the median cow age per parity, breed proportion of the cow, cow live weight between 100 and 200 d of lactation relative to the mean cow weight per parity, and contemporary group. Calf birth weight was included in the model as either a continuous or a categorical variable. Primiparous and multiparous cows were analyzed separately. Mean (SD) calf birth weight was 36.2 (6.8) kg. In primiparous cows, calf birth weight was associated with milk yield in the first 60 d of lactation, calving to first service interval, calving body weight (BW), and both nadir BW and body condition score (BCS). In multiparous cows, calf birth weight was associated with total milk, fat, and protein yield in the first 60 and 305 d of lactation, peak milk yield, total milk solids, both calving and nadir BW, and BCS loss from calving to nadir. Relative to primiparous cows that gave birth to calves weighing 34 to 37 kg (i.e., population mean), their contemporaries who gave birth to calves that weighed 15 to 29 kg produced 9.82 kg more milk in the first 60 d of lactation, had a 2-d shorter interval to first service, and were 8.08 kg and 5.51 kg lighter at calving and nadir BW, respectively; the former was also 0.05 units lower in BCS (5-point scale, 1 = emaciated and 5 = obese) at nadir. Relative to multiparous cows that gave birth to calves that were 34 to 37 kg birth weight, multiparous cows that gave birth to calves that were 15 to 29 kg yielded 59.63 kg, 2.44 kg, and 1.76 kg less milk, fat, and protein, respectively, in the first 60 d of lactation; produced 17.69 kg less milk solids throughout the 305-d lactation; and were also 10.49 kg lighter at nadir and lost 0.01 units more BCS to nadir. In a separate series of analyses, sire breed was added to the model as a fixed effect with and without calf birth weight. When calf birth weight was not adjusted for, 60-d milk yield for multiparous cows who gave birth to calves sired by a traditional beef breed (i.e., Angus, Hereford) produced 59.63 kg more milk than multiparous cows who gave birth to calves sired by a Holstein-Friesian. Hence, calf birth weight is associated with some subsequent dam performance measures; however, where associations do exist, the effect is biologically small.

The relationship of milk productivity and reproductive functions of Holstein cows

Relevance. Providing the population of the country with high–quality food products of its own production is the main task facing the employees of the agro-industrial complex of the country. One of these products is milk. The bulk of milk is obtained from cows of the dairy productivity direction. Currently, in the Sverdlovsk region, more than 75% of the total number of cattle belongs to the Holstein breed, created by the absorption of domestic black-and-white cattle by the Holstein. The study of economically useful signs of dairy cattle of the Holstein breed is relevant and has practical significance.Methods. The research was carried out in breeding reproducers for breeding Holstein black-and-white cattle of the Sverdlovsk region. The evaluation included all cows that completed the first lactation in 2020-2021. Milk productivity was assessed by control milkings, milk quality indicators: MJ and MDB in milk in an average milk sample from each cow — once a month in the dairy laboratory of “Uralplemcenter” LLC.Results. As a result of the conducted studies, it was found that the highest productivity indicators in cows were on the 3rd lactation — both for the entire lactation and for 305 days of lactation. Starting from the 4th lactation, there is a decrease in milk yields — from 0.3% (5th lactation) to 8.5% (8th lactation). Further, fluctuations in milk yields have been established in the direction of increasing or decreasing, which is explained by a decrease in the number of animals used in farms for a long time. Coefficient of reproductive capacity for all lactation (up to and including the 12th) stable and is 0.89–0.91, that is, there is a problem with the reproduction of breeding reproducers in dairy cattle herds. No relationship between reproductive functions and milk yield of cows has been established.

EFFECT OF GRADED LEVELS OF CONCENTRATE SUPPLEMENTION ON MILK YIELD AND COMPOSITION OF GRAZING WHITE FULANI COWS. IN MAYO-BELWA SUB-HUMID, NIGERIA

A 98-day feeding trial was conducted at Sebore Farm along Mayo-Belwa-Ngurore road, Mayo-Belwa Local Government Area (LGA) of Adamawa State to determine the effect of graded levels of concentrate supplementation on milk yield, milk composition, body conformation and live weight changes of White Fulani cows. The objective of this study was to determine the extent to which supplementary feeding improves milk yield and quality of lactating White Fulani cows grazed on mixture of Andropogon gayanus (Gamba grass) and Panicum maximum (Guinea grass). Twelve White Fulani cows weighing average of 250±2.217kg with average age of 5±1.5 years between 2nd and 3rd lactations, were subjected to four dietary treatments: T1 (control), T2 (3kg concentrate), T3 (4kg concentrate) and T4 (5kg concentrate) per head per day. The treatments consisted of three replicates in a randomized complete block design (RCBD) experiment. Milk yield was measured with a cylinder which is graduated in litres. The chemical composition of milk was carried out to determine milk protein, fat, total solids, ash vitamins, minerals, pH and density. The live-weight changes were calculated by subtracting the initial weight from the final weight. The result indicated that milk yield was significantly (P&lt;0.05) different among treatments with T4 showing the highest milk yield of 1.89±0.059 litres per day while T1 had low values of 0.78±0.013 litres per day. The live-weight changes showed a significant (P&lt;0.05) increase with increasing level of supplementation up to 4kg at (T3) but there was no significance (P&gt;0.05) difference between treatments 3 and 4. T2, T3&amp; T4) had significantly (P&lt;0.05) improved milk yield and live weight gain than the control. The study revealed that supplementary feeding of grazing White Fulani cows with concentrate was beneficial. Treatment 4 with 4kg supplementation is therefore recommended based better on milk yield and live-weight gain

Effects of heat stress on feed intake, milk yield, milk composition, and feed efficiency in dairy cows: A meta-analysis

Heat stress compromises dairy production by decreasing feed intake and milk yield, and it may also alter milk composition and feed efficiency. However, little information is available for evaluating such effects across different levels of heat stress and cows enrolled in heat stress studies. The objectives of this study were to evaluate the effects of heat stress on dry matter intake (DMI), energy-corrected milk (ECM), milk composition, and feed efficiency (kg ECM/kg DMI) and to investigate the relationship between such effects and heat stress intervention and animal characteristics by using meta-analytical approaches. Data from 31 studies (34 trials) fulfilled the inclusion criteria and were used for analysis. Results showed that heat stress decreased DMI, ECM, and milk protein concentration, but did not alter milk fat concentration or feed efficiency. Meta-regression confirmed that such reductions in DMI and ECM were significantly associated with increasing temperature-humidity index (THI). Over the period of heat stress, for each unit increase in THI, DMI and ECM decreased by 4.13% and 3.25%, respectively, in mid-lactation cows. Regression models further revealed the existence of a strong interaction between THI and lactation stage, which partially explained the large heterogeneity in effect sizes of DMI and ECM. The results indicated a need for more research on the relationship between the effect of heat stress and animal characteristics. This study calls for the implementation of mitigation strategies in heat-stressed herds due to the substantial decrease in productivity.