Milk Yield Of Cows Research Articles

Milk Yield Prediction and Economic Analysis of Optimized Rearing Environment in a Cold Region Using Neural Network Model

The milk yield of dairy cows in a non-stressed state in the cold region in China is lower during cold seasons. In this study, the correlations between indoor environmental factors and milk production were analyzed. Temperature, relative humidity, and light intensity were found to be the main factors affecting milk yield. The warning values of these factors for lower milk production were 5 °C, 60%, and 300 lx, respectively. A neural network model predicting milk yield based on environmental factors was established, and the optimal model parameters were determined, resulting in a high accuracy of R2 = 0.802. This model was used to investigate the optimal measure for improving the indoor environment, which helps to increase milk production and economic benefits, including LED lights, heating radiators, and dehumidifiers. In conclusion, each type of device led to the growth of milk yield, reaching 2.341, 1.706, and 1.893 kg cow−1 Day−1. The combination of heating radiator and LED light resulted in the highest increased net benefit of 16.802 CNY cow−1 Day−1. This is the first time that a neural network model was successfully built to predict milk yield based on climatic features which was also applied to economic analysis of indoor environment improvement for dairy barns in extreme cold regions.

Realization of the genetic potential of Yaroslavl cows

The purpose of research was determining the degree of realization of the genetic potential of Yaroslavl cows of different genotypes. It was found out that the formation of productive traits in improved genotypes and purebred animals is different. The genetic potential of cows of the improved genotype of the Yaroslavl breed in milk yield exceeded purebred animals by 2,460 kg or by 51.9%. Milk yield of cows of the improved genotype were higher by 718-1574 kg than those of purebred Yaroslavl cattle, however, the degree of realization of the genetic potential was lower and amounted to 55.2-76.8%. Purebred cows of the Yaroslavl breed had a high degree of realization of the genetic potential for milk yield throughout the entire productive use - 68.0-82.2%, which indicates their better adaptive ability to the conditions of feeding and maintenance.

Assessment of the effects of prepartum anti-inflammatory therapies on type 1/type 2 immunity ratio using a rapid blood test

The objective of this study was to assess (1) the effects of prepartum administration of anti-inflammatory therapies on type 1/type 2 immunity ratio using a rapid blood test (D2Dx immunity test; Nano Discovery Inc.), and (2) correlations between rapid blood test scores and daily milk yield in Holstein dairy cows. At 14 d before the expected calving date, cows (n = 64) and heifers (n = 23) were blocked by body condition score (optimal = 3.25-3.5; high ≥3.75) and parity (nulliparous, parous), and randomly allocated to one of 3 treatment groups (1) ASA (n = 29) = receive one oral treatment with administration of acetylsalicylic acid (4 boluses; 480 grain/bolus); (2) MEL (n = 31) = receive one oral administration with meloxicam (1 mg/kg of body weight), or (3) PLC (n = 27) = receive one oral treatment with 4 gelatin capsules filled with water. Blood samples were collected weekly starting 1 wk before treatment until 3 wk after calving for assessment of type 1/type 2 immunity ratio using a rapid blood test (i.e., D2Dx immunity test). A higher D2Dx score corresponds to a higher type 1/type 2 ratio. Furthermore, blood samples were collected within 72 h before and after calving by farm personnel. Daily milk yield for the first 60 d in milk (DIM) was collected from on-farm computer records. The data were analyzed using MIXED procedure of SAS (SAS Institute Inc.) as a randomized complete block design. On average enrolled cows received treatment administration 10 d before the actual calving date (standard deviation = 5.10 d). There was a tendency for a treatment by day interaction. Cows treated with ASA had higher type 1/type 2 ratio within 3 d after calving compared with MEL and PLC cows (ASA = 0.065 ± 0.002; MEL = 0.059 ± 0.002; PLC = 0.053 ± 0.002). Similarly, ASA and MEL cows had a higher type 1/type 2 ratio at 7 ± 3 DIM compared with PLC cows (ASA = 0.062 ± 0.002; MEL = 0.064 ± 0.002; PLC = 0.056 ± 0.002). Regardless of treatment, there was an interaction between parity and day. Parous cows had higher type 1/type 2 ratios compared with nulliparous cows at 14 ± 3 d before calving and at 7 ± 3, 14 ± 3, and 21 ± 3 d after calving. Furthermore, there was a positive correlation between D2Dx scores at 14 ± 3 DIM and average daily milk yield in the first 60 DIM. These results suggest that prepartum anti-inflammatory therapies may cause an increased shift in type 1 immunity around calving. Similarly, parous cows may have an increased shift in type 1 immunity after calving. Interestingly, higher type 1/type 2 ratios may be associated with higher milk yields in the first 60 DIM. Larger studies are needed to identify associations between the D2Dx immunity test and cow health and performance, as well as to assess the applicability of these types of tests in a conventional farm setting.

Evaluation of trait preferences and effect of parity, season and lactation stage on production performance of indigenous dairy cow in kaffa zone, southwest Ethiopia

The current research focused on the effects of parity, season, and lactation stage on the milk yield of indigenous dairy cows in selected districts of the Kaffa Zone of southern Ethiopia. The districts of Gesha and Chena were purposefully chosen. The study design for the 384 household surveys was a cross-sectional survey with a simple random sample approach as the sampling method. Following the survey, 192 lactating cows were chosen for a monitored investigation to track nighttime and morning milk supply. In addition to key informants and focus group discussions, primary and secondary data were obtained via a semi-structured questionnaire, interview, and field observation. The most favored features functioning as selection criteria were those favored for production, reproduction, physical appearance, physiological function, and temperament, in that order. Evening milk yield (EMY), mornning milk yield (MMY), daily milk yield (DMY), lactation length (LL) and lactation milk yield (LMY) were 0.91 ± 0.033 L, 1.22 ± 0.037 L, 2.125 ± 0.07 L, 6.36 ± 0.116 months, and 427.10 ± 20.678 L, respectively, with significant difference (p < 0.01) amongst districts, parity, and season. However, there was no significant variation between studies in EMY, MMY and DMY. Significantly higher values of production performances were recorded for interaction among districts, parity, and season. The study also revealed that interaction between district (Gesha) and parity (third), which were signficantlly higher for EMY, MME, DMY, LL, and LMY 1.50 L, 2.00 L, 3.50 L, 8.10 months, and 850.50 L, respectively. The same trend also observed for interaction among district (Gesha), season (wet), and parity (third), which were obtained to be highly significant values of EMY, MMY, DMY, LL, and LMY were 1.35 L, 1.75 L, 3.10 L, 7.65 months, and 716.80 L, respectively. The study region has a large population of indigenous dairy cows and produces higher yields than the national average. However, it falls short of the worldwide production benchmarks, and the trait preferences used as a selection criterion were based on the farmers' indigenous knowledge. Measures to enhance production abilities must be incorporated and selection criteria must be modernized.

Associations of production characteristics with the on-farm presence of Fasciola hepatica in dairy cows vary across production levels and indicate differences between breeds

Fasciola hepatica is one of the economically most important endoparasites in cattle production. The aim of the present work was to evaluate the relevance of production level on the associations of on-farm presence of F. hepatica with farm-level milk yield, milk fat, and milk protein in Holstein cows, a specialised dairy breed, and in Simmental cows, a dual purpose breed. Furthermore, we investigated whether differential associations were present depending on breed. Data from 560 dairy farms across Germany housing 93,672 cows were analysed. The presence of F. hepatica antibodies was determined via ELISA on bulk tank milk samples. Quantile regression was applied to model the median difference in milk yield, milk fat, and milk protein depending on the interaction of breed and fluke occurrence. Whereas a reduction in milk yield (-1,206 kg, p &lt; 0.001), milk fat (-22.9 kg, p = 0.001), and milk protein (-41.6 kg, p &lt;0.001) was evident on F. hepatica positive German Holstein farms, only milk fat (-33.8 kg, p = 0.01) and milk protein (-22.6 kg, p = 0.03) were affected on F. hepatica positive German Simmental farms. Subsequently, production traits were modelled within each of the two breeds for low, medium, and high producing farms in the presence of F. hepatica antibodies and of confounders. On Holstein farms, the presence of F. hepatica seropositivity was associated with lower production, while on German Simmental farms such an association was less evident. This work demonstrates that production level is relevant when assessing the associations between the exposure to F. hepatica with production characteristics. Moreover, both models indicate a breed dependence. This could point towards a differential F. hepatica resilience of specialised dairy breeds in comparison with dual purpose breeds.

Application of the BLUP Animal Model method in assessing the breeding value of the breeding stock of Ayrshire cattle

The aim of the study is to assess the breeding value of the breeding stock of Ayrshire cattle from 13 breeding farms in various regions of the Russian Federation using the BLUP Animal Model method.Materials and methods. The analyzed sample included data on 14,450 cows with a first calving date of 1987 – 2021, which were analyzed for identification errors and discrepancies in the dates of birth of parents and offspring. The forecast of the breeding value of cows based on milk productivity traits for 1 lactation was made using the best linear unbiased forecast method BLUP Animal Model using the RStudio program.Results. The dynamics of milk yield EBV values during the studied time period with different numbers of first calving cows was studied. EBV estimates varied not only depending on the level of absolute milk yield of first-calving cows, but also under the influence of factors such as reproduction, the number of herds being assessed, as well as management, by which herds differed.Conclusion. The assessment of breeding value using the BLUP AM method made it possible to reliably evaluate the studied array of animals of the Ayrshire breed breeding stock on farms in the Russian Federation. The best and worst producers in terms of milk yield were identified, taking into account the effects of various factors.

Cladodes of Opuntia ficus-indica (L.) as a source of bioactive compounds in dairy products

Recently, the interest in improving livestock product nutraceutical profiles through sustainable feeding systems has increased. In this context, the overall quality and nutraceutical profiles were examined in dairy products obtained from 16 lactating Cinisara cows given an integrated feed in dry season with Opuntia ficus-indica cladodes. Two homogeneous groups of cows (milk yield: 6.3 ± 1.5 kg; body weight: 213 ± 55 kg) were fed with 2 different diets (CON: pasture and wheat bran; OFI: pasture, wheat bran, and cladodes), according to a 2 × 2 Latin square design. The bulk milk produced during the study was used to make Caciotta cheese and was analyzed at 0, 15, and 30 storage days. Milk and cheese samples were analyzed for chemical, physical, and microbiological traits. The nutraceutical and sensorial profiles, as well as the antioxidant capacity, were also determined in the final products. For milk, the urea content in individual samples was reduced in OFI but not in CON. In the cheese, integration of cladodes did not influence the starter cultures development with 2 strains of Streptococcus thermophilus, but it caused a higher content of polyphenols and a consequent greater antioxidant capacity and a change in the fatty acids profile. In particular, the caprylic, capric, lauric, myristic, and palmitic fatty acids were higher, as were the petroselinic, vaccenic, rumenic, and α-linolenic fatty acids. In contrast, the oleic and the γ-linolenic fatty acids were lower for OFI. The cheese from the OFI group showed better overall acceptability, and a higher yellow color, odor intensity, and butter flavor. The multivariate analysis well distinguished the cheeses belonging to the 2 groups. Further investigations should be conducted to formulate well-balanced diets that include cladodes for Cinisara lactating cows, but also to determine the content of other important bioactive compounds in fresh and treated cladodes, as well as their effects on animal welfare and production.

Moringa oleifera leaf meal supplementation improves nutrient digestibility, milk yield, and reproductive performances in dairy cows during early lactation.

The study aimed to evaluate the effects of Moringa oleifera leaf meal (MOLM) supplementation on nutrient utilization, milk yield, and reproductive performance of early lactating Sahiwal cows. Control cows (GC) received a basal diet, while the treatment cows (GM) were supplemented with concentrate comprising 12% MOLM. Ovarian activity and uterine involution were monitored by trans-rectal ultrasonography on the 21st, 28th, 35th, and 42nd days postpartum. The result indicated that MOLM-supplemented cows required fewer days (P ≤ 0.05) to complete uterine involution. As lactation progresses, there was a significant reduction (P ≤ 0.05) in the diameter of the cervix and uterine horns in GM than GC. There was a significant increase in the number of follicles on the 21st day and average milk yield in GM than GC. The incidence of endometritis and cystic ovarian disease was less in MOLM supplemented group. The use of MOLM in the diet reduced the total cost per cow per successful service. It is concluded that MOLM can be safely included at 12% in the diet of early lactating cows to modulate the reproductive performances of dairy cows. Dairy farmers can use moringa leaf meal to feed their dairy cows, which is cheaper and improves production and reproduction performance.

205 Level of Supplemental Fat in the Diet of Gestating Beef Cows: Effects on Cow and Calf Performance

Abstract This study evaluated the effects of feeding a canola seed-based (7.2% ether extract) pellet to gestating cows on cow performance, reproductive efficiency, milk yield and composition, and calf birth weight. Seventy-two pregnant, multiparous cows were allocated to 12 pens in a completely randomized block design. Body weight (BW; 605 ± 35 kg) was utilized as the blocking criteria. Diets were formulated to be isonitrogenous (CP: 8.20 ± 0.24% and 9.07 ± 0.05% second and third trimesters, respectively) and isocaloric (TDN: 58.29 ± 0.24% and 60.50 ± 0.04% second and third trimesters, respectively), and to meet NASEM (2016) nutrient requirements for pregnant beef cattle. Pens were randomly assigned to three replicated (n = 4) dietary treatments: 0 (CON), 150 (LOW), and 300 (HIGH) g of fat/d (DM basis). Dietary treatments were fed from 148 ± 8 d prepartum until at least 50% of all cows had calved, then switched to a common lactation diet. Body condition score (BCS), BW and subcutaneous fat thickness were measured at the start (SOT) and end of trial (EOT), and at 21 and 42 d postpartum. Orthogonal contrasts were used to assess linear and quadratic relationships between fat inclusion and dependent variables. At SOT, there were no differences (P ≥ 0.73) in conceptus corrected BW (597 ± 34 kg) or (P ≥ 0.13) BCS (2.85 ± 0.12, Canadian System: 1 to 5). After 84 d on trial (64 ± 8 d prepartum), conceptus corrected average daily gain (ADG) increased linearly (P = 0.04) as fat inclusion increased. After 151 d of supplementation (EOT), conceptus corrected ADG and subcutaneous fat thickness did not differ (P ≥ 0.71 and 0.63, respectively). BCS change from SOT to EOT increased, while EOT to 21 d postpartum decreased quadratically as fat inclusion increased (P = 0.02 and 0.01, respectively). Female calf birth weight decreased quadratically (P = 0.01) as fat inclusion increased, but there was no effect (P ≥ 0.75) on male calf birth weight. As fat inclusion increased, lactose concentration in milk decreased linearly (P = 0.04). As days in milk (DIM) increased, milk protein, total solids, and milk energy yield decreased (P ≤ 0.05). Milk urea-N tended to increase (P = 0.07), while 12 h milk yield (P = 0.05) tended to decrease as DIM increased. Milk fat and energy were not affected by fat inclusion, day, or the interaction between fat inclusion and day (P ≥ 0.16). There was a quadratic tendency for fat inclusion to affect pregnancy rate (P = 0.09), being maximized on LOW treatment. These results suggest that increasing fat inclusion during mid-to-late gestation tended to improve cow reproductive efficiency. Further investigation is required to determine the optimal level of fat inclusion from canola seed.

PSII-19 A Satellite-Based Decision-Support Tool to Optimize Profitability and Environmental Stewardship of Cow-Calf Operations

Abstract Management strategies implemented in cow-calf operations are essential to capitalize on heavier feeder calves, but field data collection can restrict their practical application. A computer program to optimize weaning weight, profitability, and environmental sustainability of grazing cow-calf operations was developed by combining an existing mechanistic nutrition model with pasture biomass estimated using satellite images. Data from the Texas A&amp;M University McGregor Research Center was used as a testbed for the computer model. Pasture forage data from 2016 to 2022 was collected via satellite imagery, and the predicted pasture biomass was adjusted based on third-party algorithms (Sigfarm Intelligence LLC). Nutrient requirements were estimated using the Ruminant Nutrition System (RNS), and a constant pasture nutritive value was obtained. The potential dry matter intake (DMI) was estimated from the initial herd size (input). Actual average weaning weight was used to predict cow milk yield and total metabolizable energy requirements, which was used to estimate the required DMI (DMR). The actual forage allowance was correlated to DMR, and we simulated the forage allowance to support increased DMI and, consequently, increased milk yield to achieve a targeted average weaning weight. Based on Intergovernmental Panel on Climate Change (IPCC) methodology, environmental impact was evaluated from greenhouse gas emission estimates. Our simulations demonstrated that increasing the target weaning weight of a smaller herd with fewer mature cows (757 cows) would produce heavier calves, resulting in a 6% decrease in calf gain per pasture area. Nevertheless, the net income increased in scenarios with heavier weaned calves. The enhanced productivity with heavier weaned calves and fewer cows resulted in a lower carbon emission per kg of produced weaned calves. Based on our simulation, a herd size between 757 and 812 mature cows yielding calves weaned between 280 and 300 kg would be an optimal management strategy for the studied operation. This computer model provides the fundamental framework for a decision-support tool for producers to optimize their cow-calf operations while producing ideal weaned calves for feedlot operations.

The effect of the silvopastoral system on milk production and reproductive performance of dairy cows and its contribution to adaptation to a changing climate in the drylands of Benin (West-Africa)

Knowledge about dairy cows raised in small-scale agroforestry systems in dryland areas is of paramount importance to inform policy and decision making in the dairy production sector in the current context of climate change. The aim of this study was to evaluate the effect of integrated farming systems on daily milk yield and demographic traits of dairy cows in drylands. A study conducted on 447 dairy cows was carried out to compare their milk yield and demographic parameters under different small-scale agroforestry systems in drylands of Benin: traditional silvopasture (TSS); Improved silvopasture (ISS); Small Integrated Agrosilvopasture (SIAS) and Large Integrated Agrosilvopasture (LIAS). The type of cattle farms had a significant effect (p &amp;lt; 0.05) on daily milk yield and demographic traits. Dairy cattle from ISS farms had the highest daily milk yield regardless of the type of dairy cow breed. Demographic traits of herds were significantly (p &amp;lt; 0.05) influenced by the type of dairy cattle farms. The proportion of lactating cows was higher (p &amp;lt; 0.05) in herds of ISS (48.4%) followed by those in TSS and LIAS (36.1 and 25.0% respectively) while SIAS was the lowest in (14.4%). The pre-weaning mortality rate was higher (p &amp;lt; 0.05) in TSS and LIAS farms (18.3 and 17.6 % respectively) compared to SIAS and ISS farms (5.20 and 4.60 % respectively). The fertility rate was higher (p &amp;lt; 0.05) in ISS and SIAS farms (92.3 and 89.6% respectively) compared to TSS and LIAS farms (68.3 and 74.2% respectively). The weaning productivity was higher (p &amp;lt; 0.05) in ISS and SIAS (88.6 and 85.8 % respectively) than in TSS and LIAS farms (66.1 and 67.6 % respectively). This study showed that ISS farms are characterized by higher milk yield and demographic parameters. ISS systems can then be promoted in smallholder cattle farming to improve milk production and reproductive performance of dairy cows in drylands.

Relationship of body condition and milk parameters during lactation in Simmental cows in Bavaria, Germany.

In dairy cows the body condition forms a reflection of the energy reserves of the organism. Health, welfare and productivity of dairy cows are strongly associated with changes in body condition. As lactation puts substantial demands on the metabolism of dairy cows, farm management aims at avoiding either a deficient body condition or a substantial loss of body condition within a short period of time. A body condition higher or lower than recommended (over- and underconditioning in the following) compromises dairy cow productivity. While the body condition of Holstein Friesian cows has been thoroughly explored, few is known about the consequences of deviations from a target body condition for health and productivity of cows from other breeds. This study explores the percentage of over- and underconditioned cows at different days post partum [dpp] and their association with production parameters i.e., milk yield, milk fat and milk protein content of Simmental cows on Bavarian farms, categorized by parity (primi- or multiparous). Our study displays that in Simmental cows, overconditioning is more prevalent than underconditioning. While the middle of lactation (dpp = 100-199) resulted in higher percentage of overconditioning, the dry period (dpp = < 0 & > 299) indicated a higher percentage of underconditioned cows. The dry period and the middle of lactation are therefore the most challenging lactation stages for Simmental cows. We found milk protein content to have the strongest association with over- and underconditioning in Simmental cows. The probability of overconditioning was higher with higher milk protein content for every lactation stage and the probability of underconditioning was lower with higher milk protein content in every lactation stage. This study provides a theoretical basis for potential improvements in stockbreeding, which, if implemented, could improve not only the milk yield of Simmental dairy cows, but also their health and welfare.

Genetic aspects of Wood's lactation curve parameters in Jersey crossbred cattle using Bayesian approach.

The study was undertaken to estimate the genetic parameters of lactation curve parameters of Wood's function in Jersey crossbred cattle using the Bayesian approach. Data on 33,906 fortnightly test day milk yields of 1,718 lactation records of Jersey crossbred cows, maintained at the ICAR-National Dairy Research Institute in West Bengal, were collected over a period of 40 years. The lactation curve parameters including 'a' (initial milk yield after calving), 'b' (ascending slope up to peak yield) and 'c' (descending slope after peak yield) and lactation curve traits, peak yield (ymax), time of peak yield (tmax) and persistency of milk yield (P) of individual cow for each lactation were estimated using the incomplete gamma function (Wood's model) by fitting the Gauss-Newton algorithm as an iteration method using PROC NLIN procedure of SAS 9.3. Variance components and genetic parameters of lactation curve parameters/traits were estimated by a repeatability animal model using the Bayesian approach. Estimates of heritabilities were found to be 0.18 ± 0.05, 0.09 ± 0.03 and 0.11 ± 0.04 for parameters 'a', 'b' and 'c', respectively and 0.24 ± 0.05, 0.12 ± 0.04, and 0.15 ± 0.05 for ymax, tmax and P, respectively. Repeatability estimates were 0.31 ± 0.03, 0.21 ± 0.04 and 0.30 ± 0.04 for parameters 'a', 'b' and 'c' respectively and 0.39 ± 0.03, 0.24 ± 0.03 and 0.37 ± 0.03 for ymax, tmax and p, respectively. Genetic correlations among lactation curve parameters/traits ranged from -0.75 to 0.95. Existence of genetic correlations among lactation curve parameters/traits indicated substantial genetic and physiological relationships among lactation curve parameters/traits of Jersey crossbred cattle.

Bovine CD14 Gene Polymorphism and its Association with Milk Yield, Milk Constituents and Somatic Cell Count in Holstein Friesian Crossbred and Gir Cows

Bovine CD14 Gene Polymorphism and its Association with Milk Yield, Milk Constituents and Somatic Cell Count in Holstein Friesian Crossbred and Gir Cows

The variation in the beta-casein genotypes and its effect on milk yield and genomic values in Holstein-Friesian cows

The A2 milk marker is gaining popularity worldwide; thus, many farms plan to convert their dairy cattle herds to the A2A2 genotype. Variation in beta-casein genotypes needs to be monitored in large dairy cattle populations. Therefore we aimed to evaluate the genotypic distributions, population genetics, and diversity parameters in Holstein-Friesian cows. A total of 1200 cattle were genotyped using the Affymetrix® Axiom® array system. We performed an association analysis regarding the CSN2 genotypes and phenotypic traits, including lactation and test-day milk yield. We next evaluated the effects of the genotypes considering the genetic merit of the animals. Animals were grouped based on their PTAs for milk production, fat, protein, and daughter pregnancy rate. Thus, we tested the genotype × genetic merit interaction for significance. The A2 allele frequency is remarkably high (0.68), and the heterozygous genotype is predominant (46.25%). The marker showed intermediate variability and diversity levels, indicating a considerable frequency of the A1A1 genotype (9.33%) remains in the population. ANOVA results showed no significant association between the CSN2 genotypes and milk yield traits. A similar finding is valid for the genotype × genetic merit regarding the genomic test results. The data presented here may be helpful for further investigations and applications on A2 milk production.

Genetic aspects of immunoglobulins and cyclophilin A in milk as potential indicators of mastitis resistance in Holstein cows

Mastitis is one of the most frequent and costly diseases affecting dairy cattle. Natural antibodies (immunoglobulins) and cyclophilin A (CyPA), the most abundant member of the family of peptidyl prolyl cis/trans isomerases, in milk may serve as indicators of mastitis resistance in dairy cattle. However, genetic information for CyPA is not available, and knowledge on the genetic and nongenetic relationships between these immune-related traits and somatic cell score (SCS) and milk yield in dairy cattle is sparse. Therefore, we aimed to comprehensively evaluate whether immune-related traits consisting of 5 Ig classes (IgG, IgG1, IgG2, IgA, and IgM) and CyPA in the test-day milk of Holstein cows can be used as genetic indicators of mastitis resistance by evaluating the genetic and nongenetic relationships with SCS in milk. The nongenetic factors affecting immune-related traits and the effects of these traits on SCS were evaluated. Furthermore, the genetic parameters of immune-related traits according to health status and genetic relationships under different SCS environments were estimated. All immune-related traits were significantly associated with SCS and directly proportional. Additionally, evaluation using a classification tree revealed that IgA, IgG2, and IgG were associated with SCS levels. Genetic factor analyses indicated that heritability estimates were low for CyPA (0.08) but moderate for IgG (0.37), IgA (0.44), and IgM (0.44), with positive genetic correlations among Ig (0.25-0.96). We also evaluated the differences in milk yield and SCS of cows between the low and high groups according to their sires' estimated breeding value for immune-related traits. In the high group, IgA had a significantly lower SCS in milk at 7 to 30 d compared with that in the low group. Furthermore, the Ig in milk had high positive genetic correlations between healthy and infected conditions (0.82-0.99), suggesting that Ig in milk under healthy conditions could interact with those under infected conditions, owing to the genetic ability based on the level of Ig in milk. Thus, Ig in milk are potential indicators for the genetic selection of mastitis resistance. However, because only the relationship between immune-related traits and SCS was investigated in this study, further study on the relationship between clinical mastitis and Ig in milk is needed before Ig can be used as an indicator of mastitis resistance.

Effects of oyster glycogen intramammary challenge on primiparous cow milk somatic cell counts, milk yields, and milk composition

Mastitis is a common and costly disease in the dairy industry that reduces milk production in affected mammary glands. The local mechanisms that result in reduced milk production of affected mammary glands are incompletely understood; elucidation of these mechanisms is dependent on the use of hypothesis testing studies, but few experimental models exist. The objective of this study was to develop a mastitis challenge model, using a split udder design, to reduce milk yields by approximately 15% in udder halves challenged with oyster glycogen, a known inducer of leukocyte recruitment, relative to udder halves treated with saline. Four primiparous Holstein cows in mid lactation were used. One udder half of each cow was randomly selected and challenged with oyster glycogen (OYGLN), and the opposite udder half was treated with saline (SAL). Milk yields and components were measured at each milking (3×/d) for 3 d postchallenge. No signs of clinical mastitis were observed. Milk somatic cell scores, yields, and components were similar between OYGLN and SAL udder halves at time of challenge. Milk somatic cell scores markedly increased in OYGLN halves postchallenge and were greater than SAL halves for the duration of the trial. Lactose concentrations of OYGLN udder halves were transiently lower than in SAL udder halves, but protein concentrations were greater at 2 milkings postchallenge in OYGLN halves. Milk yields and energy-corrected milk yields did not differ between OYGLN and SAL udder halves overall, nor at any postchallenge milking. A single intramammary challenge of oyster glycogen was unsuccessful in eliciting a disparity in milk yields between challenged and saline control udder halves despite the marked leukocyte infiltration observed in the former. These results indicate an incomplete understanding of how milk yields are reduced in mammary glands affected by subclinical mastitis and that transient somatic cell recruitment and infiltration alone do not directly reduce milk yields during subclinical mastitis.

Performances of cattle and goats in some selected areas of Gaibandha district in Bangladesh

The survey was conducted to represent the livestock production scenario and to know the performances of cattle and goats in few selected rural areas of Gaibandha district. The data on productive and reproductive performances of cattle and goats were collected from 102 household within four selected village under Gobindaganj Upazila of Gaibandha district with a pretested survey questionnaire. The collected data were compiled, tabulated and analyzed by student t test. In the study area, about 59% were indigenous cattle and 41% were crossbred cattle. A total of 113 goats were found in the study area of which 82% belongs to Black Bengal goat and the remaining 18% belongs Jamunapari goat. All the livestock (100%) were managed intensively during the spring and rainy seasons. Similarly, almost all livestock (100%) are confined in shed at night, and 45.9% and 54.09% of the livestock population are confined in shed and paddock at day time, respectively. Artificial insemination (AI) is the preferred breeding method for cattle, whereas goats primarily rely on natural mating. Milk yield and lactation period of cow, and mature body weight of both male and female were significantly (P&lt;0.05) higher in crossbred than indigenous cattle. Similarly, age at first kidding, lactation period and kidding interval of does, and mature body weight of buck and does were significantly higher in Jamunapari goats than Black Bengal goats. However, the conception rate and number of kids per kidding were higher in Black Bengal goats than Jamunapari goats. In conclusion, from our results, crossbred cattle and Jamunapari goats are performing better in rural conditions, whereas Black Bengal goats are efficient in producing more offspring at a given time. Bangladesh Journal of Animal Science 52 (3): 78-84.

Characteristics of the families of the herd of the Sychevka breed by productive and genetic indicators

An analysis of the genetic structure using marker alleles of the EAB locus and an assessment of the productive qualities of the families of cows of the Sychevka breed of the pedigree farm KP "Rybkovskoe" of the Smolensk region is presented. In the genotypes of representatives of families with a frequency of more than 5%, there are EAB alleles of the Holstein breed: Y1A`1, G2Y2E`1Q`, O2A`2J`2K`O`, B2O1, and the Sychevka breed: O1I`Q`, b, O1Y2E`3G`G``, which indicates the presence of hereditary material of both breeds. The average milk yield for maximum lactation in cows of the families was 5624kg of milk, with a fat content of 3.91%, protein 3.28%. In the best cows of the families, milk productivity reached 9651kg of milk, 3.71% fat, 3.28% protein for maximum lactation. Thirty percent of descendants from the families of Laskovaya 7114 and Kladi 8080 have a milk yield of over 6000 kg, with a fat content in milk of 3.82% and higher, and protein - over 3.35%. Milk yield in cows, on average in the group by the third lactation compared to the first increases by 970 kg of milk or 22%, which is largely due to the milking of animals in the process of their use. The greatest increase (41%) in milk yield to full-age lactation is observed in animals with the alleles E`3G`G`` (+1681kg) and B1G3O1T1A`1B`E`3F`2Q` (+1706kg). Cows with the EAB allele B1G2O1 are different by an increased (by 40%) period of productive use, and, as a result, lifetime milk yield, they are 42% higher than the average for families. Cows with the marker allele P1QA`1J`2E`1I` have lifetime milk yield indicators 69.5% higher than the average for families.

Effects of rumen-protective γ-aminobutyric acid additive on lactation performance and serum biochemistry in heat-stressed cows.

In the context of global warming, heat stress has become one of the major stress factors limiting dairy cattle production. Although many methods have been explored to help cows mitigate the negative effects of heat stress during the hot summer months, maintaining the performance of high-yielding cows under heat stress is still a great challenge. The aim of this trial was to investigate the effect of RP-GABA in the diet on milk yield, milk composition and serum biochemical parameters in heat-stressed cows. Twenty Chinese Holstein cows in early lactation (51.00 ± 4.92 kg milk/d, 71 ± 10.94 d in milk and 2.68 ± 0.73 parities) were included in this experiment and randomly divided into four groups (n = 5/group). The four experimental groups consisted of one control group (0 g RP-GABA/d) and three treatment groups, given 5, 7.5 and 10 g RP-GABA/d of dry matter (DM) per cow, respectively. The results showed that supplementing high-yielding cows with 10 g/d of RP-GABA improved milk protein production but had no effect on the improvement of other production performance, the alleviation of heat stress in cows, or the improvement of immune function and antioxidant capacity. Ultimately, we conclude that the supplementation of 10 g/d RP-GABA to heat-stressed, high-yielding dairy cows can provide a degree of performance enhancement. Furthermore, our study provides some reference for nutritional improvement measures for summer heat stress in dairy cows, especially high-yielding cows.