Milk Loss Research Articles

Estimating milk loss based on somatic cell count at the cow and herd level

There is a direct relationship between elevated somatic cell count (SCC) in an individual cow milk production and milk loss. This relationship has been used at the herd level to estimate an overall herd milk loss due to subclinical mastitis and to use recovery of this lost milk as a financial benefit to cover the cost of intervention strategies to improve milk quality. The objective of this study was to estimate the recoverable milk revenue on a per cow basis for herds moving from one herd average SCC level to a newer, lower level. Test-day records from 1,005,697 dairy cows in 3,741 herds between 2009 to 2019 were used. Milk yield loss for each cow in each herd on test day was estimated using a mixed effects regression equation, and then summed to estimated total herd milk loss. These herd average daily milk loss estimates were then related to the bulk tank SCC, and the distribution of underlying individual cow SCC were examined. The distributions in daily herd milk loss for various bulk tank SCC values were generated, and estimates of recoverable milk loss were generated to simulate a herd moving from their current bulk tank SCC to a new lower level. The results indicate that estimates of total herd milk yield loss vary with the distribution of cow-level SCC and parity within the herd, so it is imperative that milk loss be calculated on a per cow basis. Further, the recoverable milk loss estimates based on moving to a lower bulk tank SCC where milk loss is still occurring was relatively small compared with the traditional assumption that all milk loss would be recovered, and less than most herd owners and advisors would expect.

Молочная продуктивность и воспроизводительные показатели коров черно-пестрой породы в зависимости от технологии получения молока

Abstract. Milking cows is the final stage, which determines the effectiveness of milk production with all other issues resolved. The number of dairy farms equipped with modern milking machines is growing in the republic. Simultaneously with the increase in milk productivity of cows, the task is to use the least labor-intensive and energy-intensive technologies for milk production. At the same time, the health and tranquility of cows is a prerequisite for this, it is necessary to use modern technologies. The purpose is to study the impact of milking technology on the level of milk productivity, milk quality and reproductive indicators of cows. The object of the study is cows of black-and-pesky breed in the leading tribal farms of the Vavozhskiy district of the Udmurt Republic – collective farm (APC) named after Michurin and APC collective farm “Kolos”. Methods. Three groups of cows were formed using the pair-analog method: 1st group – loose-box keeping of cows using a robotic milking system, 2nd – loose-box keeping using milking machines “Evroparallel”, 3rd – loose-box keeping using the technology of milking cows through the milking parlor “Кarusel”. Results. Thus, in case of careless-box content and use of robotic milking plant, cows of black and pesky breeds outnumbered cows, which were fed using “Evroparallel” plant and milking technology with the help of milking hall “Кarusel” on all indicators of dairy productivity investigated by us (except for content of mass fraction of protein in milk) and reproduction qualities. Scientific novelty. Milking machines of outdated designs do not quite meet the physiological state of the animals, which leads to the loss of milk, premature start of cows and the incidence of mastitis. Thus, in the Udmurt Republic, new farms and complexes are being built, which are equipped with modern automated milking equipment, which excludes direct human participation in the process of obtaining milk, thereby increasing the quality and quantity of milk.

Chlorine Solutions for a Safe Method of Decontamination of Breast Pump Milk Collection Kits Before and After the Coronavirus Disease 2019 Pandemic.

To promote breast feeding and breast pumping is essential for the most vulnerable infants even if the current coronavirus disease 2019 (COVID-19) pandemic sanitary crisis imposes more stringent hygienic measures. As recommended by the Centers for Disease Control and Prevention, World Health Organization, and Milk Bank Association, “after each pumping session, all pump part that come into contact with breast milk should be appropriately disinfected.” The present study proposed different methods than can be used and focus on the safety analysis of chlorine solution (CS) in terms of residual hypochlorous acid (HCA) and total trihalomethanes (THM). We also performed an efficacy testing of the CS approach to decontaminate the devices used to collect the milk (breast pumps and bottles). The bacteriologic results of 1,982 breast pump milk samples collected in three different settings showed a major decrease of the microbial contamination using either sterile device or decontamination with CS compared to a simple soap washing. The main messages from our study are to propose a guideline for the safe use of CS and to define situations when breast pump decontamination might be necessary: vulnerable babies for which sterile device is recommended; special circumstances, for example the current COVID-19 pandemic; special situations, for example women living in precarious conditions; or women pumping their milk at work but that would have low or no access to boiled water. Overall, cold decontamination reduced losses of milk for bacteriological reasons in human milk banks and may also be interesting to prevent horizontal contamination by virus like COVID-19.

Waste Reduction by Improved Quality Control And Hadzad Analysis And Critical Control Point (HACCP) Implementation: A Case Study From Edfina Company For Presrved Foods, Alexandria, Egypt

Abstract Under the Under the project Support for Environmental Assessment and Management (SEAM), This project is being implemented by Reduction of Milk Losses at Miser Company for Dairy and Food, Mansoura, Egypt. It was implemented under the National Industrial Pollution Prevention Programmers (NIPPP). NIPPP focuses on the introduction and promotion of low-cost improvement measures, which can be easily and quickly implemented by factories. It also emphasizes the importance of economic benefits of any such intervention, particularly those with short pay-back periods. A summary of how these improvements were identified and the underlying problems solved, follows. Waste minimization through improved quality control procedures was implemented at Edfina Company for Preserved Foods, Alexandria, Egypt. A number of interventions costing LE 65,200 (Egyptian Pound) have yielded annual savings of LE 382,622. Quality control training and the implementation of Hazard Analysis and Critical Control Point (HACCP) system will lead to improved product quality and further savings. Although it is difficult to quantify at this stage further savings of LE 550,000 could be expected in the short term.

Immunization with a novel recombinant protein (YidR) reduced the risk of clinical mastitis caused by Klebsiella spp. and decreased milk losses and culling risk after Escherichia coli infections

The primary objective of this study was to evaluate the protective efficacy of a novel recombinant subunit vaccine containing the protein YidR (rYidR) against clinical mastitis (CM) caused by Klebsiella spp. and Escherichia coli. Given that E. coli infection is known to cause metritis, we also evaluated the effect of rYidR vaccination on the incidence of metritis and conception at the first artificial insemination. Retained placenta and abortion incidence, milk production and composition, and serological responses to specific antigens were also evaluated. In total, 3,107 cows were blocked by parity and randomly allocated into 1 of 3 treatment groups: experimental recombinant subunit vaccine containing the YidR protein (rYidR); commercial vaccine composed of Klebsiella pneumoniae siderophore receptors and porin protein (Kleb-SRP; KlebVax, Epitopix, Willmar, MN); and sterile water adjuvanted with aluminum hydroxide (20%; placebo). Vaccinations were performed at the dry-off for cows, and at 223 ± 3 d of pregnancy for pre-fresh heifers. A second administration was given at 21 ± 3 d after the first injection. Vaccination with rYidR significantly reduced the incidence of CM caused by Klebsiella spp. (3.2%) when compared with the placebo (5.1%) group. No difference was observed on risk of Klebsiella CM between Kleb-SRP (5.9%) and placebo groups. Cows in the rYidR group that experienced E. coli CM had a lower risk of death or culling (12.5%) compared with the Kleb-SRP (27.6%) and placebo groups (27.8%). Furthermore, among cows that developed E. coli CM, rYidR-immunized cows produced more milk than did cows in the placebo and Kleb-SRP groups. Regardless of CM occurrence, rYidR-immunized cows tended to have higher milk production up to the eighth month of lactation than cows in the other groups. No significant effect of treatment was observed on the overall incidence of abortion and metritis; however, the risk of retained placenta tended to be lower for the rYidR group (4.7%) compared with the placebo group (6.7%). In addition, primiparous cows in the rYidR group had the highest conception risk at the first artificial insemination (48.3%) compared with the placebo (39.5%) group, and no significant difference was observed when the Kleb-SRP (40.1%) group was compared with the placebo group. Generally, higher antibody serum titers (IgM and IgG) were observed for the immunized groups compared with the placebo. In conclusion, the rYidR vaccine reduced the risk of CM caused by Klebsiella spp. and the mortality or culling of cows with E. coli infections. Other benefits of the novel vaccine include maintenance of milk production after CM caused by E. coli, and higher conception risk at the first service in primiparous cows compared with cows in the placebo and Kleb-SRP groups.

The impact of somatic cell count on milk yield and composition

The impact of somatic cell count on milk yield and composition

Measurement of Food Losses in a Hungarian Dairy Processing Plant.

The phenomenon of food waste and food loss at any stage of the supply chain is significant in developed economies. The purpose of this article is to highlight the areas of milk processing where milk loss occurs, and, after quantifying the data obtained, reveal the extent of the losses. To achieve the goals, we conducted on-site visits to one of Hungary’s milk processors. The methodology is based on the Food Loss and Waste (FLW) standard, accordingly we determined the extent of milk loss at the company level, supplemented with loss values by each dairy product. During the analyzed processing stages (receiving of raw milk, skimming, pasteurization, Extended Shelf-Life (ESL) milk, cheese milk, sour cream, yoghurt, and kefir) 1203.4–1406.8 L of raw material per day can be accounted as losses, which makes up 0.9–1% of daily production. A Milk Production-Milk Losses (MPML) model was created where six factors (technology and automation, design of the plant aspects, quantity of orders, expertise of employees, number of product variants, optimal storage capacity) were methodized that significantly influence the rate of milk losses over different time periods. Our paper highlights how areas of the production stage can be developed to decrease milk loss.

THE INFLUENCE OF THE AGENDA ON THE PRODUCTIVITY OF COWS OF DIFFERENT LACTATIONS UNDER DIFFERENT KEEPING REGIMES

It was found that during lactation the milking of cows in the experimental groups at the constant regime were at the level of 4639 kg of milk, which is more than at the variable regime by 159.8 kg or 3.57%. As a result, the cost of feed in the variable mode of the day per 1 kg of milk was 1.38 feed units, and at constant - 1.10 feed units, which is less than 0.28 feed units or 20.3%. The constant daily routine reduced labor costs in milk production by 9.7%, and by 1 quintal of milk - 34.2%.
 It is presented that it is inexpedient to violate the daily routine, which leads to the loss of marketable milk by more than 3.6%.

New Advance study reveals hidden losses to BVD in milking herds

Discussing BVD with clients in terms of milk losses and economic impact is not always easy. The new Advance study aimed to contextualise losses related to unseen BVD in a milking herd, which is often one of the most difficult conversations to have with clients who believe that testing and screening alone will suffice. A milk loss and potential additional income calculator has been developed with the data from the study.

Effect of Land Degradation on Livelihood

Land degradation is a process in which the value of the biophysical environment is affected by a combination of human-induced processes acting upon the land. It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable. Land degradation: A decline in the quality or performance of land. Or erosion of the earth land surface by water, wind, or ice. Land degradation affects people and ecosystems throughout the planet and is both affected by climate change and contributes to it. The prolonged effect of land degradation has resulted in erratic rainfall causing severe droughts at irregular intervals, and these droughts threaten the lives and livelihoods of millions of people. According to the FAO, the world's cultivated soils - meaning soils that have been rearranged - have lost between 25% and 75 % of their original carbon stock, which has been released into the atmosphere in the form of carbon dioxide. The simulated results of costs of loss of milk, meat, and costs associated with weight loss of animals not slaughtered or sold associated with land degradation in grazing biomass.

Cattle milk processing and marketing characteristics among agro-pastoralists in North West Nigeria

The study was aimed at analysing the fundamental characteristics of milk collection, processing and marketing among agro-pastoralists in North West Nigeria. A three stage (multi-stage) sampling technique was used for the study. The first stage is the purposive selection of four States (Jigawa, Kaduna, Kano and Katsina States purposively selected based on the high concentration of agro-pastoralists). In the second stage, two Local Government Areas (LGA) from each of the State were purposively selected. The third stage involved the use of snowball sampling method for the selection of communities where agropastoralist were interviewed using structured questionnaire. Two communities were selected per LGA. Data were collected from 157 respondents from the target populatuion out of sampled agro-pastoral households. The survey instrument was pretested and subjected to face validity. The data obtained were analysed using descriptive statistics of frequency counts and percentages. The average length of time for milk storage before processing was 1 hour and 41 minutes. Pasteurization was the method of choice used to prevent milk spoilage by 63.8% of respondents in all the States considered in this study. Almost all (91.2%) of the respondents market their milks. Spoilage of milk during the period before processing was reported as the highest constraint to milk production, processing and marketing in all the four States. Inadequate equipment and milk loss during processing were also reported as constraints by 18.9 and 14.7%, respectively. Low quality of milk, especially during dry season, also constitute a constraint to about 4% of the respondents. The agro-pastoralists in North West Nigeria are engaged in peasantry profitable ventures of milk processing and marketing. Most of them are not members of groups and cooperatives. Their volume of trade in milk processing and marketing can be greatly enhanced if they are organized into productive groups along the value chain. Past efforts at organizing milk processors and marketers into groups and cooperatives need to be revisited by relevant agencies of government and non-government organizations.

Şanlıurfa İli Süt Sığırı İşletmelerindeki Süt Verim Kaybına Isı Stresinin Etkisi

Bu çalışma, Şanlıurfa ilinin ilçelerine ait sıcaklık nem indekslerini (SNİ) hesaplayarak ısı stresinin süt kayıpları üzerindeki etkisini belirlemek amacıyla yapılmıştır. Araştırmanın veri setini Diyarbakır Meteoroloji Bölge Müdürlüğünden temin edilen Şanlıurfa ilinin 10 ilçesine ait 1999-2019 yılları arasındaki meteorolojik veriler ile Türkiye İstatistik Kurumu’ndan (TUİK) alınan 2019 yılı sağmal inek sayıları oluşturmuştur. Araştırmada, ilin tüm ilçelerine ait mayıs-eylül ayları arasındaki SNİ değerleri, SNİ değerinin alansal dağılımı, inek başına günlük süt kayıpları ile günlük toplam süt kayıpları belirlenmiştir. Araştırmada, SNİ değerlerinin kritik değerleri aştığı ay ve ilçeler dikkate alındığında yüksek SNİ değerlerine bağlı olarak oluşan inek başına günlük süt kaybının en yüksek olduğu ilçe ağustos ayında 10.828 g ile Şanlıurfa merkez, en düşük olduğu ilçe ise haziran ayında 163 g ile Hilvan olarak tespit edilmiştir. Böylece SNİ kaynaklı süt kayıplarının en fazla temmuz ve ağustos aylarında şekillendiği ve en çok etkilenen ilçelerin ise Şanlıurfa Merkez ve Akçakale olduğu belirlenmiştir. Ayrıca TUİK’ten alınan Şanlıurfa il ve ilçelerinin 2019 yılına ait 2 yaşın üstündeki toplam süt inek sayıları kullanılarak elde edilen toplam ortalama günlük süt kayıplarının en fazla yaşandığı ilçe ağustos ayında 27283 kg ile Siverek, en az yaşandığı ilçe ise haziran ayıda 71 kg ile Bozova olarak tespit edilmiştir. Söz konusu aylarda en fazla kaybın yaşandığı ilçeler süt ineği popülasyonuna bağlı olarak Şanlıurfa merkez, Akçakale ve Siverek olmuştur. Sonuç olarak, Şanlıurfa süt işletmelerinde, özellikle temmuz ve ağustos aylarında, ısı stresi nedeniyle önemli süt verim kayıplarının yaşandığı belirlenmiştir. Isı stresi ve süt kaybını önlemek için yüksek çevre sıcaklığının olduğu dönemlerde bakım-yönetim uygulamalarının iyileştirilmesi faydalı olacaktır.

Evaluation of customized dry-period strategies in dairy cows

Shortening or omitting the dry period to improve the energy balance in early lactation have the trade-offs of reduction in milk production and loss of opportunity for dry-cow therapy (DCT; i.e., intramammary antibiotic use at dry-off). Customized dry-period strategies (i.e., deciding upon DCT and dry-period length per cow) could mitigate negative effects of short or no dry periods on milk production and udder health and simultaneously retain benefits from improved energy balance and fertility. In this study, we evaluated 3 decision trees to customize dry-period strategies for individual cows. In the control tree (CT), all cows had a 60-d dry period, with DCT if somatic cell count (SCC) was >150,000 cells/mL before dry-off. In decision tree 1 (T1), parity 1 and parity >1 cows were assigned DCT if SCC was ≥150,000 cells/mL and SCC ≥50,000 cells/mL, respectively; whereas in decision tree 2 (T2), the threshold for DCT was SCC ≥200,000 cells/mL for all animals. In T1 and T2, cows with DCT were assigned a 60-d dry period, whereas cows without DCT were assigned a 30-d or 0-d dry period if their milk production remained >12 kg/d at 67 and 37 d before calving, respectively. Cows were monitored from 8 wk before to 14 wk after calving. Milk production and composition, SCC, body condition score, body weight, and occurrence of treatment for disease (related to calving and start of lactation) were compared between CT (n = 61 cows), T1 (n = 59 cows), and T2 (n = 63 cows). Effects of decision trees (CT, T1, T2) and of dry-period strategies (60-d dry with or without antibiotics, 30-d dry, or 0-d dry) on measured variables were analyzed separately with mixed models, effects on udder-health status with a logistic regression, and occurrence of treatment for diseases with a Pearson chi-squared test. In T1, 36% of cows qualified for 30-d and 2% for 0-d dry periods, whereas in T2 this was 51% and 30% for 30-d and 0-d dry periods, respectively. Compared with CT, cows in T1 and T2 on average produced more milk in the 8 wk before calving (0.2 vs. 3.9 vs. 7.1 kg/d in CT vs. T1 vs. T2), and less in the 14 wk after calving (40.0 vs. 37.0 vs. 35.2 kg/d in CT vs. T1 vs. T2). There was no difference in udder-health status in the transition period among decision trees. In the first 14 wk after calving, recovery of body weight was greater for T2 than CT and T1. Overall, 30-d and 0-d dry periods reduced milk revenues, but this might be financially compensated by improved cow health with customized dry-period strategies.

Lactation curve model with explicit representation of perturbations as a phenotyping tool for dairy livestock precision farming

In the context of dairy farming, ruminant females often face challenges inducing perturbations that affect their performance and welfare. A key issue is how to assess the effect of perturbations and provide metrics to quantify how animals cope with their environment. Milk production dynamics are good candidates to address this issue: i) they are easily accessible, ii) overall dynamics throughout lactation process are well described and iii) perturbations are visible through milk losses. In this study, a perturbed lactation model (PLM) with explicit representation of perturbations was developed. The model combines two components: i) the unperturbed lactation model that describes a theoretical lactation curve, assumed to reflect female production potential and ii) the perturbation model that describes all the deviations from the unperturbed lactation model with four parameters: starting date, intensity and shape (collapse and recovery). To illustrate the use of the PLM as a phenotyping tool, it was fitted on a data set of 319 complete lactations from 181 individual dairy goats. A total of 2 354 perturbations were detected, with an average of 7.40 perturbations per lactation. Loss of milk production for the whole lactation due to perturbations varied between 2 and 19% of the milk production predicted by the unperturbed lactation model. The number of perturbations was not the major factor explaining the loss of milk production, suggesting that there are different types of animal response to challenges. By incorporating explicit representation of perturbations in a lactation model, it was possible to determine for each female the potential milk production, characteristics of each perturbation and milk losses induced by perturbations. Further, it was possible to compare animals and analyze individual variability. The indicators produced by the PLM are likely to be useful to move from raw data to decision support tools in dairy production.

Milk losses and dynamics during perturbations in dairy cows differ with parity and lactation stage

Milk yield dynamics during perturbations reflect how cows respond to challenges. This study investigated the characteristics of 62,406 perturbations from 16,604 lactation curves of dairy cows milked with an automated milking system at 50 Belgian, Dutch, and English farms. The unperturbed lactation curve representing the theoretical milk yield dynamics was estimated with an iterative procedure fitting a model on the daily milk yield data that was not part of a perturbation. Perturbations were defined as periods of at least 5 d of negative residuals having at least 1 day that the total daily milk production was below 80% of the estimated unperturbed lactation curve. Every perturbation was characterized and split in a development and a recovery phase. Based hereon, we calculated both the characteristics of the perturbation as a whole, and the duration, slopes, and milk losses in the phases separately. A 2-way ANOVA followed by a pairwise comparison of group means was carried out to detect differences between these characteristics in different lactation stages (early, mid-early, mid-late, and late) and parities (first, second, and third or higher). On average, 3.8 ± 1.9 (mean ± standard deviation) perturbations were detected per lactation in the first 305 d after calving, corresponding to an estimated 92.1 ± 135.8 kg of milk loss. Only 1% of the lactations had no perturbations. On average, 2.3 kg of milk was lost per day in the development phase, while the recovery phase corresponded to an average increase in milk production of 1.5 kg/d, and these phases lasted an average of 10.1 and 11.6 d, respectively. Perturbation characteristics were significantly different across parity and lactation stage groups, and early and mid-early perturbations in higher parities were found to be more severe with faster development rates, slower recovery rates, and higher milk losses. The method to characterize perturbations can be used for precision phenotyping purposes that look into the response of cows to challenges or that monitor applications (e.g., to evaluate the development and recovery of diseases and how these are affected by preventive actions or treatments).

Clinical Metritis and Endometritis in Diary Cattle: A Review

Reproduction is one of the key pillars of production in many herds and individual animals. In female animals, reproduction can be affected by uterine diseases including metritis and endometritis. The objective of this review is to understand metritis and endometritis, diagnosis and treatment approaches, and the economic impact of uterine inflammations. Metritis is inflammation of the wall of the uterus, whereas endometritis is inflammation of the functional lining of the uterus, called the endometrium. Clinically, they are characterized by an enlarged uterus containing a watery red-brown fluid to viscous off-white purulent uterine discharge, which often has a fetid odor within 10 to 14-days after postpartum period in clinical metritis whereas clinical endometritis can also be observed its clinical signs after 21-days postpartum period. The risk factors for the occurrence of clinical metritis and endometritis include extrinsic factors include calving season and nutrition whereas intrinsic factors include retained fetal membrane (RFM), dystocia, metabolic disturbance, negative energy balance (NEB) and other non-specific diseases. These factors disturbing the normal physiology and weaken the immune system of dairy cattle. The factors favor the multiplication of pathogenic bacteria and cause inflammation of the uterus and results in metritis and endometritis. This result in increased conception interval increase the number of inseminations, loss of milk and meat production, marked drop in fertility and increase the cost of treatment. Clinical metritis and endometritis can be diagnosed by clinical symptoms and cytological examinations. Clinical metritis and endometritis can be treated by anti-inflammatory drugs flunixin meglumine, antibiotics (pens-trip and long-acting oxytetracycline), intrauterine infusion by using saline or iodine tincture solutions. Clinical metritis and endometritis are the most frequent uterine disorders in dairy cows causing decreased fertility leading to high economic losses. Therefore, management of these production diseases can be achieved by early diagnosis and treatment, supplementation of balanced feed containing minerals, vitamins, appropriate proteins and carbohydrates, good quality management during and after calving of the female animals.

Predicting dairy cattle heat stress using machine learning techniques

The objectives of the study were to use a heat stress scoring system to evaluate the severity of heat stress on dairy cows using different heat abatement techniques. The scoring system ranged from 1 to 4, where 1 = no heat stress; 2 = mild heat stress; 3 = severe heat stress; and 4 = moribund. The accuracy of the scoring system was then predicted using 3 machine learning techniques: logistic regression, Gaussian naïve Bayes, and random forest. To predict the accuracy of the scoring system, these techniques used factors including temperature-humidity index, respiration rate, lying time, lying bouts, total steps, drooling, open-mouth breathing, panting, location in shade or sprinklers, somatic cell score, reticulorumen temperature, hygiene body condition score, milk yield, and milk fat and protein percent. Three different treatments, namely, portable shade structure, portable polyvinyl chloride pipe sprinkler system, or control with no heat abatement, were considered, where each treatment was replicated 3 times with 3 second-trimester lactating cows. Results indicate that random forest outperformed the other 2 methods, with respect to both accuracy and precision, in predicting the sprinkler group's score. Both logistic regression and random forest were consistent in predicting scores for control, shade, and combined groups. The mean probability of predicting non-heat-stressed cows was highest for cows in the sprinkler group. Finally, the logistic regression method worked best for predicting heat-stressed cows in control, shade, and combined. The insights gained from these results could aid dairy producers to detect heat stress before it becomes severe, which could decrease the negative effects of heat stress, such as milk loss.

Evaluating the impact of heat stress as measured by temperature-humidity index (THI) on test-day milk yield of small holder dairy cattle in a sub-Sahara African climate

This study evaluates the effect of heat stress on milk production and describes the pattern of response of milk yield to increasing heat load, using temperature-humidity index (THI) on test-day milk records of small holder dairy cattle herds in the sub-Saharan African climate of Tanzania. Climate data obtained from aWhere, an agricultural weather data platform (http://www.awhere.com) was analysed with 14,367 first lactation test day milk records of 3511 dairy cows collected between 2016 and 2019. THI was calculated from daily maximal temperatures and daily minimum humidity. Three sets of analysis were performed. In the first and second analysis, two mixed effect repeatability models were fitted with THI treated as a categorical variable grouped into 5 classes (THI1= [61 - 66], THI2= [67 - 71], THI3= [72 - 78], THI4=[79 - 81], THI5=[82 - 86]), to obtain least squares estimates of THI effect on milk production, and as a continuous variable within THI classes to identify THI thresholds at which milk yield started to decline. In the third analyses, one quadratic polynomial regression (POL) and three regression spline functions namely piecewise linear spline function (PLF), natural splines function (NSF) and cubic splines function (CSF) were fitted to determine the average effect of THI on milk yield in the population and describe the pattern of response of milk yield to increasing head load.The results show that heat stress reduced milk yield by 4.16% to 14.42% across THI groups, with daily milk yield being the highest in THI1 (7.40±0.39 litres) and the lowest in THI4 (6.33±0.32).Regression coefficients within groups showed significant daily milk yield decrease in THI2 (-0.09) and THI3 (-0.06), but not for other THI classes, indicating that cows experienced heat stress between THI values of 67 and 76 and milk loss plateaued afterwards, suggesting that the animals acclimatized to heat stress conditions beyond THI value of 76. At the population level, THI and its squared term were significantly negatively and positively (-0.61, 0.004) associated with milk production, indicating a non-linear relationship between milk yield and THI. The CSF model showed better goodness of fit and predictive ability than other models for predicting future population response of milk yield to heat stress in small holder dairy farms in Tanzania.Herd management strategies and animal husbandry measures are needed in small holder dairy farms in Tanzania to minimize the impact of heat stress on milk yield and income of the farmers.

Influence of endometritis on milk yield of zero-grazed dairy cows on smallholder farms in Rwanda

Endometritis being a post-partum uterine infection in dairy cows is likely with substantial production loss through reduction in milk yield (MY), discarded milk during treatment and withdrawal period, and increased cost of veterinary treatment. This study quantified the influence of endometritis on MY of zero-grazed dairy cows managed on smallholder farms in Rwanda. The study enrolled a total of 461 cows within their 21 to 60 days in milk to examine for clinical endometritis (CLE) and subclinical endometritis (SCLE). A cow was considered having endometritis if it was positive for at least one test (CLE or SCLE), otherwise was negative. The MY data were collected prospectively from endometritis positive and negative cows for 30-day post-endometritis diagnosis. Compared to cows negative for endometritis, the positive endometritis cows were 2.4 times more (29.7 vs. 70.3%) with daily MY 15.3% lower (7.5 ± 0.2 vs. 8.9 ± 0.3 litres; p<0.05), representing a reduction of 1.4 ± 0.2 litres of milk/cow/day. Of the CLE positive cows, 33.4% (104/311) were treated using different veterinary drugs, which resulted in 23.5% more discarded milk compared (p<0.05) to untreated positive cows. Discarded milk was higher (p<0.05) among cows treated with oxytetracycline (65.9 ± 4.4 litres) compared to cows treated with procaine penicillin G and dihydrostreptomycin (35.5 ± 2.7 litres). The percentage of total milk loss was much higher (45.6%) among CLE positive cows that received treatment compared to the untreated cows (16.3%). These results demonstrate a strong association between MY loss and endometritis. A timely diagnosis and treatment of the disease is recommended using conventional veterinary drugs that have zero withholding time for milk to reduce the MY loss and associated economic loss, estimated at 154 US$ in a lactation.

Effect of vaccination with a Mannheimia haemolytica subunit vaccine on milk yield in lactating dairy cows

Many herds in the US use a mannheimia vaccine in lactating dairy cows as an aid in reducing the impact of bovine respiratory disease (BRD). Producers often report significant post-vaccination milk drop following the use of some mannheimia vaccines. A review of the literature found no reports documenting milk loss following administration of mannheimia vaccines, but there were reports documenting milk loss from other vaccines of up to 4 lb (1.8 kg)/d for 3 d. This adds to the cost of vaccinating the lactating herd and should be considered when developing vaccination programs. If milk income over feed cost is $0.13/lb ($0.28/kg) then the 3-d milk loss can add up to decreased revenue from milk sales of $1.56 per cow. The objective of this study was to quantify the milk loss associated with the use of Mannheimia haemolytica subunit vaccine* (MHSV) in lactating dairy cows.