Development and Application of Nested PCR Assay for Detection of Dairy Cattle-Derived Cyclospora sp.

To develop a nested PCR assay for the detection of cattle-derived Cyclospora sp., two pairs of primers were designed on the basis of the cattle-derived Cyclospora sp. sequences. These primers selectively amplified a 168-bp DNA fragment of the 18S rRNA gene of cattle-derived Cyclospora sp. With these primers, a nested PCR assay for the detection of cattlederived Cyclospora sp. was developed. The nested PCR assay was specific and there is no cross-reaction with other parasites, such as Eimeria spp., Cryptosporidium spp., Giardia sp., Toxoplasma sp., Trichuris sp. and cattle ciliate. The assay was able to detect as low as 2.85 × 10^-2 fg of the control positive DNA. The results of the detection of clinical samples indicated that the assay coincided with microscopic examination. The results show that the nested PCR assay will be an effective tool for the detection of Cyclospora sp. in cattle feces.

Review： Sugar beets as a substitute for grain for lactating dairy cattle

Dairy cows are customarily given grains and highly digestible byproduct ingredients as additions to forage to support milk production. In many parts of the world growing seasons are short, and the grain crops that can be grown may not provide adequate yields. Sugar beets, on the other hand are relatively hardy, and dry matter yields surpass the yields of most grain crops. There are however, perceptions that beets may not be suitable as a feed ingredient due to the fact that the storage form of carbohydrate is sugar rather than starch. With little analytical support, sugar has been rejected in many feeding programs with the view that sugar reduces rumen pH, fiber digestion and microbial yield. This review explores available facts revolving around these concerns. Information regarding the feeding of sugar beets is provided and the use of sugar beets as a partial replacement for grain is proposed.

The Investigation of Main Pathogens Causing Dairy Cattle Recessive Mastitis in Eastern Hebei

[Objective]This paper aimed to determine the main pathogens causing dairy cattle recessive mastitis in eastern Hebei and provide certain reference for local veterinarians and cow farmers to prevent and cure the disease.[Method]512 cows from 5 different farms in eastern Hebei were selected,and LMT,milk ph test and somatic cell direct counting methods were combined and used to conduct recessive mastitis＇ s epidemiological investigation,as well as isolate and identify the pethogens.[Result]The results indicated that the incidence of recessive mastitis is 60.7%（311 / 512）,bacteria isolation rate reached 87.8%（273 /311）.Total 81 isolates,belonging to 3 classes and 5 types were identified in milk samples of positive milk area from 273 cows with recessive mastitis.Among which,19 isolates were Streptococcus,accounting for 23.45%.Staphylococcus had 31 isolates,accounting for 38.27%.Enterobacter had 3,accounting for 3.7%.Other unshaped had 28 isolates,accounting for 34.6%.[Conclusion] The main pathogens caused dairy cattle recessive mastitis in eastern Hebei were Streptococcus agalactiae and Staphylococcus aureus.

Digital Dermatitis in Dairy Cattle Is Still a Serious Problem in Western Europe

Bacterial infections are quite common in dairy cattle,and frequently related to internal organ systems like e.g.respiratory,intestinal and udder infections.Lameness in dairy cattle is mainly caused by both infectious and non-infectious hoof problems and these have different etiological background.At the moment(2018)the major infectious hoof disorders are DD(Digital Dermatitis)and IP(Interdigital Phlegmon).These are all due to infection from the area where dairy cows normally live and more or less intensive contact with“contaminated”manure.This paper gives insight in these different dermatitis problems cows are daily confronted with,with a focus on infectious hoof disorders as a more or less permanent problem in today’s dairy farming.

Meta-analysis of calorimeter data to establish relationships between methane and carbon dioxide emissions or oxygen consumption for dairy cattle

Recent developments suggest the use of other gases such as carbon dioxide(CO_2) to estimate methane(CH_4)emissions from livestock,yet little information is available on the relationship between these two gases for a wide range of animals.A large respiration calorimeter dataset with dairy cattle(n=987 from 30 experiments)was used to investigate relationships between CH_4 and CO_2 production and oxygen(O_2)consumption and to assess whether the predictive power of these relationships could be improved by taking into account some dietary variables,including forage proportion,fibre and metabolisable energy concentrations.The animals were of various physiological states(young n=60,dry cows n=116 and lactating cows n=811)and breeds(Holstein-Friesian cows n=876,Jersey×Holstein-Friesian n=47,Norwegian n=50 and Norwegian×Holstein-Friesian n=14).The animals were offered forage as a sole diet or a mixture of forage and concentrate(forage proportion ranging from 10 to 100%,dry matter basis).Data were analysed using a series of mixed models.There was a strong positive linear relationship between CH_4and CO_2,and observations within an experiment were very predictable(adjusted R^2=0.93).There was no effect of breed on the relationship between CH_4 and CO_2.Using O_2 instead of CO_2 to predict CH_4 production also provided a very good fit to the observed empirical data,but the relationship was weaker(adjusted R^2=0.86).The inclusion of dietary variables to the observed CO_2 emissions,in particular forage proportion and fibre concentration,provided a marginal improvement to the prediction of CH_4.The observed variability in the CH_4:CO_2 ratio could only marginally be explained by animal physiological state(lactating vs.dry cows and young cattle)and dietary variables,and thus most likely reflected individual animal differences.The CH_4:CO_2 ratio can therefore be particularly useful to identify low CH_4 producing cows.These findings indicate that CO_2 production data can be used to accurately predict CH_4 emissions to generate large scale data for management and genetic evaluations for the dairy industry.

FeedEfficiencyService: An architecture for the comparison of data from multiple studies related to dairy cattle feed efficiency indices

The increased demand for food worldwide,the reduced land availability for livestock pro-duction,the increasing cost of animal feed and the need for mitigating livestock-related greenhouse gas emissions have driven the search for animal feeding systems that proves more efficient.To tackle this problem,we propose the use of computational support to help researchers compare data on feed efficiency,therefore improving economic and environ-mental gains.As a solution,we present an integrative architecture capable of combining heterogeneous data from multiple experiments related to dairy cattle feed efficiency indices.The proposed architecture,called FeedEfficiencyService,classifies animals according to feed efficiency indices and allows visualizations through ontologies and inference engines.The results obtained from a case study with researchers from the Brazilian Agri-cultural Research Corporation–Dairy Cattle(EMBRAPA)demonstrate that this architecture is a supporting tool in their daily work routine.The researchers highlighted the importance of the proposed architecture as it allows analyzing animal data,comparing experiments,having reliable data analyses,and standardizing and organizing data from experiments.The novelty of our approach is the use of ontologies and inference engines to enable the discovery of new knowledge and new relationships between data from feed efficiency-related experiments.We store such data,relationships,and analyses of results in an inte-grated repository.This solution ensures unified access to the processing history and data from diverse experiments,including those conducted at external research centers.

Performance of Dairy Cows Supplemented with By-Pass Fat under Heat Stress Conditions

The objective of this study was to determine the effect of supplementation with a protected fat source on the productive response, metabolic environment and physiological indicators in Holstein cows under heat stress conditions during a 12-week experimental period. Thirty Holstein cows were distributed in 15 blocks by parity (2.0 ± 1.1), days in milk (182 ± 80) and milk production (29.4 ± 5.7 kg·day-1) at the beginning of the trial and randomly assigned within each block to the following treatments (diets): SPF: supplementation with protected fat or WPF: without supplementation with protected fat. All the cows were kept in a dry-lot where they were given a partial mixed ration (PMR) ad libitum while in the milking parlor they received individual supplementation depending on the treatment. The SPF diet contained 4.0 kg·day-1 concentrate in pellet form + 0.6 kg·day-1 ground corn grain + 0.7 kg·day-1 protected fat, while the WPF diet was similar to that offered in SPF, but the protected fat was isoenergetically replaced by ground corn grain. The fat supplement contained fats of animal and vegetable origin and microencapsulation was used for its preparation. Total dry matter and metabolic energy intakes were similar (p > 0.05) between treatments. Fat corrected milk (4% FCM) production was higher (p = 0.04), while energy corrected milk and fat productions tended (p = 0.06) to be higher in cows from the SPF group, without effects (p > 0.05) on the rest of the milk production and composition parameters. These results could be attributed to an improvement in the efficiency of the use of the energy consumed. Protected fat supplementation neither modified the metabolic profile, nor reduced the respiratory rate and body temperature of heat-stressed cows. Future research is needed to explain this latter result.

The Effect of Dietary Vegetable Oilseeds Supplement on Fatty Acid Profiles in Milk Fat from Lactating Dairy Cows

To determine the effect of dietary supplementation with vegetable oilseeds on the composition of bovine milk fatty acids （FAs）, 40 Holstein dairy cows were used with a complete randomized design. At the beginning of the experiment, the cows were 150±25 day in milk （DIM）. Total duration of the experiment was six weeks. Measurements were made during the last three weeks. Cows in four treatments were fed with a basal diet （CT） or basal diet supplemented with either whole full fat soybean （WFS）, full fat expanded soybean （FPS） or whole full fat soybean with whole cottonseed and full fat expanded soybean （MIX）. The composition of the milk fat was analyzed by gas chromatography. Relative to control, the conjugated linoleic acid （CLA） concentration in milk fat from cows on FPS was significantly increased by 83.88% （P〈 0.05）. The proportions of C12：0 were decreased by 35.7, 35.51, and 38.65% in milk fat from cows on WFS, MIX, and FPS compared with cows on CT. Similar decreases in C 14：0 were 23.83, 24.85, and 31.48% in WFS, MIX, and FPS treatments, respectively. Feeding vegetable oilseeds increased the proportion of healthy FAs （mainly CLA）, whereas decreased the concentratiofi of C12：0 and C14：0. Therefore, milk and dairy products would have higher nutritive and therapeutic value.

Effects of 5% Biological Compound Premix on Milk Perform ance and Quality in Dairy Cow

This study was to investigate the effect of biological compound premix on the performance and milk quality in dairy cows. Twenty Holstein cows, with the similar age, parity, lactating month, gestation period, milk quantity and body weight, were randomly divided into two groups. The cows in two groups were fed with either common compound premix as control or 5% biological compound premix as treatment group. Two treatments contained same basal diet but different composi- tions of premix. The feeding experiment lasting 74 days displayed that daily milk quantity in treatment group was significantly higher than control group （P 〈 0.05 ）. The milk fat percentage was increased significantly in treatment group with the extended lactation time than control group （P 〈 0.05 ）. The milk protein and solids percentage were raised, but no significant difference was found between the two treatments （P 〉0.05 ）. The results indicated that 5% biological compound premix supplied in basal diet could facilitate to increase the milk performance and to ameliorate the milk quality of dairy cows.

Weighted single-step GWAS and RNA sequencing reveals key candidate genes associated with physiological indicators of heat stress in Holstein cattle

Background: The study of molecular processes regulating heat stress response in dairy cattle is paramount for developing mitigation strategies to improve heat tolerance and animal welfare. Therefore, we aimed to identify quantitative trait loci(QTL) regions associated with three physiological indicators of heat stress response in Holstein cattle, including rectal temperature(RT), respiration rate score(RS), and drooling score(DS). We estimated genetic parameters for all three traits. Subsequently, a weighted single-step genome-wide association study(WssGWAS) was performed based on 3200 genotypes, 151,486 phenotypic records, and 38,101 animals in the pedigree file. The candidate genes located within the identified QTL regions were further investigated through RNA sequencing(RNA-seq) analyses of blood samples for four cows collected in April(non-heat stress group) and four cows collected in July(heat stress group).Results: The heritability estimates for RT, RS, and DS were 0.06, 0.04, and 0.03, respectively. Fourteen, 19, and 20 genomic regions explained 2.94%, 3.74%, and 4.01% of the total additive genetic variance of RT, RS, and DS, respectively. Most of these genomic regions are located in the Bos taurus autosome(BTA) BTA3, BTA6, BTA8, BTA12, BTA14, BTA21, and BTA24. No genomic regions overlapped between the three indicators of heat stress, indicating the polygenic nature of heat tolerance and the complementary mechanisms involved in heat stress response. For the RNA-seq analyses, 2627 genes were significantly upregulated and 369 downregulated in the heat stress group in comparison to the control group. When integrating the WssGWAS, RNA-seq results, and existing literature, the key candidate genes associated with physiological indicators of heat stress in Holstein cattle are: PMAIP1, SBK1, TMEM33, GATB, CHORDC1, RTN4IP1, and BTBD7.Conclusions: Physiological indicators of heat stress are heritable and can be improved through direct selection. Fifty-three QTL regions associated with heat stress indicators confirm the polygenic nature and complex genetic determinism of heat tolerance in dairy cattle. The identified candidate genes will contribute for optimizing genomic evaluation models by assigning higher weights to genetic markers located in these regions as well as to the design of SNP panels containing polymorphisms located within these candidate genes.

The use of milk Fourier transform midinfrared spectra and milk yield to estimate heat production as a measure of efficiency of dairy cows

Background:Transformation of feed energy ingested by ruminants into milk is accompanied by energy losses via fecal and urine excretions,fermentation gases and heat.Heat production may differ among dairy cows despite comparable milk yield and body weight.Therefore,heat production can be considered an indicator of metabolic efficiency and directly measured in respiration chambers.The latter is an accurate but time-consuming technique.In contrast,milk Fourier transform mid-infrared(FTIR)spectroscopy is an inexpensive high-throughput method and used to estimate different physiological traits in cows.Thus,this study aimed to develop a heat production prediction model using heat production measurements in respiration chambers,milk FTIR spectra and milk yield measurements from dairy cows.Methods:Heat production was computed based on the animal’s consumed oxygen,and produced carbon dioxide and methane in respiration chambers.Heat production data included 16824-h-observations from 64 German Holstein and 20 dual-purpose Simmental cows.Animals were milked twice daily at 07:00 and 16:30 h in the respiration chambers.Milk yield was determined to predict heat production using a linear regression.Milk samples were collected from each milking and FTIR spectra were obtained with MilkoScan FT 6000.The average or milk yield-weighted average of the absorption spectra from the morning and afternoon milking were calculated to obtain a computed spectrum.A total of 288 wavenumbers per spectrum and the corresponding milk yield were used to develop the heat production model using partial least squares(PLS)regression.Results:Measured heat production of studied animals ranged between 712 and 1470 kJ/kg BW0.75.The coefficient of determination for the linear regression between milk yield and heat production was 0.46,whereas it was 0.23 for the FTIR spectra-based PLS model.The PLS prediction model using weighted average spectra and milk yield resulted in a cross-validation variance of 57%and a root mean square error of prediction of 86.5 kJ/kg BW0.75.The ratio of performance to deviation(RPD)was 1.56.Conclusion:The PLS model using weighted average FTIR spectra and milk yield has higher potential to predict heat production of dairy cows than models applying FTIR spectra or milk yield only.

Assessing Animal Disease Prevalence and Mortality in Smallholder Dairy Farms under Contrasting Management Practices and Stressful Environments in Tanzania

In dairy farming, deploying effective animal husbandry practices minimise disease infections and animal mortality. This improves animal health and welfare status, which is important in tropical smallholder dairy farming, where animals are persistently exposed to multiple environmental stresses. The hypothesis of this study was that animals managed in positive deviants and typical farms suffer different levels of disease infections and mortality, whether under low- or high-stress environments. The study adopted a two-factor nested design with farms contrasting in the level of animal husbandry (positive deviants and typical farms) nested within environments contrasting in the level of environmental stresses (low- and high-stress). A total of 1,999 animals were observed over 42 month period in the coastal lowlands and highlands of Tanzania. The disease prevalence was lower (p < 0.05) in positive deviant farms than in typical farms under low-stress (10.13 vs. 33.61 per 100 animal-years at risk) and high-stress (9.56 vs. 57.30 per 100 animal-years at risk). Cumulative disease incidence rate was also lower (p < 0.05) in positive deviant farms than in typical farms under low-stress (2.74% vs. 8.44%) and high-stress (2.58% vs. 14.34%). The probability of death for a disease infected dairy cattle was relatively lower in positive deviant farms compared to typical farms under low-stress (0.57% vs. 8.33%) and high-stress (0.60% vs. 6.99%). Per 100 animal-years at risk, the mortality density of cattle was lower (p < 0.05) in positive deviant farms compared to typical farms, 15.10 lower in low-stress and 2.60 lower in high-stress. These results show that compared to typical farms, positive deviant farms consistently attained (p < 0.05) lower animal disease infections and subsequent deaths, regardless of the level of environmental stress that the animals were exposed to. This implies that positive deviant farms deployed animal husbandry practices that more effectively minimised animal disease infections and deaths and therefore could maintain their animals in better health and welfare status.

Nutrition, Metabolic Status and Reproductive Efficiency in Dairy Herds

Nutrition of transition period in dairy cows dramatically increases requirements for energy, glucose, amino acids and other nutrients in dairy cows and, parallel to that, feed intake is depressed. An insufficient or imbalanced nutrient intake might lead to the malfunction of organs, causing reproductive failure. To minimize the metabolic/reproductive damage caused by negative energy balance (NEBAL), feeding of a glucogenic and lipogenic diet containing fat-enriched supplements is recommended. In heat-stressed dairy cows, the reduction of dry matter intake causes an energy deficit, thereby accentuating NEBAL. Heat stress may also have a direct impact on oocyte quality due to the high ovarian temperatures. The intrauterine environment is also compromised in heat-stressed cows, with reduced blood flow to the uterus and increased uterine temperature;this may impair embryonic development, increase early embryonic loss and reduce the proportion of successful inseminations. Postpartum NEBAL suppresses immune function and promotes metabolic disorders, potentially explaining relationships between infectious and noninfectious transition disorders. In postpartum dairy cows, pathologic ovarian phenomena including ovulatory (cystic corpora lutea) and non-ovulatory (follicular and luteal cysts) forms frequently occur causing decreased fertility. The main objective of this review was summarizing the most relevant information regarding nutrition and reproduction in dairy cows.

Management and prevention of mastitis:A multifactorial approach with a focus on milking,bedding and data-management

Mastitis is a complex, multifactorial disease. Pathogens, cows and farmers （via management） all play a role. It is costly and annoying for the farmer and threatens the image of the entire dairy industry. Prevention and control of mastitis is based on multiple principles that have been known for a long time. To implement them successfully, they should be put forward by a motivated and motivating advisor that transfers the existing knowledge to the farmer. When the changes are data-driven, applied by an encouraged farmer through a farm-specific implementation, prevention and control of mastitis will be successful and result in happy cows, happy farmers, happy advisors, happy consumers, and a happy industry. Nationwide projects focussing on communication and transfer of existing knowledge in prevention and control are very helpful in reaching high numbers of farmers and advisors and harmonizing the message brought by different parties. This paper gives an overview of multifactorial approach of mastitis management and prevention with a focus on milking, bedding and data-analysis.

Construction and Identification of Mammary Gland-specific Expression Vector of Bovine Tracheal Antimicrobial Peptide (TAP)

[ Objective] This study aimed to construct nmnmm_ry gland-specific expression vector of bovine tracheal antimicrobial peptide （TAP） gene. [ Method] TAP gene of dairy cattle was amplified from the mammary gland tissue by RT-PCR using a pair of primers which were designed according to bovine TAP cDNA se- quence （NM_174776） in GenBank, and then cloned into pMD19-T Simple vector for sequencing. The recombinant plasmid was digested using EcoRI and KpnI, the target gene fragment was recovered and inserted into general mammary gland-specific expression vector pBLG-EGFP harboring enhanced green fluorescent protein （ EGFP）, and transfected into bovine mammary epithelial cells （bMEC）, COS-7 cells and lactating rabbit mmmnary gland tissue by lipofectin transfection. The ex- pression of green fluorescent protein in transfected cells was detected under fluorescence microscopy, and the expression of TAP mRNA in rabbit mammary gland tis- sue was detected by semi-quantity RT-PCR. [ Result] The constructed mammary gland-specific expression vector pBLG-EGFP-TAP specifically expressed EGFP in transfected bMECs. In addition, semi-quantitative RT-PCR result showed that the expression level of TAP mRNA in rabbit mammary gland tissue was significantly enhanced after transfeeted with pBLG-EGFP-TAP. [ Conclusion] The mammary gland-specific expression vector pBLG-EGFP-TAP was successfully constructed, which provided important materials for further investigation of expression characteristics of TAP gene and prevention of bovine mastitis by using genetic engineering technology.

Genome scan of pigmentation traits in Friesian-Jersey crossbred cattle

Pigmentation traits expressed in animals are visual characteristics that allow us to distinguish between breeds and between strains within breed. The objective of this study was to map quantitative trait loci （QTLs） affecting the pigmentation traits in approximately 800 F2 grand daughter dairy cattle from a Holstein-Friesian and Jersey cross breed cattle. Traits analyzed included pigmentation phenotypes on the body, teat and hoop. The phenoypes were collected from digital photos or visual inspection of live animals. QTL mapping was implemented using half-sib and line-of-descent inheritance models. Our analysis initially detected a number of significant QTLs on chromosomes： 2, 6, 13, 15, 18 and 22. The significant QTLs were divided into two groups： one group influencing the pigmentation color and the other group affecting the absence or level of pigmentation. The most significant QTL peaks were observed on Bovine taurus autosome 18 （BTA18） close to melanocortin 1 receptor （MC1R） for the color traits, on BTA6 close to the receptor tyrosine kinase （K/T） and BTA22 close to microphthalmia-associated transcription factor （M/TF） gene for the spotting traits. Association studies were conducted for candidate regions or genes known to affect pigmentation in dairy cattle.

Meta-analysis quantifying the potential of dietary additives and rumen modifiers for methane mitigation in ruminant production systems

Increasingly countries are seeking to reduce emission of greenhouse gases from the agricultural industries,and livestock production in particular,as part of their climate change management.While many reviews update progress in mitigation research,a quantitative assessment of the efficacy and performance-consequences of nutritional strategies to mitigate enteric methane(CH_(4))emissions from ruminants has been lacking.A meta-analysis was conducted based on 108 refereed papers from recent animal studies(2000-2020)to report effects on CH4 production,CH_(4) yield and CH_(4) emission intensity from 8 dietary interventions.The interventions(oils,microalgae,nitrate,ionophores,protozoal control,phytochemicals,essential oils and 3-nitrooxypropanol).Of these,macroalgae and 3-nitrooxypropanol showed greatest efficacy in reducing CH_(4) yield(g CH_(4)/kg of dry matter intake)at the doses trialled.The confidence intervals derived for the mitigation efficacies could be applied to estimate the potential to reduce national livestock emissions through the implementation of these dietary interventions.