Female Dairy Cattle Research Articles

Characterization of bovine vaginal microbiota using 16S rRNA sequencing: associations with host fertility, longevity, health, and production

Due to their potential impact on the host’s phenotype, organ-specific microbiotas are receiving increasing attention in several animal species, including cattle. Specifically, the vaginal microbiota of ruminants is attracting growing interest, due to its predicted critical role on cows’ reproductive functions in livestock contexts. Notably, fertility disorders represent a leading cause for culling, and additional research would help to fill relevant knowledge gaps. In the present study, we aimed to characterize the vaginal microbiota of a large cohort of 1171 female dairy cattle from 19 commercial herds in Northern France. Vaginal samples were collected using a swab and the composition of the microbiota was determined through 16S rRNA sequencing targeting the V3–V4 hypervariable regions. Initial analyses allowed us to define the core bacterial vaginal microbiota, comprising all the taxa observed in more than 90% of the animals. Consequently, four phyla, 16 families, 14 genera and a single amplicon sequence variant (ASV) met the criteria, suggesting a high diversity of bacterial vaginal microbiota within the studied population. This variability was partially attributed to various environmental factors such as the herd, sampling season, parity, and lactation stage. Next, we identified numerous significant associations between the diversity and composition of the vaginal microbiota and several traits related to host’s production and reproduction performance, as well as reproductive tract health. Specifically, 169 genera were associated with at least one trait, with 69% of them significantly associated with multiple traits. Among these, the abundances of Negativibacillus and Ruminobacter were positively correlated with the cows’ performances (i.e., longevity, production performances). Other genera showed mixed relationships with the phenotypes, such as Leptotrichia being overabundant in cows with improved fertility records and reproductive tract health, but also in cows with lower production levels. Overall, the numerous associations underscored the complex interactions between the vaginal microbiota and its host. Given the large number of samples collected from commercial farms and the diversity of the phenotypes considered, this study marks an initial step towards a better understanding of the intimate relationship between the vaginal microbiota and the dairy cow’s phenotypes.

Enhancing dairy cow population through decreasing calf mortality and increasing calving rate in Indonesia: a system dynamics approach

Abstract The dairy industry in Indonesia is facing significant challenges due to the rates of calf mortality and low calving rates. Calf mortality and calving rate became critical factors that influence the sustainability of the dairy cow population. This study aimed to assess reproduction management by decreasing calf mortality and increasing calving rates to enhance the dairy cow population in Indonesia. This study employed secondary data in 2022 using technical parameter coefficients from previous research. A causal loop diagram and a simulation model using a system dynamics approach were developed to investigate the dynamics of the dairy cow population under different scenarios of calf mortality and calving rates from 2023 to 2030. The results showed that decreasing calf mortality by 2% may increase dairy cow population by 1,991 head/year (0.31%), heifer population by 417 head/year (0.63%), and adult female dairy cattle population by 389 head/year (0.09%). The finding of this study also showed that increasing calving rate by 5% may increase dairy cow population by 17,854 head/year (2.75%), heifer population by 3,698 head/year (5.56%), and adult female dairy cattle population by 2,137 head/year (0.51%). It is concluded that reducing calf mortality rates and improving calving rates should be prioritized to enhance the dairy cow population in Indonesia.

Sperm-borne tsRNAs and miRNAs analysis in relation to dairy cattle fertility

Sperm small non-coding RNAs (sncRNAs), such as microRNAs (miRNAs) and tRNA-derived small RNAs (tsRNAs), have been found to have implications for male fertility and play a role in the intergenerational transmission of specific phenotypes by influencing the early embryo's physiological processes in various animal species. This study postulates that there exists a correlation between sperm small non-coding RNAs (sncRNAs) and bull fertility, which in turn can influence the fertility of offspring through the modulation of early embryo development. To investigate this hypothesis, we generated comparative libraries of sperm sncRNAs from sires exhibiting high (n = 3) versus low bull fertility (n = 3), as well as high (n = 3) versus low daughter fertility (n = 3), as determined by the industry-standard Bull fertility index and Daughter fertility index. In total, 12 tsRNAs carried by sperm (11 down-regulated and 1 up-regulated) were found to be associated with bull fertility, while 19 tsRNAs (11 down-regulated and 8 up-regulated) were found to be associated with daughter fertility (q < 0.05, Log2foldchange>±1.5, base mean > 50). Notably, tRX-Glu–NNN–3811 exhibited potential as a biomarker for predicting fertility in both male and female dairy cattle. Moreover, a total of six miRNAs sperm-borne (two up-regulated and four down-regulated) and 35 miRNAs (27 up-regulated and eight down-regulated) exhibited a significant correlation with both bull fertility and daughter fertility individually (p < 0.05, base mean > 50, log2foldchange>±1.5), two microRNAs, namely miR-2385-5p (down-regulated) and miR-98 (up-regulated), exhibit a significant association (p < 0.05, base mean > 50, log2foldchange>±1.5) with the fertility of both bulls and daughter. The targets of these two microRNAs were subsequently identified and integrated with the transcriptomic database of the embryonic cells at the two-cell stage, which is known to be indicative of embryonic competence. The KEGG analysis revealed a potential correlation between these targets and choline metabolism, a crucial factor in embryonic epigenetic programming.In summary, the findings of this study indicate that sperm-borne small non-coding RNAs (sncRNAs) hold promise as biomarkers for predicting and enhancing fertility in dairy cattle. Furthermore, it is plausible that these sncRNAs may exert their effects on daughter fertility by targeting genes in the early embryo.

Detection of Antibodies Brucella abortus in dairy cattle in Puspo District, Pasuruan using Rose Bengal Test and Complement Fixation Test

Brucellosis was an infectious disease caused by the genus brucella. Brucellosis in dairy cattle was caused by Brucella abortus that impaction an abortion. The aim of this study was to determine the presence of antibodies of the Brucella abortus in adult female dairy cattle in the Puspo district Pasuruan using Rose Bengal Test (RBT) and Complement Fixation Test (CFT). A descriptive analysis method with quantitative approach was used in this study. Meanwhile, interviews were conducted to get supporting information from the farmer. Used 100 samples. The results of the study showed 2% samples considered positive brucellosis tested by RBT. To confidence false-positive result, RBT test was followed by CFT. After tested by CFT, in this study there were no brucella antibodies in adult female dairy cattle in Puspo district, Pasuruan.

Sarcocystis species in bovine carcasses from a Belgian abattoir: a cross-sectional study

BackgroundSarcocystis species are obligatorily heteroxenous parasites, of which some are zoonotic, representing a public health and economic impact. This study investigated the occurrence of Sarcocystis spp. in cattle sampled from a Belgian slaughterhouse.MethodsA total of 200 carcasses were included in the study, sampled during 10 sampling days. The sedimentation method was applied to isolate the sarcocysts from both heart and diaphragm muscles collected from each carcass. Multiplex PCR, PCR–RFLP as well as cox1 gene sequencing techniques were applied serially on collected sarcocysts for species identification.ResultsSarcocystis spp. were detected in 64% (128/200; 95% CI 57–71%) of the sampled carcasses. Female dairy cattle presented the highest Sarcocystis occurrence rate (91%) as well as the highest Sarcocystis species diversity compared to female beef and male beef. Sarcocystis spp. were detected more often in the heart muscles than in the diaphragm among female beef (p < 0.001) and dairy carcasses (p = 0.001), while in male carcasses no significant difference was observed (p = 0.763). The effect of age was not significant in male carcasses (p = 0.872), while the odds of finding sarcocysts significantly increased with age (p = 0.003) within both types of female carcasses. S. cruzi was the most prevalent species and was found in 56.5% (113/200) of the carcasses, followed by S. hominis (21.0%, 42/200), S. bovifelis (12.5%, 25/200), S. bovini (2.0%, 4/200), S. hirsuta (1.5%, 3/200) and S. heydorni (0.5%, 1/200). Six different species were detected in the diaphragm, while only two species were recovered from the heart. S. cruzi was the most prevalent species in heart, while in the diaphragm, this was S. hominis.ConclusionsThe detection of S. hominis in 21% of the sampled carcasses presents a potential food safety issue, and further research is warranted into controlling this infection.Graphical

Detection of Brucellosis in Dairy Cattle in Turen District Malang Regency using Rose Bengal Test (RBT) and Complement Fixation Test (CFT) Methods

The purpose of this research was to detect Brucellosis in female dairy cattle in Turen District, Malang Regency. A total of 78 samples were used in this research taken from 351 total population of female dairy cattle that have been calculated based on the slovin formula. The methods used in this research were Rose Bengal Test (RBT) for the screening test and continued with Complement Fixation Test (CFT) for the confirmation test. The results RBT of this research clearly showed that positive results from 10 samples were confirmed as a final diagnostic test of Brucellosis using CFT. CFT showed a positive result from 9 samples and negative in 1 sample. The percentage of Brucellosis occurrence in the Turen District was recorded at 11.5%. Moreover, Turen District also became an area with a high Brucellosis occurrence (&gt;2%).

Evaluation of female fertility in dairy cattle enterprises – A review

&#x0D; &#x0D; &#x0D; The aim of this article was to review the state of fertility of female dairy cattle in South Africa and to compare it with international efforts at improving fertility. Fertility in dairy cows is defined as the ability to conceive from first insemination soon after calving and to carry the calf full term to calving. It is one of the main profit drivers in the dairy industry and is a complex trait that is influenced by the environment, genetics, and their interaction. Generally, there has been a decline in dairy cow fertility across breeds worldwide because of intense selection for milk yield, milk components, and body conformation traits. In addition, most fertility traits are negatively correlated to milk production traits. Milk production has been the focal point of selection programmes as it is linked directly to the profitability of the dairy enterprise. The low heritability of fertility traits is one of the factors that discouraged efforts to include fertility in genetic evaluations. However, owing to its economic importance, female fertility was later included in the breeding objectives for dairy cattle in several countries. Although most fertility traits are heritable to a low degree, some additive genetic variability can be exploited.&#x0D; &#x0D; &#x0D;

Localization of putative pituitary stem/progenitor cells in female dairy cattle.

Research on sex-determining region Y-box 2 (SOX2)-positive pituitary stem/progenitor cells, as a source of hormone-producing cells, is progressing rapidly in rodents. However, the stem/progenitor cells supplying hormone-producing cells that are essential for growth, reproduction, and lactation in bovines have not yet been identified. In this study, we characterized SOX2-positive cells in the pituitary gland of dairy cattle (Holstein heifers) after sexual maturity. Immunofluorescence analysis revealed that the localization pattern of SOX2-positive cells in the dairy cattle pituitary gland was similar to that observed in the rodent pituitary gland; the marginal cell layer (MCL), dense cell clusters, and single cells scattered in the parenchyma of the anterior lobe. Furthermore, most of the SOX2-positive cells were positive for the pituitary stem/progenitor cell niche markers E-cadherin and cytokeratin 8+18, which have been reported in rodents. In addition, in the MCL of the anterior lobe, there was a subpopulation of SOX2-positive cells positive for paired-related homeobox 1 and 2, whereas negative for S100β. Moreover, in the parenchyma of the anterior lobe, co-localization of SOX2 and pituitary hormones was infrequent. In summary, this study reveals the localization of putative pituitary stem/progenitor cells positive for SOX2 in dairy cattle. These results provide valuable information to support further investigation of cell supply in the dairy cattle pituitary gland.

Early social experiences do not affect first lactation production traits, longevity or locomotion reaction to group change in female dairy cattle

Under natural conditions cows and their calves live together. In dairy practice, calves are separated from their mothers within hours after birth and then housed individually. This study investigated the effects of the presence of the dam during the colostrum feeding period and subsequent group housing during early ontogeny on reproduction, milk performance and locomotion at first lactation as well as on longevity in female dairy cattle. Forty female calves were allocated to 1 of 4 treatments according to a 2 × 2 factorial design. The treatments were with or without mother during the 4 days after birth and either single housing or housing in groups of 4 calves between 1 and 8 weeks of age. Thereafter all calves were managed according to routines of the farm until they became primiparous lactating cows. Data about locomotion, milk yield, milking duration and body weight were collected every milking. Information about calving, inseminations, pregnancy and departure of the animal from the herd/group were added to records. We predicted that females raised with early mother contact and group housing will have higher performance as dairy cows. None of the seven performance variables was affected by either the age of separation from the dam or by the type of housing 8 weeks of life. The results indicate that neither provision of maternal care for a few days nor group housing for the duration of milk feeding bring any advantage or disadvantage for later performance in female dairy cattle.

Findings in cattle consigned to Victorian knackeries between 2009 and 2018.

To describe the causes of death or culling in cattle in Victoria, Australia, through surveillance at knackeries. Data were collected from 2797 adult cattle consigned to four Victorian knackeries over a 10-year period (2009-2018, inclusive). Cattle were sampled either at the point of collection or at a knackery. A single best-fit diagnosis was assigned to each case to describe the cause of loss. Sampled cattle were predominantly female dairy cattle originating from the three main dairying regions in Victoria. The most commonly diagnosed conditions were calving paralysis (6.8%), followed by mastitis (6.4%), hypocalcaemia (6.4%) and dystocia (5.9%). "Unknown" accounted for 24.2% of the cattle examined. This study provides a unique insight into the causes of death and culling in cattle consigned to Victorian knackeries. The periparturient period was identified as a high risk period for knackery consignment in adult female cattle.

Morphometrical study of bovine kidneys with and without mild histological lesions

The objective of this study was to determine the renal dimensions in adult cows and to investigate whether they are affected by the breed, the age of the animals and the presence of subclinical renal histopathological lesions. The kidneys of 57 adult female dairy (44 Holstein) and beef (13 Limousine-Cross) cattle aged≥2years obtained at an abattoir were used for the purpose of the study. The greatest pole-to-pole length and the maximum width were measured with a digital caliper. A renal sample obtained from a central pole of each kidney underwent histopathologic examination. Renal dimensions were significantly affected by the breed and the age of the animals without however been affected by the presence of mild histopathologically detected lesions. The renal size was significantly higher in Holstein cows compared to Limousine-Cross ones and significantly lower in cows aged more than 6years than the youngest ones. Left kidney was shorter and wider in the majority of animals. These results indicate that breed and age of animals are significant factors that affect renal size in cows. They further prove that mild histologically detected renal lesions do not significantly alter renal dimensions. Although no significant difference was detected, the obtained results tend to confirm the well documented morphological difference (asymmetry) in cattle between right and left kidney.

Sero-prevalence and risk factors of infectious bovine rhinotracheitis virus (type 1) in Meru County, Kenya

The aim of the study was to determine the antibody sero-prevalence of Bovine Herpesvirus-1 which cause Infectious Bovine Rhinotracheitis (IBR) and to identify risk factors associated with BHV-1 antibody seropositivity among smallholder dairy farms in Meru County, Kenya.A cross-sectional study was conducted in the Naari area of Meru County, Kenya between September–October 2016 and March–April 2017. The 149 farmers were randomly selected from members of the Naari Dairy Farmers Cooperative Society who were actively delivering milk to the society at the time of the study. Serum samples were obtained from 403 female dairy cattle. Farm level management and animal factors were collected through direct interviews with the owner or someone who was knowledgeable about the animals. All serum samples were processed with an indirect enzyme-linked immunosorbent assay (gB ELISA) to determine the presence of antibodies to BHV-1.The overall farm-level and animal-level sero-prevalences of BHV-1 antibodies were 30.9 % (95 % CI: 23.6%–39.0%) and 17.4 % (95 % CI: 13.8%–21.4%), respectively. In the final multivariable analysis, the factors significantly associated with BHV-1 antibodies included; age of the dairy cattle (OR = 1.200, p = 0.001), age of the principal female farmers (OR = 0.182, p = 0.001) and rearing goats in the farm (OR = 26.77, p = 0.000). There was a significant interaction between rearing goats on the farm and age of the dairy cattle (p < 0.010); younger cattle seemed to have been exposed to BHV or a cross-reacting caprine herpesvirus when goats were on the farm.The results showed that BHV-1 was circulating among the cattle population in the Naari area of Meru County. Given that there is not BHV-1 vaccination use in this study population, training on the importance of biosecurity and vaccination for BHV-1 are recommended to reduce the transmission and impacts of BHV-1.

Choice of artificial insemination beef bulls used to mate with female dairy cattle

Understanding the preferences of dairy cattle producers when selecting beef bulls for mating can help inform beef breeding programs as well as provide default parameters in mating advice systems. The objective of the present study was to characterize the genetic merit of beef artificial insemination (AI) bulls used in dairy herds, with particular reference to traits associated with both calving performance and carcass merit. The characteristics of the beef AI bulls used were compared with those of the dairy AI bulls used on the same farms. A total of 2,733,524 AI records from 928,437 females in 5,967 Irish dairy herds were used. Sire predicted transmitting ability (PTA) values and associated reliability values for calving performance and carcass traits based on national genetic evaluations from prior to the insemination were used. Fixed effects models were used to relate both genetic merit and the associated reliability of the dairy and beef bulls used on the farm with herd size, the extent of Holstein-Friesian × Jersey crossbreeding adopted by the herd, whether the herd used a technician insemination service or do-it-yourself, and the parity of the female mated. The mean direct calving difficulty PTA of the beef bulls used was 1.85 units higher than that of the dairy bulls but with over 3 times greater variability in the beef bulls. This 1.85 units equates biologically to an expectation of 1.85 more dystocia events per 100 dairy cows mated in the beef × dairy matings. The mean calving difficulty PTA of the dairy AI bulls used reduced with increasing herd size, whereas the mean calving difficulty PTA of the beef AI bulls used increased as herd size increased from 75 cows or fewer to 155 cows; the largest herds (>155 cows) used notably easier-calving beef bulls, albeit the calving difficulty PTA of the beef bulls was 3.33 units versus 1.67 units for the dairy bulls used in these herds. Although we found a general tendency for larger herds to use dairy AI bulls with lower reliability, this trend was not obvious in the beef AI bulls used. Irrespective of whether dairy or beef AI bulls were considered, herds that operated more extensive Holstein-Friesian × Jersey crossbreeding (i.e., more than 50% crossbred cows) used, on average, easier calving, shorter gestation-length bulls with lighter expected progeny carcasses of poorer conformation. Mean calving difficulty PTA of dairy bulls used increased from 1.39 in heifers to 1.79 in first-parity cows and to 1.82 in second-parity cows, remaining relatively constant thereafter. In contrast, the mean calving difficulty PTA of the beef bulls used increased consistently with cow parity. Results from the present study demonstrate a clear difference in the mean acceptable genetic merit of beef AI bulls relative to dairy AI bulls but also indicates that these acceptable limits vary by herd characteristics.

Genetic variability in the humoral immune response to bovine herpesvirus-1 infection in dairy cattle and genetic correlations with performance traits

Bovine herpesvirus-1 (BoHV-1) is a viral pathogen of global significance that is known to instigate several diseases in cattle, the most notable of which include infectious bovine rhinotracheitis and bovine respiratory disease. The genetic variability in the humoral immune response to BoHV-1 has, to our knowledge, not ever been quantified. Therefore, the objectives of the present study were to estimate the genetic parameters for the humoral immune response to BoHV-1 in Irish female dairy cattle, as well as to investigate the genetic relationship between the humoral immune response to BoHV-1 with milk production performance, fertility performance, and animal mortality. Information on antibody response to BoHV-1 was available to the present study from 2 BoHV-1 sero-prevalence research studies conducted between the years 2010 to 2015, inclusive; after edits, BoHV-1 antibody test results were available on a total of 7,501 female cattle from 58 dairy herds. National records of milk production (i.e., 305-d milk yield, fat yield, protein yield, and somatic cell score; n = 1,211,905 milk-recorded cows), fertility performance (i.e., calving performance, pregnancy diagnosis, and insemination data; n = 2,365,657 cows) together with animal mortality data (i.e., birth, farm movement, death, slaughter, and export events; n = 12,853,257 animals) were also available. Animal linear mixed models were used to quantify variance components for BoHV-1 as well as to estimate genetic correlations among traits. The estimated genetic parameters for the humoral immune response to BoHV-1 in the present study (i.e., heritability range: 0.09 to 0.16) were similar to estimates previously reported for clinical signs of bovine respiratory disease in dairy and beef cattle (i.e., heritability range: 0.05 to 0.11). Results from the present study suggest that breeding for resistance to BoHV-1 infection could reduce the incidence of respiratory disease in cattle while having little or no effect on genetic selection for milk yield or milk constituents (i.e., genetic correlations ranged from -0.13 to 0.17). Moreover, even though standard errors were large, results also suggest that breeding for resistance to BoHV-1 infection may indirectly improve fertility performance while also reducing the incidence of mortality in older animals (i.e., animals >182 d of age). Results can be used to inform breeding programs of potential genetic gains achievable for resistance to BoHV-1 infection in cattle.

Effects of gender of dairy or beef cattle and the number of pair of permanent incisors on carcass traits

Effects of group of cattle (gender of dairy or beef cattle) and number of pair of permanent incisors (0-4 pairs) on carcass traits were investigated. Data collected from 2,059 carcasses were obtained from beef cattle cooperative in 2016. Carcass traits included slaughter weight (wt.), hot carcass wt., percentage of hot or chilled carcass wt., chilling loss, skin wt., and marbling score. Factors included group of cattle and number of pair of permanent incisors observed in each cattle group, while slaughter wt. was a co-variable in the statistical model. Descriptive statistics were used to analyze marbling score. Results showed that group of cattle affected slaughter wt., hot carcass wt., percentage of hot or chilled carcass wt., skin wt. (P&lt;0.0001), and chilling loss (P&lt;0.05). Number of pair of permanent incisors within each cattle group affected all carcass traits (p&lt;0.05), except chilling loss (p&gt;0.05). Female and male beef cattle in all ages had higher hot carcass wt. and percentage of hot or chilled carcass wt. than female and male dairy cattle. The highest marbling score of 5 was found in female and male beef and female dairy cattle with 4 pairs of permanent incisors. However, majority of cattle had marbling score 2.

Using body measurements to estimate live weight of dairy cattle in low-input systems in Senegal

ABSTRACTWe investigated the prediction of live weight (LW) of dairy cattle in low- to medium-input systems in Senegal, based on measurements of heart girth (HG) and height at the withers (HW). A total of 459 female dairy cattle, mainly comprising indigenous Zebu and their crosses with Guzerat or Bos Taurus, were weighed (kg), and their HG (cm) and HW (cm) determined. Farmers were asked to provide their own weight estimates for each animal. The single explanatory variable that explained the most variation in LW was HG. The best model to predict LW from HG for the overall data was with an adjusted R2 of 0.85 and a root mean square error of 34.25 kg corresponding to 11.10% of the mean LW. This model predicted the LW of 91–100% of cows and 64–100% of heifers within 20% of their true-live weight, in the weight range of about 100–500 kg. In comparison, farmers could only estimate the LW of about a quarter of their animals within 20% of their true LW. This weight prediction equation, when translated into a weigh band, could provide a simple and reliable method for cattle keepers to estimate the weight of studied cattle breed types.

Presence of Ureaplasma diversum in the genital tracts of female dairy cattle in Mato Grosso State, Brazil.

Ureaplasma diversum infection in bovine females may result in various reproductive problems, including granular vulvovaginitis, abortion, weak calves, salpingitis, and spontaneous abortion. The presence of U. diversum in a dairy bovine population from midwestern Brazil has not been established. The aim of this study was to determine whether U. diversum was present in dairy cattle from midwestern Brazil using polymerase chain reaction (PCR). Vulvovaginal mucus was analyzed from 203 cows located in six municipalities in the north region of Mato Grosso State, Brazil. A total of 25% of dairy cows with vulvovaginitis were positive for U. diversum. The factors evaluated were included in a multivariable logistic regression model with the presence of at least one positive cow in the herd serving as the dependent variable. Three variables were significantly associated with a U. diversum-positive PCR and were included in the final multivariable model: number of parities, vulvar lesions, and reproductive problems. For each new parity, the chance of U. diversum infection decreased 0.03-fold, indicating that cows with the highest number of parities were more protected. The presence of vulvar lesions was increased 17.6-fold in females positive for U. diversum, suggesting that this bacterium could be related to the red granular lesions in the vulvar mucosa, whereas reproductive problems were increased 7.6-fold. However, further investigations should be conducted to ascertain the effects of U. diversum in association with other mycoplasma species in the herds studied.

Liver copper concentrations in cull cattle in the UK: are cattle being copper loaded?

With the release of the Department for the Environment, Food and Rural Affairs/Advisory Committee on Animal Feed Guidance Note for Supplementing Copper to Bovines it was noted that the current...

2004 Methane and Nitrous Oxide Emissions from Manure Management in South Africa.

Simple SummaryLivestock manure management is one of the main sources of greenhouse gas (GHG) emissions in South Africa producing mainly methane and nitrous oxide. The emissions from this sub-category are dependent on how manure is stored. Liquid-stored manure predominantly produces methane while dry-based manure enhances mainly production of nitrous oxide. Intergovernmental Panel on Climate Change (IPCC) guidelines were utilized at different tier levels in estimating GHG emissions from manure management. The results show that methane emissions are relatively higher than nitrous oxide emissions with 3104 Gg and 2272 Gg respectively in carbon dioxide global warming equivalent.Manure management in livestock makes a significant contribution towards greenhouse gas emissions in the Agriculture; Forestry and Other Land Use category in South Africa. Methane and nitrous oxide emissions are prevalent in contrasting manure management systems; promoting anaerobic and aerobic conditions respectively. In this paper; both Tier 1 and modified Tier 2 approaches of the IPCC guidelines are utilized to estimate the emissions from South African livestock manure management. Activity data (animal population, animal weights, manure management systems, etc.) were sourced from various resources for estimation of both emissions factors and emissions of methane and nitrous oxide. The results show relatively high methane emissions factors from manure management for mature female dairy cattle (40.98 kg/year/animal), sows (25.23 kg/year/animal) and boars (25.23 kg/year/animal). Hence, contributions for pig farming and dairy cattle are the highest at 54.50 Gg and 32.01 Gg respectively, with total emissions of 134.97 Gg (3104 Gg CO2 Equivalent). Total nitrous oxide emissions are estimated at 7.10 Gg (2272 Gg CO2 Equivalent) and the three main contributors are commercial beef cattle; poultry and small-scale beef farming at 1.80 Gg; 1.72 Gg and 1.69 Gg respectively. Mitigation options from manure management must be taken with care due to divergent conducive requirements of methane and nitrous oxide emissions requirements.

Trends in export of dairy Holstein heifers from the United States

A general overview of the export and testing requirements is given for bred female dairy cattle from the United States (US) to Turkey, Mexico, and Russia, the top three export markets. Disease-by-disease serologic test results are presented for 7,339 Holstein dairy heifers tested in quarantine in southeastern Chester County, Pennsylvania for export to Turkey from June 2010 to October 2011. Management practices to decrease the prevalence of diseases of importance to the export market are reviewed. Prevalence rates of serologically positive heifers tested during the quarantine period using the enzyme linked-immunosorbent assay were: bluetongue virus (BTV) 4.9%, Mycobacterium avium subsp. paratuberculosis (MAP) 0.65%, and bovine leukemia virus (BLV) 5.7%. Prevalence rate of bovine viral diarrhea virus - persistently infected (BVDV PI) heifers using pooled polymerase chain reaction was 0.68%. Because of the high prevalence of BLV in US cattle, most if not all heifers are routinely screened for BLV prior to purchase and entry into quarantine. Some of the heifers in this data set originating from endemic BTV states were pre-screened for BTV. Because of pre-screening for BLV prior to purchase for export, the prevalence of BLV reported was lower than would be expected in the general population of heifers in the US. The prevalence of BTV would depend on whether heifers came from BTV free or endemic states. Dairy herds wanting to market heifers for export should apply management practices known to decrease the prevalence of BTV, BLV, MAP, and BVDV PI.