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1.  Culling patterns in selected Minnesota swine breeding herds. 
This investigation was conducted to study culling patterns in swine breeding herds. Data were obtained from 89 Minnesota swine breeding herds and included 5918 sows and 1324 gilts for a total of 7242 culled femaled. Each producer was involved for 12 consecutive months. They were asked to record every female that was removed from the herd, the reason for its culling and its parity. The annual culling rate for the sample averaged 50%, but varied considerably between herds ranging from 15% to 85%. Culled females had produced an average of 3.77 litters. Half of the females culled did not produce more than three litters. Reproductive failure accounted for 32% of all removals. The average parity of the females culled in that category was only 2.37: almost 33% were gilts. Failure to conceive represented 75% of all females culled for reproductive failure. Proportionally, culling as a result of anestrus was higher in gilts. It accounted for 33% of all gilts culled for reproductive failure which was twice as much as for sows. Inadequate performance accounted for 17% of all removals. These sows had produced an average of 5.11 litters. These results indicated that few animals were culled on the basis of first litter performance. Old age comprised 14% of all removals and the average parity at culling for this category was 7.11. Death accounted for 12% and the average parity for these females was 3.40. Locomotor problems and peripartum problems were the cause of 28% and 23% of all deaths, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
PMCID: PMC1255374  PMID: 3453273
2.  Effects of bovine leukemia virus infection on production and reproduction in dairy cattle. 
The purpose of this study was to determine the effects of bovine leukemia virus (BLV) infection on production, reproduction and longevity in dairy cattle. The study population was a commercial Holstein dairy herd of approximately 400 milking cows. Cattle were tested for antibodies to BLV at least annually for three years and when culled. Four groups of culled cows were compared: seronegative cows (n = 79), seropositive cows without lymphocytosis (n = 176), seropositive cows with lymphocytosis (> or = 9,000 lymphocytes/microliter) (n = 74), and seropositive cows with lymphosarcoma (n = 29). Seropositive groups of cows were bred more times and had longer calving intervals than seronegative cows. The seropositive groups had greater 305-day ME (mature equivalent) FCM (3.5% fat-corrected milk) per lactation and were older when culled than seronegative cows. However, the percent fat per lactation was greater in seronegative cows. In the last complete lactation, differences in 305-day ME FCM, days open and cull age between groups were reduced and none were significant (p > 0.05). In the cull lactation, only cows with lymphocytosis had reduced milk production relative to seronegative cows, although this difference was not significant. After adjustment for initial production and reproductive values, only seropositive nonlymphocytotic cows were culled at a significantly older age than seronegative cattle. Lymphocytotic cows were culled four months younger on average than nonlymphocytotic seropositive cows. Hence, BLV infected cows had greater milk production on average than uninfected cows. Adverse effects of BLV infection were primarily limited to lymphocytotic cows which were culled earlier and had reduced milk production in the cull lactation.
PMCID: PMC1263558  PMID: 1477797
3.  Causes of culling in dairy cows and its relation to age at culling and interval from calving in Shiraz, Southern Iran 
Veterinary Research Forum  2012;3(4):233-237.
This study was designed to investigate causes of culling in industrial dairy herds in Fars province and to describe the pattern of reason-specific culling with respect to age of animal and interval from calving to culling. A total number of 9 dairy herds were selected for the study and information about culling reasons, birth date, last calving date and culling date was collected for culled cows during 2005-2006. Infertility (32.6% of all culls) was the most prevalent reason of culling followed by mastitis (6.5%). The time interval from last calving to culling averaged 240 days (SD = 176) and nearly 28% of cows were culled in the first 100 days after calving. Mean age of animals at culling was 6 years (SD = 2.7) and median was 5.7 years. In Cox proportional hazard model for calving to culling interval, infertility (hazard ratio [HR] = 0.26) showed lower risk whereas mastitis (HR = 2.40), left displaced abomasum (HR = 2.60) and peripartum problems (HR = 2.60) had higher risk of culling compared with voluntary cull. In the Cox model for age at culling, risk of culling was significantly higher for infertility (HR = 1.70), left displaced abomasum (HR = 3.15), and peripartum problems (HR = 2.10) compared with voluntary culling. In conclusion, farmers tend to keep infertile cows for longer period from calving to culling while infertile cows are generally culled at younger age. Also, early culling appeared to have a high proportion of culls in the studied herds.
PMCID: PMC4313041
Dairy herds; Cox model; Culling; Infertility; Iran
4.  Effects of kefir on coccidial oocysts excretion and performance of dairy goat kids following weaning 
The aim of this study was to investigate effects of kefir, a traditional source of probiotic, on coccidial oocysts excretion and on the performance of dairy goat kids following weaning. Twin kids were randomly allocated to one of two groups at weaning. Kids of the first group received 20 ml of kefir daily for 6 weeks (KEF), while kids in the control group were given a placebo (CON). Individual faecal samples were regularly (n = 18 per kid) taken to quantify the number of coccidial oocysts per gram of faeces (OpG). There were no differences between the groups in terms of body weight development (P > 0.05) and feed consumption. Kids of both groups were not able to consume enough feed to meet their nutrient requirements during the first 3 weeks following weaning. KEF had a lower frequency of OpG positive samples than CON (P = 0.043). Kefir did not affect the maximum oocyst excretion and age of the kids at the highest oocyst excretion (P > 0.05). KEF shed numerically 35% lower coccidial oocysts than the controls, which corresponded to a statistical tendency (P = 0.074) in lowering Log-OpG in comparison to CON. While KEF had a lower frequency of OpG positive samples and tended to shed lower OPG by around one-third, the frequency of diarrhea, level of highest oocyst excretion, and performance of the kids remained unaffected. Therefore, it is concluded that overall effects of kefir do not have a significant impact on sub-clinical infection and performance in weaned kids under relatively high-hygienic farming conditions.
doi:10.1007/s11250-011-0039-3
PMCID: PMC3345116  PMID: 22189816
Growth; Host nutrition; Parasite; Probiotic; Sub-clinical coccidiosis; Life Sciences; Zoology; Veterinary Medicine
5.  Heritability of longevity in Large White and Landrace sows using continuous time and grouped data models 
Background
Using conventional measurements of lifetime, it is not possible to differentiate between productive and non-productive days during a sow's lifetime and this can lead to estimated breeding values favoring less productive animals. By rescaling the time axis from continuous to several discrete classes, grouped survival data (discrete survival time) models can be used instead.
Methods
The productive life length of 12319 Large White and 9833 Landrace sows was analyzed with continuous scale and grouped data models. Random effect of herd*year, fixed effects of interaction between parity and relative number of piglets, age at first farrowing and annual herd size change were included in the analysis. The genetic component was estimated from sire, sire-maternal grandsire, sire-dam, sire-maternal grandsire and animal models, and the heritabilities computed for each model type in both breeds.
Results
If age at first farrowing was under 43 weeks or above 60 weeks, the risk of culling sows increased. An interaction between parity and relative litter size was observed, expressed by limited culling during first parity and severe risk increase of culling sows having small litters later in life. In the Landrace breed, heritabilities ranged between 0.05 and 0.08 (s.e. 0.014-0.020) for the continuous and between 0.07 and 0.11 (s.e. 0.016-0.023) for the grouped data models, and in the Large White breed, they ranged between 0.08 and 0.14 (s.e. 0.012-0.026) for the continuous and between 0.08 and 0.13 (s.e. 0.012-0.025) for the grouped data models.
Conclusions
Heritabilities for length of productive life were similar with continuous time and grouped data models in both breeds. Based on these results and because grouped data models better reflect the economical needs in meat animals, we conclude that grouped data models are more appropriate in pig.
doi:10.1186/1297-9686-42-13
PMCID: PMC2879236  PMID: 20465803
6.  Low seroprevalence of Coxiella burnetii in Boer goats in Missouri 
BMC Research Notes  2014;7:421.
Background
Goats are known reservoirs of Coxiella burnetii, the etiologic agent of Q fever. However, there has been very little research on the prevalence of C. burnetii exposure and risk in meat goats farmed in the US. Banked serum samples were secondarily tested for C. burnetii specific antibodies.
Findings
The animal and herd-level seroprevalence estimates for C. burnetii were 1.2% (3/249) and 4.2% (1/24) respectively. Within-herd seroprevalence ranged from 0% to 1.2%.
Conclusions
This study indicates that seroprevalence of C. burnetii in Boer goats raised in Missouri was low, but it does not preclude the existence of a higher level of infection in Missouri’s meat goat herds. This result is inconclusive because this study was disadvantaged by the small number of individual animal and herds tested, which compromised the statistical power of this study to detect a possible higher seroprevalence of C. burnetii in this population, if present. More research is warranted to corroborate the preliminary findings reported here in order to determine the public health significance C. burnetii infection risks associated with contemporary goat production systems in the US.
doi:10.1186/1756-0500-7-421
PMCID: PMC4102339  PMID: 24994554
Coxiella burnetii; Goats; Q fever; Missouri; United States
7.  Risk of tuberculosis cattle herd breakdowns in Ireland: effects of badger culling effort, density and historic large-scale interventions 
Veterinary Research  2014;45(1):109.
Bovine tuberculosis (bTB) continues to be a problem in cattle herds in Ireland and Britain. It has been suggested that failure to eradicate this disease is related to the presence of a wildlife reservoir (the badger). A large-scale project was undertaken in the Republic of Ireland during 1997–2002 to assess whether badger removal could contribute to reducing risk of cattle herd breakdowns in four areas. During the period of that “four area” study, there was a significant decrease in risk in intensively culled (removal) areas relative to reference areas. In the present study, we revisit these areas to assess if there were any residual area effects of this former intervention a decade on (2007–2012). Over the study period there was an overall declining trend in bTB breakdown risk to cattle herds. Cattle herds within former removal areas experienced significantly reduced risk of breakdown relative to herds within former reference areas or herds within non-treatment areas (OR: 0.53; P < 0.001). Increased herd breakdown risk was associated with increasing herd size (OR: 1.92-2.03; P < 0.001) and herd bTB history (OR: 2.25-2.40; P < 0.001). There was increased risk of herd breakdowns in areas with higher badger densities, but this association was only significant early in the study (PD*YEAR interaction; P < 0.001). Badgers were culled in areas with higher cattle bTB risk (targeted culling). Risk tended to decline with cumulative culling effort only in three counties, but increased in the fourth (Donegal). Culling badgers is not seen as a viable long-term strategy. However, mixed policy options with biosecurity and badger vaccination, may help in managing cattle breakdown risk.
Electronic supplementary material
The online version of this article (doi:10.1186/s13567-014-0109-4) contains supplementary material, which is available to authorized users.
doi:10.1186/s13567-014-0109-4
PMCID: PMC4230509  PMID: 25344430
8.  Trends in cow numbers and culling rate in the Irish cattle population, 2003 to 2006 
Irish Veterinary Journal  2008;61(7):455-463.
Cows are the main economic production units of Ireland's cattle industry. Therefore, demographic information, including overall numbers and survival rates, are relevant to the Irish agricultural industry. However, few data are available on the demographics of cows within a national population, either in Ireland or elsewhere, despite the recent development of comprehensive national cattle databases in many EU Member States. This study has sought: to determine the rate of cow culling from the national herd; to determine the rate of culling by type (dairy, beef), age, method of exit, date of exit and interval between last calving and exit; to calculate the national cow on-farm mortality rate; and to compare the Irish rates with published data from other countries. This work was conducted using data recorded in the national Cattle Movement Monitoring System (CMMS). Culling refers to the exit of cows from the national herd, as a result of death but regardless of reason, and cow-culling rate was calculated as the number of cow exits (as defined above) each year divided by the number of calf births in the same year. Culling rate was determined by type (dairy or beef), date of birth, method of exit (slaughter or on-farm death), month of exit and interval between last calving and exit. The average cow-culling rate during 2003 to 2006 was 19.6% (21.3% for dairy, 18% for beef). While comparisons must be treated with caution, it concluded that the overall rates of culling in Ireland fell within published internationally accepted norms. The on-farm mortality rate of 3.2-4.1% was similar to that reported in comparable studies.
doi:10.1186/2046-0481-61-7-455
PMCID: PMC3113867  PMID: 21851717
abattoir slaughter; CMMS; cull cow; national herd turnover rate; on-farm-death; population balance
9.  Relationships between type and longevity in the Holstein breed 
The relationship between type traits and longevity was studied in the French Holstein breed using a survival analysis model. In this model, the phenotypic value adjusted for systematic fixed effects, the estimated breeding value, or the residual value (defined as the difference between the adjusted phenotypic value and the estimated breeding value) of the cow for each type trait was included as a risk factor. This was done separately for two subpopulations (registered and nonregistered herds) and with or without adjustment for production traits, i.e., considering true or functional longevity. For both types of herds, udder traits (and above all, udder depth) clearly influenced the length of productive life. There seemed to be a more pronounced voluntary culling on type traits in registered herds. The correction for the within herd-year class of production traits, as a way to approximate functional longevity, increased the importance of udder traits and decreased the weight of capacity traits. The same results were obtained when the phenotypic value of the cow for type was replaced by her estimated breeding value, whereas residuals had little impact. The relationship between longevity and type traits was most often nonlinear, in particular for udder traits, but in this study, no trait with a clear intermediate optimum was found.
doi:10.1186/1297-9686-33-1-39
PMCID: PMC2705382  PMID: 11268313
longevity; type traits; survival analysis; nonlinearity; dairy cattle
10.  Low reproductive performance and high sow mortality in a pig breeding herd: a case study 
Irish Veterinary Journal  2008;61(12):818-826.
Sow performance is a key component of the productivity of commercial pig farms. Reproductive failure in the sow is common in pig production. For every 100 sows served, 89 should farrow. In absence of specific diseases such as porcine parvovirus, pseudo-rabies, swine fever, leptospirosis and brucellosis, management failures are the most important causes of loss. A syndrome associated with reproductive inefficiency, and post-service vaginal discharge and high sow mortality in a commercial pig farm is described. Pregnancy failures exceeded 20% and sow mortality exceeded 12% for two consecutive years. The abnormal post-service vaginal discharge rate was 1.7% during the period of investigation.
An investigation involving an analysis of farm records, a review of breeding management practices, clinical examinations, laboratory analysis and examination of urogenital organs was conducted.
The main contributing factors found were a sub-optimal gilt breeding management, an inadequate culling policy in combination with a sub-optimal culling rate and the presence of cystitis in more than 1% of the urogenital organs examined. The high sow mortality rate was related to an aged breeding herd.
A control programme was recommended based on management changes involving oestrus detection, movement of gilts post-service, hygiene in the service area, boar exposure post-service and urinary acidification. This programme failed to increase the farrowing rate due to incomplete implementation of the recommendations made. The farrowing rate increased to 86.5% subsequent to a farm manager change in January 2005, which resulted in complete implementation of the control programme.
doi:10.1186/2046-0481-61-12-818
PMCID: PMC3113876  PMID: 21851706
cystitis; farrowing rate; sow; vulval discharge
11.  Association analysis between variants in KISS1 gene and litter size in goats 
BMC Genetics  2013;14:63.
Background
Kisspeptins are the peptide products of KISS1 gene, which operate via the G - protein-coupled receptor GPR54. These peptides have emerged as essential upstream regulators of neurons secreting gonadotropin-releasing hormone (GnRH), the major hypothalamic node for the stimulatory control of the hypothalamic–pituitary– gonadal (HPG) axis. The present study detected the polymorphisms of caprine KISS1 gene in three goat breeds and investigated the associations between these genetic markers and litter size.
Results
Three goat breeds (n = 680) were used to detect single nucleotide polymorphisms (SNPs) in the coding regions with their intron–exon boundaries and the proximal flanking regions of KISS1 gene by DNA sequencing and PCR–RFLP. Eleven novel SNPs (g.384G>A, g.1147T>C, g.1417G>A, g.1428_1429delG, g.2124C>T, g.2270C>T, g.2489T>C, g.2510G>A, g.2540C>T, g.3864_3865delCA and g.3885_3886insACCCC) were identified. It was shown that Xinong Saanen and Guanzhong goat breeds were in Hardy-Weinberg disequilibrium at g.384G>A locus (P < 0.05). Both g.2510G>A and g.2540C>T loci were closely linked in Xinong Saanen (SN), Guanzhong (GZ) and Boer (BG) goat breeds (r2 > 0.33). The g.384G>A, g.2489T>C, g.2510G>A and g.2540C>T SNPs were associated with litter size (P<0.05). Individuals with AATTAATT combinative genotype of SN breed (SC) and TTAATT combinative genotype of BG breed (BC) had higher litter size than those with other combinative genotypes in average parity. The results extend the spectrum of genetic variation of the caprine KISS1 gene, which might contribute to goat genetic resources and breeding.
Conclusions
This study explored the genetic polymorphism of KISS1 gene, and indicated that four SNPs may play an important role in litter size. Their genetic mechanism of reproduction in goat breeds should be further investigated. The female goats with SC1 (AATTAATT) and BC7 (TTAATT) had higher litter size than those with other combinative genotypes in average parity and could be used for the development of new breeds of prolific goats. Further research on a large number of animals is required to confirm the link with increased prolificacy in goats.
doi:10.1186/1471-2156-14-63
PMCID: PMC3734198  PMID: 23915023
Combinative genotype; SNP; PCR-RFLP; Candidate gene
12.  Sow wastage: reasons for and effect on productivity. 
The purpose of this study was to examine the reasons for, the rate and the effect of sow culling on productivity. Sow removal or wastage was investigated by means of producer questionnaires and by detailed production data recorded on 30 swine farms for two years. The sow removal rate was high (mean = 44.2%) with a wide herd-to-herd variation (range = 16% to 100%), and correlated negatively with litter size. Reproductive failure was the most common cause of culling cited by producers. It was concluded that sows on many Ontario farms were being culled prior to reaching their reproductive potential.
PMCID: PMC1255191  PMID: 3756675
13.  Effects of Oils Rich in Linoleic and α-Linolenic Acids on Fatty Acid Profile and Gene Expression in Goat Meat 
Nutrients  2014;6(9):3913-3928.
Alteration of the lipid content and fatty acid (FA) composition of foods can result in a healthier product. The aim of this study was to determine the effect of flaxseed oil or sunflower oil in the goat diet on fatty acid composition of muscle and expression of lipogenic genes in the semitendinosus (ST) muscle. Twenty-one entire male Boer kid goats were fed diets containing different levels of linoleic acid (LA) and α-linolenic acid (LNA) for 100 days. Inclusion of flaxseed oil increased (p < 0.05) the α-linolenic acid (C18:3n-3) concentration in the ST muscle. The diet high in α-linolenic acid (p < 0.05) decreased the arachidonic acid (C20:4n-6) and conjugated linolenic acid (CLA) c-9 t-11 content in the ST muscle. There was a significant (p < 0.05) upregulation of PPARα and PPARγ gene expression and downregulation of stearoyl-CoA desaturase (SCD) gene in the ST muscle for the high α-linolenic acid group compared with the low α-linolenic acid group. The results of the present study show that flaxseed oil as a source of α-linolenic acid can be incorporated into the diets of goats to enrich goat meat with n-3 fatty acids, upregulate the PPARα and PPARγ, and downregulate the SCD gene expression.
doi:10.3390/nu6093913
PMCID: PMC4179195  PMID: 25255382
flaxseed oil; omega-3 fatty acid; gene expression; lipogenic genes; goat meat
14.  Boar culling in swine breeding herds in Minnesota 
The Canadian Veterinary Journal  1990;31(8):581-583.
This investigation was conducted to study boar culling patterns in swine breeding herds. Data were obtained from 84 swine breeding herds and included 440 boars that were culled. Each producer was involved for 12 consecutive months, and recorded every boar that was removed from the herd, the date, and the reason for culling. The annual culling rate for the 84 farms averaged 59.4% ± 6.4 (SEM). The correlation coefficient between boar and sow culling was 0.52 (p <0.0001). Removal was the result of being overweight (47%), reproductive problems (18%), leg problems (12%), death (7%), and other diseases (4%). From the annual culling rate, the average breeding life of boars was estimated at 20 months. From this study, we concluded that the annual culling rate for boars in commercial herds was high and related to several different factors.
PMCID: PMC1480838  PMID: 17423646
15.  Gastrointestinal nematodes and anthelmintic resistance in Danish goat herds☆  
Parasite  2014;21:37.
The prevalence of gastrointestinal parasites in Danish goats and the presence of anthelmintic resistance (AR) in 10 selected herds were investigated during April–September 2012. All Danish herds (n = 137) with 10 or more adult goats were invited to participate, and of these 27 herds met the inclusion criterion of more than 10 young kids never treated with anthelmintics. Questionnaire data on management were collected, and faecal samples from 252 kids were analysed by the McMaster technique. From all herds with a mean faecal egg count (FEC) above 300 eggs per g of faeces, pooled samples were stained with peanut agglutinin (PNA) for specific detection of Haemonchus contortus. Strongyle eggs were detected with an individual prevalence of 69%, including Nematodirus battus (3.6%) and other Nematodirus species (15.0%). Eimeria spp. were observed in 99.6% of the kids. H. contortus was found in 11 of 12 (92%) tested herds. Anthelmintics were used in 89% of the herds with mean treatment frequencies of 0.96 and 0.89 treatments per year for kids and adults, respectively. In 2011, new animals were introduced into 44% of the herds of which 25% practised quarantine anthelmintic treatments. In 10 herds the presence of AR was analysed by egg hatch assay and FEC reduction tests using ivermectin (0.3 mg/kg) or fenbendazole (10.0 mg/kg). AR against both fenbendazole and ivermectin was detected in seven herds; AR against fenbendazole in one herd, and AR against ivermectin in another herd. In conclusion, resistance to the most commonly used anthelmintics is widespread in larger goat herds throughout Denmark.
doi:10.1051/parasite/2014038
PMCID: PMC4115478  PMID: 25076056
Goat; Parasites; Nematode; Parasite control; Herd management; Anthelmintic resistance
16.  Advancing parity is associated with high milk production at the cost of body condition and increased periparturient disorders in dairy herds 
Journal of Veterinary Science  2006;7(2):161-166.
The objectives of this study were to determine the effects of parity on milk production, body condition change, periparturient health, and culling in Korean dairy herds. The data utilized included; milk yield, body condition score, cow parity, calving condition, periparturient disorders, culling, and reproductive status, which were recorded from 1290 calvings in eight dairy herds. The mean milk yield in cows over 305 days increased with increasing parity (p < 0.01). Cows with parities of 3, 4, and 5 or higher lost more body condition than those with a parity of 1 during month 1 of lactation (p < 0.01), and body condition recovery by cows with parities of 4 and 5 or higher was slower (p < 0.01) than recovery by cows with parities of 1, 2, or 3 until month 3 of lactation. The risk of retained placenta, metabolic disorder, and endometritis also increased with advancing parity (p < 0.05). Moreover, the incidence of ovarian cysts was lower in cows with a parity of one than in cows with greater parities (p < 0.01). Culling rate due to reproductive failure also increased with advancing parity (p < 0.01). These results suggest that parity increases milk yield, body condition loss during early lactation, the risk of periparturient disorders, and culling due to reproductive failure in dairy herds.
doi:10.4142/jvs.2006.7.2.161
PMCID: PMC3242109  PMID: 16645342
body condition; culling; milk yield; parity; peritparturient disorder
17.  Direct and indirect effects of Johne's disease on farm and animal productivity in an Irish dairy herd 
Irish Veterinary Journal  2009;62(8):526-532.
Johne's disease (JD) is caused by infection with the organism Mycobacterium avium spp. paratuberculosis, leading to chronic diarrhoea and ill thrift in adult cattle. JD is considered to adversely affect farm performance and profitability. This retrospective case study was undertaken on a single commercial dairy herd in the south west of Ireland. Animal production records were interrogated to assess the effect of JD on milk yield (total kg per lactation), somatic cell count (the geometric mean over the lactation), reasons for culling, cull price and changes in herd parity structure over time. JD groups were defined using clinical signs and test results. One control animal was matched to each case animal on parity number and year. Specific lactations (clinical, pre-clinical and test-positive only) from 1994 to 2004 were compared between JD case and control cows. A significantly lower milk yield (1259.3 kg/lactation) was noted from cows with clinical JD in comparison to their matched control group. Clinical animals had an average cull price of €516 less than animals culled without signs of clinical disease. In contrast, little effect was noted for sub-clinical infections. These direct effects of JD infections, in combination with increased culling for infertility and increasing replacement rates, had a negative impact on farm production. Results from this study provide preliminary information regarding the effects of JD status on both herd and animal-level performance in Ireland.
doi:10.1186/2046-0481-62-8-526
PMCID: PMC3113779  PMID: 21851739
clinical symtoms; culling; dairy cows; disease impacts; Johne's Disease; milk yield
18.  Factors Associated with Mastitis in Ontario Dairy Herds: A Case Control Study 
Data from Ontario dairy cattle herds which had had a high average milk gel index for 1978 (cases) and from other herds which had had a low average during the same period (controls) were collected and analyzed using case control techniques. The purpose of the study was to contrast factors of husbandry and management between the two groups and to determine the relative contribution of each of these factors on mastitis (as determined indirectly by the milk gel index) at the herd level.
Control herds had higher average production levels than did case herds, shipping 1807 litres more milk per cow per year. Milk from control herds averaged 0.06 percentage points higher in butterfat, 0.19 percentage points higher in lactose and 0.05 percentage points lower in total protein. However, many factors can influence production, therefore these latter differences, in both shipped milk and composition, can not be attributed solely to differences in the prevalence of mastitis between the two groups.
Control herds were more likely to use teat dip, receive regular veterinary service, use dry cow antibiotic preparations and have knowledge concerning subclinical mastitis than were case herds. Control herds also tended to raise more of their own replacements, have a higher culling rate for reasons of low production and have a more modernized dairy operation. Case herds, on the other hand, were more likely to scrutinize foremilk, use more milking units per operator and wait longer between the start of stimulation and attachment of the milking unit.
The study confirms, under natural field conditions, the importance of integrated mastitis control practices and also reaffirms the relative importance of practices such as the use of teat dips and dry cow antibiotic preparations.
PMCID: PMC1320089  PMID: 7448625
19.  Prevalence of lameness and claw lesions during different stages in the reproductive cycle of sows and the impact on reproduction results 
Animal  2013;7(7):1174-1181.
Lameness in sows is an emerging disease condition with major effects on animal welfare and economics. Yet the direct impact on reproduction results remains unclear. The present field study investigated the impact of lameness and claw lesions throughout the reproductive cycle on (re)production results of sows. In five farms, a total of 491 group-housed sows were followed up for a period of one reproductive cycle. Sows were assessed for lameness every time they were moved to another area in the farm. Claw lesions were scored at the beginning and at the end of the cycle. Reproduction results included the number of live-born piglets, stillborn piglets, mummified fetuses and crushed piglets, weaning-to-oestrus interval and the presence of sows not showing oestrus post weaning, returning to service and aborting. Sows that left the group were recorded and the reason was noted. A mean prevalence of lameness of 5.9% was found, although it depended on the time in the productive cycle. The highest percentage of lame sows (8.1%) was found when sows were moved from the post-weaning to the gestation stable. No significant associations were found between lameness and reproduction parameters with the exception of the effect on mummified foetuses. Wall cracks, white line lesions, heel lesions and skin lesions did have an effect on farrowing performance. Of all sows, 22% left the group throughout the study, and almost half of these sows were removed from the farm. Lameness was the second most important reason for culling. Sows culled because of lameness were significantly younger compared with sows culled for other reasons (parity: 2.6 ± 1.3 v. 4.0 ± 1.8). In conclusion, the present results indicate that lameness mainly affects farm productivity indirectly through its effect on sow longevity, whereas claw lesions directly affect some reproductive parameters. The high percentage of lame sows in the insemination stable indicate that risk factor studies should not only focus on the gestation stable, but also on housing conditions in the insemination stable.
doi:10.1017/S1751731113000232
PMCID: PMC3666190  PMID: 23714359
sow; lameness; reproduction; culling; claw lesions
20.  Evaluating the fitness of human lysozyme transgenic dairy goats: growth and reproductive traits 
Transgenic Research  2010;19(6):977-986.
While there are many reports in the literature describing the attributes of specific applications of transgenic animals for agriculture, there are relatively few studies focusing on the fitness of the transgenic animals themselves. This work was designed to gather information on genetically modified food animals to determine if the presence of a transgene can impact general animal production traits. More specifically, we used a line of transgenic dairy goats expressing human lysozyme in their mammary gland to evaluate the reproductive fitness and growth and development of these animals compared to their non-transgenic counterparts and the impact of consuming a transgenic food product, lysozyme-containing milk. In males, none of the parameters of semen quality, including semen volume and concentration, total sperm per ejaculate, sperm morphology, viability and motility, were significantly different between transgenic bucks and non-transgenic full-sib controls. Likewise, transgenic females of this line did not significantly differ in the reproductive traits of gestation length and litter size compared to their non-transgenic counterparts. To evaluate growth, transgenic and non-transgenic kid goats received colostrum and milk from either transgenic or non-transgenic does from birth until weaning. Neither the presence of the transgene nor the consumption of milk from transgenic animals significantly affected birth weight, weaning weight, overall gain and post-wean gain. These results indicate that the analyzed reproductive and growth traits were not regularly or substantially impacted by the presence or expression of the transgene. The evaluation of these general parameters is an important aspect of defining the safety of applying transgenic technology to animal agriculture.
doi:10.1007/s11248-010-9371-z
PMCID: PMC2970820  PMID: 20135222
Reproduction; Growth; Transgenic; Goats; Lysozyme; Welfare
21.  Risk factors associated with cystic ovarian disease in Norwegian dairy cattle 
Background
The aims of this study were to establish the incidence of cystic ovarian disease (COD) and its geographical and seasonal variation in Norway, investigate the effect of COD on culling rates, and describe the effects of COD on subsequent reproductive performance and its association to twins.
Methods
Diagnosis of COD was made by veterinary surgeons in the field. Four statistical models were made all including herd as random effect: The four different dependent variables investigated were: 1) Diagnosis of COD between 40 and 165 days in milk or not; (n = 511,657); 2) Twins or singleton; data restricted to lactations with new calving (n = 156,661): 3) Culling/removal or not (n = 573,184): 4) Culling due to reproductive problems; data included only lactations which ended in culling (n = 234,232). Model 1, 3 and 4 applied Cox regression models, and model 2 logistic regression. Independent variables were parity, twins/singletons, calving season, herd size, region, COD occurrence in present lactation (if not dependent), and COD diagnosis in previous lactation.
Results
The incidence was 0.82% per lactation. COD increased with increasing parity, was smallest at herd size between 35 and 85 cows. Cows in 1st parity and calved in spring had lowest hazard of COD and hazard for COD diagnosis was highest in autumn with HR = 2.6 (1.9 - 3.4) compared to spring. There was an interaction between parity and season. COD incidence was lower south of 60°N. Cows which experienced COD had an increased odds of giving birth to twins OR = 2.2 (1.7 - 2.7). Of those that were culled, those with COD were culled more frequently because of reproductive problems; HR = 2.1 (1.9 - 2.3) for higher parity than 2. Having COD diagnosed in the preceding lactation was a hazard for diagnosis in the lactation studied.
Conclusion
COD diagnosis is strongly associated with season (autumn calving) and parity. Herds north of 60°N have more COD. Occurrence of COD is associated with twin births as well as culling due to reproduction.
doi:10.1186/1751-0147-52-60
PMCID: PMC2990741  PMID: 21059258
22.  The Effects of Prenatal Stocking Densities on the Fear Responses and Sociality of Goat (Capra hircus) Kids 
PLoS ONE  2014;9(4):e94253.
Prenatal stress (stress experienced by a pregnant mother) and its effects on offspring have been comprehensively studied but relatively little research has been done on how prenatal social stress affects farm animals such as goats. Here, we use the operational description of ‘stress’ as “physical or perceived threats to homeostasis.” The aim of this study was to investigate the prenatal effects of different herd densities on the fear responses and sociality of goat kids. Pregnant Norwegian dairy goats were exposed to high, medium or low prenatal animal density treatments throughout gestation (1.0, 2.0 or 3.0 m2 per animal, respectively). One kid per litter was subjected to two behavioral tests at 5 weeks of age. The ‘social test’ was applied to assess the fear responses, sociality and social recognition skills when presented with a familiar and unfamiliar kid and the ‘separation test’ assessed the behavioral coping skills when isolated. The results indicate goat kids from the highest prenatal density of 1.0 m2 were more fearful than the kids from the lower prenatal densities (i.e. made more escape attempts (separation test: P < 0.001) and vocalizations (social test: P < 0.001; separation test: P < 0.001). This effect was more pronounced in females than males in the high density (vocalizations; social test: P < 0.001; separation test: P  =  0.001) and females were generally more social than males. However, goat kids did not differentiate between a familiar and an unfamiliar kid at 5 weeks of age and sociality was not affected by the prenatal density treatment. We conclude that high animal densities during pregnancy in goats produce offspring that have a higher level of fear, particularly in females. Behavioral changes in offspring that occur as an effect of prenatal stress are of high importance as many of the females are recruited to the breeding stock of dairy goats.
doi:10.1371/journal.pone.0094253
PMCID: PMC3978004  PMID: 24710177
23.  Measures of herd health and productivity in Ontario cow-calf herds 
The Canadian Veterinary Journal  1991;32(7):413-420.
A cohort of cows and heifers in 180 separate breeding herds from 170 randomly sampled farms was followed from the 1986 breeding season through to the weaning of their calves in 1987. Data were collected from farm records, survey information collected during farm visits, and provincial government weaning-weight records.
“Kilograms of calf weaned per female-exposed-to-breeding” was calculated as a summary measure of herd productivity. The lowest 25% of cow-herds produced less than 160 kg of calf weaned per cow-exposed-to-breeding, while the highest 25% exceeded 205 kg.
Overall calf crop was 78.1% for cows and 78.5% for heifers. The 25th, 50th, 75th, and 90th percentile estimates for rates, which were components of calf crop (e.g. calving rate), were estimated. The component rates that most influenced calf crop were culling rate for cows and stillbirth rate for heifers.
PMCID: PMC1480990  PMID: 17423818
24.  Mother goats do not forget their kids’ calls 
Parent–offspring recognition is crucial for offspring survival. At long distances, this recognition is mainly based on vocalizations. Because of maturation-related changes to the structure of vocalizations, parents have to learn successive call versions produced by their offspring throughout ontogeny in order to maintain recognition. However, because of the difficulties involved in following the same individuals over years, it is not clear how long this vocal memory persists. Here, we investigated long-term vocal recognition in goats. We tested responses of mothers to their kids’ calls 7–13 months after weaning. We then compared mothers’ responses to calls of their previous kids with their responses to the same calls at five weeks postpartum. Subjects tended to respond more to their own kids at five weeks postpartum than 11–17 months later, but displayed stronger responses to their previous kids than to familiar kids from other females. Acoustic analyses showed that it is unlikely that mothers were responding to their previous kids simply because they confounded them with the new kids they were currently nursing. Therefore, our results provide evidence for strong, long-term vocal memory capacity in goats. The persistence of offspring vocal recognition beyond weaning could have important roles in kin social relationships and inbreeding avoidance.
doi:10.1098/rspb.2012.0986
PMCID: PMC3415910  PMID: 22719031
Capra hircus; individual recognition; long-term memory; mammal; vocal communication
25.  Culling practices of Ontario cow-calf producers. 
This study describes the distribution of herd culling rates for 123 Ontario cow-calf herds maintaining individual animal records. Associations between culling and factors at both the individual and herd level were examined. In addition, the relative importance of individual animal and herd level influences on culling were investigated. The following individual cow culling risk factors: nonpregnancy, age, weaning weight index, calf outcome, abortion, prolapsed vagina, prolapsed uterus, calving injury, lameness and mastitis or udder problems were significantly associated with culling (p less than 0.01). Two herd level factors were associated with increased culling rates: a higher than average proportion of heifers and a shorter than average calving season (p less than 0.01). The proportion of culling variation attributed to individual animal and herd level influences varied with model type. While simple models (one-way ANOVA) indicated that the herd variance component for culling was relatively minor, more complex models indicated larger herd-to-herd variability (mixed model ANOVA). Thus, it appeared that the probability of culling for a cow with a given set of risk factors depended to an important extent on manager decisions in the herd of origin.
PMCID: PMC1263503  PMID: 1586894

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