Single Calves Research Articles

232 Evaluation of a phytogenic feed additive with essential oils and plant extracts on growth performance in single sourced steer calves fed a forage-based diet during the initial 53 d receiving period

Abstract The receiving period of a feedlot calf is one of the most stressful stages in the life of that animal and can result in respiratory disease caused, in part, by reduced feed intake and transit stress. Feeding a phytomolecule compound in combination with current therapeutic strategies may aid in controlling systemic inflammation and improve the performance of newly received calves. This study determined whether a phytogenic feed additive with essential oils and plant extracts (PFA) influences measures of growth and growth efficiency during the feedlot receiving phase. The two treatments were a control group fed no additive (CON) and a treatment group fed PFA additive at a rate of 0.25 g/45.4 kg of body weight (BW; PFA). Steers were transported 285 km from an auction facility to the Ruminant Nutrition Center in Brookings, SD where they were vaccinated against viral respiratory diseases and clostridial species, and administered pour-on anthelmintic. Steers were divided into 10 replicate pens of 8 steers (305 ± 30 kg) per treatment (n = 160 steers) in a randomized complete block design. The steers were fed a basal diet [dry matter (DM) basis] containing corn silage (74%), DDGS (21%), a liquid supplement (5%), and monensin sodium (Rumensin-90, Elanco Animal Health) at 25 g/907 kg (DM basis) for 53 d. Steers were fed 2X daily with intakes closely managed for the first 14 d during adaptation to the receiving diet then a slick bunk management strategy was applied for the remainder of the study. No mortality was observed in this study, and one steer was treated for respiratory disease from the CON group. There were no significant differences observed in BW, average daily gain (ADG), variation in ADG, dry matter intake, or feed conversion efficiency from d 1 to 29, 29 to 53, or during the cumulative receiving period (P ≥ 0.11) between the CON and PFA groups. NEm and NEg did not differ between the treatments (P ≥ 0.79). The ratio of observed-to-expected dietary net energy was also not affected by dietary treatment (P ≥ 0.71). The steers used in this study were in good health and had minimal morbidity (0.63%) with no mortality during the 53-d receiving study which contributed to the feed additive having no appreciable influence on the growth and health outcomes in this study.

Retained placenta in dairy cows living in an all-day cowshed rearing system

This study aimed to determine the prevalence and factors that influence the incidence of retained placenta in dairy cows reared under an all-day cowshed housing system at KUD Tani Wilis, Sendang District, Tulungagung. This study used 216 dairy cows, that had already calved, that had been identified to have medical and reproductive records for data exploration. Data collected included the sex and weight of calf, single or twin calves, age of the dam, cowshed structure (floor, puddles on the floor, gutter, distance of cowshed to waste disposal, type of floor and roof, and sunlight exposure), feed of the dam (forage, concentrate, mineral supplements), frequency of retained placenta cases on calving intervals and days open of the dams. The prevalence of retained placenta was presented descriptively. Factors related to the retained placenta and its effect on calving interval and days open were analyzed by Chi-square test using Statistical Product and Service Solution (SPSS) software version 20 for Windows. The result showed that the prevalence rate of retained placenta was 19.91% of all dairy cow populations in the district. Furthermore, the sex of the calf, age of the dam, sunlight exposure, and the quantity of feed (forage and concentrate) were related to the retained placenta (p <0.05). In addition, retained placenta increased along with extending of days open and calving interval. It could be concluded that the factors that influenced the prevalence of retained placenta were the sex of the calf, the age of the cow, the feed and concentrate, and the cowshed that is not facing the sun.

Retained placenta in dairy cows living in an all-day cowshed rearing system

This study aimed to determine the prevalence and factors that influence the incidence of retained placenta in dairy cows reared under an all-day cowshed housing system at KUD Tani Wilis, Sendang District, Tulungagung. This study used 216 dairy cows, that had already calved, that had been identified to have medical and reproductive records for data exploration. Data collected included the sex and weight of calf, single or twin calves, age of the dam, cowshed structure (floor, puddles on the floor, gutter, distance of cowshed to waste disposal, type of floor and roof, and sunlight exposure), feed of the dam (forage, concentrate, mineral supplements), frequency of retained placenta cases on calving intervals and days open of the dams. The prevalence of retained placenta was presented descriptively. Factors related to the retained placenta and its effect on calving interval and days open were analyzed by Chi-square test using Statistical Product and Service Solution (SPSS) software version 20 for Windows. The result showed that the prevalence rate of retained placenta was 19.91% of all dairy cow populations in the district. Furthermore, the sex of the calf, age of the dam, sunlight exposure, and the quantity of feed (forage and concentrate) were related to the retained placenta (p <0.05). In addition, retained placenta increased along with extending of days open and calving interval. It could be concluded that the factors that influenced the prevalence of retained placenta were the sex of the calf, the age of the cow, the feed and concentrate, and the cowshed that is not facing the sun.

Production cow-calf responses from perennial forage-based and integrated beef-cropping systems.

An experiment was conducted to measure production responses of an alternative cow-calf production system integrated into a cropping system without access to perennial forage compared to a traditional cow-calf system utilizing perennial forage. Multiparous, cross-bred beef cows (n = 160; average age = 6.2 ± 2.8 yr) were utilized in a randomized complete block experimental design and unstructured treatment design. Upon initiation, cows were blocked by age and stratified by source, assigned randomly to one of two production systems, each with four replicates (n = 20 cows/replicate). Once allotted to their treatment groups, cows remained in their experimental units for the duration of the experiment. Treatments were: 1) a traditional system consisting of April to May calving with smooth bromegrass pasture and grazed corn residue as forage resources (TRAD); 2) an alternative system consisting of July to August calving utilizing partial-drylot feeding, summer-planted oats, and corn residue grazing (ALT). There were no differences (P ≥ 0.27) in calving rates (91.8 vs. 86.7 ± 2.92%), pregnancy rates (89.3 vs. 89.9 ± 2.66%), and weaning rates (87.2 vs. 82.3 ± 3.29%) for TRAD vs. ALT, respectively. However, there was an increase (P = 0.04) in the rate of twin offspring in ALT (2.9 vs. 9.4 ± 2.36% for TRAD vs. ALT, respectively). One calf from the set of twins was selected randomly at birth to be removed from the experiment, so the production data are only from single calves. There was no difference (P = 0.47) in calf body weight at birth (40 vs. 39 ± 0.7 kg for TRAD vs. ALT, respectively). At weaning, calves in the ALT system were lighter (P < 0.01) at the same day of age (184 vs. 229 ± 5.5 kg) compared to TRAD calves. Cows from the ALT system had fewer (P < 0.01) kg weaned per cow exposed to bull (150 vs. 199 ± 7.2 kg) compared to TRAD cows. Apart from the twinning rate, no differences in reproductive performance were observed among systems. However, reduced weaning weights and kilogram of weaned calf per cow exposed may negatively impact revenue to the cow-calf enterprise of the ALT system.

Changes in Fecal Carriage of Extended-Spectrum β-Lactamase Producing Enterobacterales in Dutch Veal Calves by Clonal Spread of Klebsiella pneumoniae.

This study aimed to characterize the changes in fecal carriage of Extended-Spectrum β-Lactamase (ESBL) producing Enterobacterales (ESBL-PE) in a single Dutch veal calves. During the rearing period at the Dutch veal farm, a decrease in fecal carriage of cefotaxime-resistant Escherichia coli isolates was observed after 2 weeks at the veal farm, while an increase of cefotaxime-resistant Klebsiella pneumoniae isolates was demonstrated. E. coli and K. pneumoniae were isolated from rectal swabs collected from 110 veal calves in week 2, 6, 10, 18, and 24 after their arrival at the farm. ESBL-PE isolates were selectively cultured and identified by MALDI-TOF. ESBL genes were characterized by RT-PCR, PCRs, and amplicon sequencing. A total of 80 E. coli and 174 K. pneumoniae strains were isolated from 104 out of 110 veal calves. The prevalence of ESBL-E. coli decreased from week 2 (61%) to week 6 (7%), while an unexpected increase in ESBL-K. pneumoniae colonization was detected in week 6 (80%). The predominant ESBL genes detected in E. coli isolates were blaCTX-M-15 and the non-ESBL gene blaTEM-1a, while in K. pneumoniae blaCTX-M-14 gene was detected in all isolates. Four cefotaxime-resistant K. pneumoniae isolates were randomly selected and characterized in deep by transformation, PCR-based replicon typing, and whole-genome sequencing (WGS). The clonal relatedness of a subgroup of nine animals carrying K. pneumoniae ESBL genes was investigated by Multi Locus sequence typing (MLST). In four ESBL-K. pneumoniae isolates, blaCTX-M-14 was located on IncFIIK and IncFIINK plasmid replicons and the isolates were multi-drug resistant (MDR). MLST demonstrated a clonal spread of ESBL-K. pneumoniae ST107. To the best of our knowledge, this is the first study to report a change in fecal carriage of ESBL-PE over time in the same veal calf during the rearing period.

90 Comparing Methods of Raising Twin Beef Calves

Abstract Twinning has shown promise as a means of increasing reproductive efficiency in beef cattle. The objective of this study was to compare the performance of 1) twin calves raised by their dam (twin born-twin raised; TT); 2) twin calves where one calf was grafted to another cow that lost her calf and one calf was left with their dam (twin born-single raised; TS); and 3) single born calves that were raised by their dams (single born-single raised; S). To achieve twinning, sixty-three Angus-cross cows were estrus synchronized and artificially inseminated. Seven days later, an embryo was placed into the uterine horn contralateral to the corpus luteum. Fourteen twin pairs and 11 singleton calves were produced from the described technique. Three natural twin pairs were added to the study. Birth order was recorded for twin calves (1=first calf; 2=second calf). Birth weights (BW) and blood samples for measuring serum total protein, IgG1, and IgM were collected 24 h post-calving. Calves were weighed at approximately six months of age, and a 200-d adjusted weight was calculated using the following equation: [(ADG x 200 d) + BW=A200dW]. Calf behavior data collected included interval to standing and first nursing, duration of dam nursing, and duration of non-dam nursing. Single calves had greater (P &amp;lt; 0.001) BW compared to TT and TS. Adjusted 200-d weights were greater (P &amp;lt; 0.05) for S compared to TS. There was a positive correlation between BW and A200dW (r=.32; P &amp;lt; 0.05). Behavior data did not differ among raising methods. Twin-single calves had lower (P &amp;lt; 0.05) serum IgG1 concentrations compared to S calves. Twin-Twin calves had a combined A200dW of 185 kg more than single born-single raised calves.

A method of outdoor housing dairy calves in pairs using individual calf hutches

Interest in housing dairy calves in groups is currently growing. Group housing using individual calf hutches, a resource already available in most dairy farms in North America, could provide a novel housing method that can be a simple way to implement group housing on farm. The main objective of this study was to determine whether pair housing dairy calves in hutches outdoors would result in similar weight gain and milk intake compared with individual housing in hutches. The study was designed to avoid competition for resources (including milk and solid feed, teat, bucket, outdoor space, and hutch) to test a setup that has the potential to maximize performance and calf growth. Secondary objectives were to document how calves in both treatments use their environment in terms of time spent and behaviors performed in each area, how paired calves interact, and the time they spend together. Single calves (n = 6/season) were housed in 1 hutch with an attached outdoor environment; paired calves (n = 6 pairs/season) were given twice the resources. Calves were fed up to 16 L/d of milk replacer. Daily milk intake and weekly weight gains were recorded. Behavioral observations were recorded live once per week for 5 (summer) or 4 (winter) nonconsecutive periods. Paired and single calves had similar weight gain (averaging from 1.1 to 1.3 kg/d across trials) and milk intake (averaging from 11.1 to 13.7 kg/d across trials), showing no difference in performance between treatments. Low occurrences of cross sucking (averaging from 0.1 to 0.4 bouts/h of observation per pen across trials) and displacements at the teat (0.8 to 1.4 bouts/h of observation per pen across trials) were found. All calves altered their behavior in some way to accommodate companions; paired calves were seen interacting and spending time together (i.e., lying in the same hutch), and in the summer trial single calves spent less time lying inside the hutch than paired calves, presumably to have visual access to other calves. The solution of mixed indoor and outdoor housing environments tested as part of this study showed that calves make use of all spaces provided to them in winter and in summer conditions while maintaining good performance. Housing calves in pairs using individual hutches can be a suitable alternative to housing calves individually in hutches outdoors.

Gonadal hormones level and morphometric traits in cow deliveres twin and single calves

The objectives of study were to investigate follicle stimulating hormone (FSH) and luteinizing hormone (LH) level in four groups beef cow composed of Ongole Grade cow delivered twinning calves (OGT), Ongole Grade cow delivered single calf (OGS), Simmental crossbred cow delivered twinning calves (SCT) and Simmental crossbred cow delivered single calf (SCS). Morphometric traits included body weight, heart girth, body length, shoulder height, and abdominal circumference were taken from cows. Cows were reared by farmers in Grobogan and Kendal Regency, Central Java. Blood serums of cows were taken at estrus. FSH and LH concentration were measured with enzyme linked fluorescent assays (ELFA) technique.FSH and LH concentration were compared between OGT, OGS, SCT, and SCS. Result showed that there were no significant difference of FSH and LH concentration between OGT and OGS, between OGT and SCT, between OGT and SCS. There were no significant difference between OGS and SCT, and OGS and SCS. There were no significant difference between SCT and SCS. Low concentration of FSH and LH in all cows was related to suckle period, when prolactin concentration was inversely related to FSH and LH concentration.

The effect of age at separation from the dam and presence of social companions on play behavior and weight gain in dairy calves

Play behavior positively affects welfare of farm animals, yet impoverished social environment during early ontogeny may limit the opportunity or motivation to play. This study investigated the independent and the combined effects of the presence of the dam during the colostrum feeding period and subsequent group housing on play behavior and growth in dairy calves. 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 4d after birth and companion housing (single pens or grouped housing in pens of 4 calves between 1 and 8wk of age). After 8wk of age all calves were housed in groups of 4 calves. Play behavior of the calves was observed at 2, 5, and 12wk of age in the following situations: 6 h of spontaneous behavior in the home pen, a 15-min open-field test, and a 15-min social test with an unfamiliar calf. Additionally, play behavior after grouping or relocation at 8wk of age was recorded during two 2-h sessions. There were no significant effects of the mother by companion interaction either on the amount of play behavior in any of the tests or on the body weights of the calves. Presence of the mother after birth did not increase later playfulness, with the exception of higher spontaneous play at 12wk of age. When calves were housed in groups of 4, they played more in the home pen on wk 2 and 5 than individually housed calves of the same age. In contrast, individually housed calves were more playful during open-field tests and social tests on wk 2 and 5. At 8wk, single calves that were placed in a new pen with 3 unfamiliar calves played more than twice as much as grouped calves that were just moved to a new pen with familiar companions. These results show that single-housed calves are deprived of natural levels of play, as demonstrated by both their lower spontaneous play behavior and the higher rebound effect when they are exposed to larger spaces or larger spaces plus companions. Calves that stayed with their mothers for 4d postpartum grew much better until the end of the second week. After that, grouped calves grew better until wk 10 and they tended to be heavier for at least 2wk after relocation or mixing at wk 8. The study shows that brief maternal rearing and group housing independently improve different aspects of performance and welfare of dairy calves.

350 EFFECT OF DIFFERENT SUB-DOSES OF EQUINE CHORIONIC GONADOTROPIN ON PREGNANCY AND TWINNING RATES OF CYCLIC ZEBU COWS SUBMITTED TO FIXED-TIME ARTIFICIAL INSEMINATION

The injection of a low dose of eCG has the potential to induce multiple ovulation and pregnancies in cattle. The present study aimed to evaluate the ovarian response, conception rate and incidence of twin pregnancies of cyclic cows receiving 1 of 2 low doses of eCG. Multiparous Nellore (Bos t. indicus) cows with plasma progesterone levels &gt;1 ng∙mL–1 on at least one of 2 blood samples collected at 10-day intervals (Day –10 and Day 0) received an intramuscular (IM) injection of 2 mg of oestradiol benzoate (EB; Estrogin®, AUSA, São Paulo, Brazil) and a vaginal device (DIP) containing 1 g of progesterone (Primer®, Tecnopec, São Paulo, SP, Brazil) on Day 0. On Day 8, the DIP was removed and cows received an IM injection of 150 μg of cloprostenol (Veteglan®, Hertape Calier, Juatuba, MG, Brazil). At this time, the animals were randomly distributed into 3 groups. Group 1 (n = 30) received an IM injection of 2 mL of saline, whereas groups 2 (n = 41) and 3 (n = 23) received 600 IU and 900 IU of eCG (Novormon® MSD Saude Animal, São Paulo, Brazil), respectively. Twenty-four hours later (Day 9), all groups received 1 mg of EB and were submitted to fixed-time artificial insemination (FTAI) 30 h later (i.e. 54 h after DIP removal). Oestrus observation was performed daily from the time of the withdrawal of the DIP until the day of FTAI. Ovaries were examined ultrasonically at the time of FTAI, the following day and 7 days after FTAI. Pregnancy diagnosis was done by ultrasonography 30 days after FTAI and the incidence of twin or single calves was recorded at birth. Data were analysed by chi-square test. The rate of expression of oestrus was 70.0% (group 1), 82.9% (group 2), and 78.2% (group 3; P = 0.25). Cows that had 2 or more large follicles at the time of FTAI was 0% (group 1), 14.6% (group 2), and 34.8% (group 3; P &lt; 0.05). The ovulation rate of cows in group 1 (80.0%) was higher than cows in groups 2 (48.8%) and 3 (52.2%; P &lt; 0.05). The conception rates for groups 1, 2, and 3 were 50.0, 26.8, and 39.1%, respectively (P &lt; 0.05). Two animals in group 3, one in group 2, and none of group 1 had twin pregnancies on Day 30 after FTAI. Only one of these cows (group 3) had a twin calving. It was concluded that the injection of 600 or 900 IU eCG, in an oestradiol/progestogen FTAI protocol does not result in an increase in the rate of twin calvings, but may negatively affect pregnancy rates of cyclic Nellore cows.Financial support was provided by FAPESP (proc. 2011/13096–0).

Factors affecting survival and cause-specific mortality of saiga calves in Mongolia

Factors affecting juvenile survival are poorly known in the world’s most northern antelope, the endangered saiga (Saiga tatarica), yet these factors are fundamental for understanding what drives population change. We monitored Mongolia saiga (S. tatarica mongolica) calves in Sharga Nature Reserve, western Mongolia, during 2008–2010. Our results showed that male and single calves were heavier than females and twins, respectively. However, we identified no significant differences in seasonal or annual survival rates between sexes or between singletons and twins. Litter size and birth mass varied among years, and there was a negative relationship between these variables. Survival of calves during the 1st year was best explained by the covariates of year and litter size (confounded with body mass), suggesting that interannual variation in environmental conditions influenced twinning rates and body mass, and might play a key role in 1st-year survival. We identified 3 sources of mortality—predation by raptors, foxes (red fox [Vulpes vulpes] and corsac fox [V. corsac]), and lynx (Lynx lynx). Most predation was attributed to raptors, such as golden eagles (Aquila chrysaetos) and cinereous vultures (Aegypius monachus). Our results point to both environmental and biotic factors affecting survival of juvenile saiga.

275 SEX-SELECTED MULTIPARITY: A MODEL-ASSISTED REPRODUCTIVE TECHNOLOGY FOR WILDLIFE CONSERVATION

The objective of this research was to evaluate the proportion of single and double births, including the sex of the offspring obtained, after the transfer of two IVF-produced embryos using sexed semen. Bos indicus cows (n = 25) under free-range grazing in the humid tropical zone of Mexico, with body condition scores from 2.6 to 3.6 on a scale of 1 to 9, were used as recipients. The cows were isolated from bulls for 50 days before synchronization and supplemented for 30 days before beginning the protocol with 2 kg of commercial feed with 18% protein, 80 g of mineral salts, and 40 mL of corn oil daily until pregnancy diagnosis. The feed, minerals, and vaccinations were the same for all cows. The following treatment was utilised: Day 0: application of an intravaginal device with 1.9 g of progesterone, 1 mg of oestradiol benzoate IM, and 7 mL of selenium-vitamins A, D, and E IM; Day 8: removal of the intravaginal device, 0.15 mg of prostaglandin F2α IM and 300 IU of eCG IM; and Day 9: 0.5 mg mL–1 IM of oestradiol benzoate. Day 10 was considered the day of oestrus. From Days 17 to 23, two fresh sexed semen IVF-derived embryos were transferred to the uterine horn ipsilateral to the corpus luteum. The embryos were produced using oocytes collected by aspiration of ovaries from B. indicus slaughtered cows and frozen–thawed sexed semen (X-chromosome bearing) from Bos taurus. The embryos were incubated until the blastocyst stage (7 days) and only Grade 1 embryos were used. Pregnancy was diagnosed by rectal palpation 60 days after embryo transfer. A 56.5% pregnancy rate (13/23) and a 47.8% parturition rate (11/23) were obtained. Of 11 parturitions, there were 7 twin and 4 single calves for a total of 18 calves, 16 females and 2 males. The twin-calf birth weight average was 30.4 kg, SD = 2.5 kg (range 26 to 33 kg) compared with the single-calf birth weight average of 35.8 kg, SD = 1.7 kg (range 34 to 38 kg). One should note that the protocol used herein, the good body condition of the cattle, the diet and hormones, the reproductive management, and application of assisted reproductive techniques used by experienced personnel are all factors likely influencing the increased pregnancy and calving rates while modifying the normal proportion of offspring sex. Freemartinism, which has also been found to occur in wildlife, was eliminated because all twin births were female, with only one instance of dystocia, which was subsequently resolved with minor assistance. The low occurrence of dystocia in the present study may be due to the smaller size of the F1 female calves. The ability to produce additional females using this method can be desirable for boosting a population faster, for example, with endangered species or even herd replacements for improved genetics. Further, in the deer industry, ranch owners may desire more twin male births for hunting purposes. Future work may apply the bovine model that we have presented herein for such endeavours.

Reproduction performance of cows with single, twin and triplet calves

The aim of this study was to analyse data on 74,081 calvings, subsequent lactation performance and culling of 23,588 Black-and-White cows improved with Holstein-Friesians. The animals represented the active population in Pomerania and Kujavia, first calved in 2000 and 2001, and were culled before the end of 2008. Frequency of calvings, which averaged 1.5% for twin births and just 0.02% for triplet births, increased with age of cow and also with increasing milk yield in the preceding lactation. Performance results showed that mothers of twins were superior to mothers of single calves in terms of milk yield (1.3 kg milk/day milking). Despite the greater perinatal mortality of twins and triplets, multiple pregnancies gave rise to a greater number of calves compared to single pregnancies. However, multiple pregnancies were accompanied by adverse effects such as increased proportion of complications requiring human assistance, mechanical assistance and veterinary intervention (1.2 × more). Fertility of the cows deteriorated after multiple pregnancies, with particularly unfavourable indicators of fertility found for triplet births, decreased chance of survival to the next calving, and increased culling rates in cows, especially due to udder diseases, infertility, reproductive diseases, old age, metabolic and gastrointestinal diseases, and locomotor system diseases. It was found that the increasing milk yield was paralleled by the increasing proportion of multiple pregnancies. This has highlighted the need for early and reliable diagnosis and management of twin pregnancies, which is supposed to facilitate parturition and ensure survival of calves.

Genetic change in the open reading frame of bovine viral diarrhea virus is introduced more rapidly during the establishment of a single persistent infection than from multiple acute infections

Bovine viral diarrhea viruses (BVDV) are ubiquitous viral pathogens of cattle with a high degree of sequence diversity amongst strains circulating in livestock herds. The driving force behind change in sequence is not well established but the inaccurate replication of the genomic RNA by a viral RNA polymerase without proof-reading capabilities as well as immune pressure on immunodominant proteins are thought to play major roles. Additionally, it is not clear when the majority of changes are introduced, whether during acute infections with exposure to innate and adaptive immune responses or in establishment of persistent infections (PI) in utero. To examine which generates greater sequence diversity, two groups of viruses were compared. The first was six isolates of a single strain of BVDV-2 that were isolated over greater than a year's time. These viruses caused a series of severe acute (SA) BVD outbreaks over a large geographic area. Changes in nucleotide sequence were determined by comparison of the sequence of each strain to the six virus consensus sequence. The second group was composed of six BVDV strains isolated from PI calves whose dams were exposed to PI cattle. Changes were identified by comparison of the sequence of the progenitor PI virus to that of the progeny viruses from the single in vivo ‘passage’. The open reading frames (ORF) of the six SA isolates were >99% identical at the nucleotide level with 30% of the changes being nonsynonymous changes. The amount of genetic change increased with time and distance from the original outbreak. Similarly, the PI viruses isolated from single passage PI calves had >99% identity with the progenitor virus. The number of nucleotide changes in these viruses was equal to or greater than that observed in the SA viruses. The majority of the nonsynonymous changes were found in the structural proteins, with 65% of these occurring in the immunodominant E2 protein. Antigenic mapping studies using a monoclonal antibody panel specific for the BVDV E2 protein showed no antigenic differences amongst the six SA viruses, nor between the progenitor and progeny type 1a and type 2 persistent viruses. However, antigenic differences were observed in the two type 1b progeny viruses that possessed the greatest number of amino acid changes. Two antibodies were found to have altered staining patterns. These results suggest that the establishment of a single persistent infection results in more rapid generation of genetic diversity in BVDV strains than a series of acute infections and may contribute to antigenic change in the absence of an immune response.

Molecular and epidemiological characterization of bovine intrauterine Escherichia coli

Escherichia coli are believed to be associated with postpartum metritis and endometritis but their role in the pathogenesis of both diseases is still undefined. In this study, uterine swabs for E. coli isolation were collected from 374 lactating Holstein cows housed on 4 commercial farms near Ithaca, New York. A total, 125 of 374 cows (33.4%) were positive for E. coli culture. Standard multiplex PCR protocols were used to screen the isolates for the presence of 32 virulence factor genes. Cows that had twin parturition were 4.4 times more likely to have intrauterine E. coli contamination than those that gave birth to single live female calves. Stillborn parturition and birth of single live male calves also increased the odds of intrauterine contamination by E. coli (3.7- and 1.6-fold, respectively) compared with birth of live female calves. Six virulence factors, common to extraintestinal and enteroaggregative E. coli, were found to be associated with metritis and endometritis: fimH, hlyA, cdt, kpsMII, ibeA, and astA. The virulence factor gene fimH was the most prevalent and the most significant: intrauterine E. coli carrying fimH and at least 1 of the other 5 identified virulence factors were pathogenic, and phylogenetic analysis based on the nucleotide sequence of DNA gyrase from 41 such IUEC revealed 2 clades.

Use of sexed semen and its effect on conception rate, calf sex, dystocia, and stillbirth of Holsteins in the United States

Use of sexed semen for artificial insemination of US Holstein heifers (1.3million breedings) and cows (10.8million breedings) in Dairy Herd Improvement herds was characterized by breeding year, parity, service number, region, herd size, and herd milk yield. Sexed semen was used for 1.4, 9.5, and 17.8% of all reported breedings for 2006, 2007, and 2008, respectively, for heifers, and for 0.1, 0.2, and 0.4%, respectively, for cows. For 2008 sexed semen breedings, 80.5 and 68.6% of use was for first services of heifers and cows, respectively. For cows, 63.1% of 2008 sexed semen use was for first parity. Mean sexed semen use within herd was the greatest for heifers in the Southwest (36.2%) and for cows in the Mideast (1.3%). Mean sexed semen use increased for heifers but changed little for cows as either herd size or herd mean milk yield increased. Availability of sexed semen was examined for Holstein bulls in active AI service; of 700 bulls born after 1993, 37% had sexed semen marketed by mid August 2009. Active AI bulls with marketed sexed semen were superior to average active AI bulls for evaluations of yield traits, productive life, somatic cell score, daughter pregnancy rate, service-sire calving ease, service-sire stillbirth, final score, sire conception rate, and lifetime net merit. The effect of sexed semen use on conception rate, calf sex, dystocia, and stillbirth also was examined for heifers and cows. Mean conception rate for heifers was 56% for conventional and 39% for sexed semen; corresponding conception rates for cows were 30 and 25%. For single births from sexed semen breedings, around 90% were female. Dystocia and stillbirth were more frequent for heifers (6.0 and 10.4%, respectively, for conventional semen; 4.3 and 11.3%, respectively, for sexed semen) than for cows (2.5 and 3.6%, respectively, for conventional semen; 0.9 and 2.7%, respectively, for sexed semen). Difficult births declined by 28% for heifers and 64% for cows with sexed semen use. Stillbirths were more prevalent for twin births except for sexed semen heifer breedings. Stillbirths of single male calves of heifers were more frequent for breedings with sexed semen (15.6%) than conventional semen (10.8%); a comparable difference was not observed for cows, for which stillbirth frequency of single male calves even decreased (2.6 vs. 3.6%). Overall stillbirth frequency was reduced by sexed semen use for cows but not for heifers.

258 CLASSIFICATION AND IDENTIFICATION OF THE CLONED HANWOO CALVES DERIVED FROM SOMATIC CELL NUCLEAR TRANSFER USING MS GENOTYPES AND mtDNA POLYMORPHISMS

The calves produced by somatic cell nuclear transfer (SCNT) had identical genetic background except for cytoplasmic transmission molecules, which originated from recipient oocytes. To identify the SCNT calves generated from 3 nucleus donors, genotypes for 16 microsatellite (MS) markers and mitochondrial DNA (mtDNA) polymorphisms were analyzed. Using MS genotypes, the parentage test results were not only classified as the single donor-derived calves but mtDNA sequence variations might also discriminated all SCNT calves within the donor-derived families. Comparing MS genotypes, AI-derived progenies were easily discriminated from each other. However, those genotypes could not supply the useful information for identifying the SCNT calves produced from each donor. Informative sequence variations were detected in several regions including D-loop, 12 S rDNA, and ND5 genes. About 19 nucleotide substitutions found within D-loop allowed individual identification for most SCNT-derived progeny except for 5 individuals. However, further investigation on 12 S rDNA and ND5 genes provided the useful polymorphic information for those 5 individuals. Although the experiment had been carried out to produce SCNT calves without previous investigation of mtDNA polymorphism, polymorphic mtDNA sequences provided interesting information that discriminated individuals, even those from the same donor cells. In addition, we could distinguish the 2nd generations produced by AI combinations using SCNT donors and SCNT progeny as the dams and/or the sires when combined molecular data obtained from MS genotypes and mtDNA polymorphisms were derived. These results suggested that mtDNA polymorphisms might supply the critical information for identification and traceability for SCNT-derived calves when combined with MS data. This work received grant support from the Agenda Program (No. 200901FHT010305191), Rural Development Administration, Republic of Korea.

Risk factors for perinatal mortality in dairy cattle: Cow and foetal factors, calving process

It was the aim of this study to identify risk factors of perinatal mortality (PM) on a large dairy farm in Germany. Four hundred and sixty-three cows were observed continuously around calving. Data such as the lactation number, body condition score, pelvic measurements, duration of second stage of labour (SSL), degree of abdominal press (AP), presentation/position/posture of the calf, calving classification, various measurements of the calves and every action of the barn staff were documented. Calves born dead and those that died within 24 h were classified as cases of PM. Logistic regression was performed to identify risk factors for the dependent variables PM, SSL and AP. 9.7% of all calves born ( n = 483) were classified as PM. In the logistic regression model, only SSL and presentation/position/posture of the foetus remained as significant effects for PM. The odds ratio for PM was 0.20, when SSL was ≤120 min, and 0.33, when the calves were born in anterior presentation, upper position and normal posture. With regard to SSL, primipara, insufficient AP, assisted calvings and as a trend, work shift changeover, these were risk factors for a prolonged SSL beyond 120 min. The risk for insufficient AP was lower when the calves were born spontaneously, in anterior presentation and as single calves. In conclusion, the duration of SSL and presentation/position/posture of the calf seemed to be key risk factors for PM. Interventions should be considered when SSL lasts longer than 2 h. Insufficient monitoring around parturition had a negative effect on the duration of SSL and thereby, indirectly on PM.

Sex ratio variation in harvested moose (Alces alces) calves: does it reflect population calf sex ratio or selective hunting?

During the last 30 years, the proportion of males in the calf harvest of moose (Alces alces) in Norway has decreased, indicating a decline in proportions of males recruited to the autumn populations. At the same time, the percentages of exclusive calf hunting permits and of calves shot have increased. The change in calf sex ratio may thus simply be the result of hunter preferences for slightly larger (6.2% higher body mass) male calves combined with fewer opportunities for selective hunting due to increasing hunting quotas of calves. We examined this hypothesis by analyzing the variation in sex, number of siblings, carcass mass, date, and location of kill of 16,330 moose calves harvested during 1970–2004. In the presence of hunting selection for larger calves, we predicted larger proportions of male calves to be harvested in populations with large sexual size dimorphism among calves. Similarly, we expected more males to be harvested from twin than single litters because hunters then can more easily compare twins and select the larger calf, which is more often a male. Increasing proportions of single female calves were also expected to occur in the daily harvest as the accumulated number of harvested calves increased and the proportion of calves left in the population decreased. We found no positive relationship between the proportion of male calves and the level of sexual size dimorphism, no clear difference in sex ratio between harvested single and twin calves, and no increase in the proportion of single female calves as the accumulated number of calves in the harvest increased. This suggests that the spatiotemporal variation in the harvest calf sex ratio in Norway most likely reflects differences in population calf sex ratios prior to the hunting season and not varying degrees of hunting selectivity.

Increased calf production in cattle selected for twin ovulations1,2

The effects of increasing fetal numbers and their distribution between the left and right uterine horns on calf survival, calf BW at birth and weaning, gestation length, dystocia, and calf sex ratio were evaluated for single (n = 1,587), twin (n = 2,440), and triplet calves (n = 147) born to primiparous and multiparous females in the Twinner population at the US Meat Animal Research Center between 1994 and 2004. Cattle were distributed equally between the spring and fall breeding seasons. Fetal number and distribution in utero were determined by real-time ultrasonography at 40 to 70 d postbreeding. For cows and heifers combined, number of calves per parturition increased from 1.34 in 1994 to 1.56 in 2004. Gestation length was 6.8 d shorter (P < 0.01) for twins compared with singles (277.5 +/- 0.2 vs. 284.3 +/- 0.2 d) and 12.7 d shorter for triplets (271.6 +/- 0.8 d). Survival and BW of individual calves at birth decreased (P < 0.01) but total calf BW per dam increased (P < 0.01) as fetal number increased from single to triplet births. Twins resulting from bilateral twin ovulations had increased (P < 0.01) survival and BW at birth, a longer (P < 0.01) gestation length, and less (P < 0.01) dystocia than twins resulting from unilateral twin ovulations. Calf survival and BW at birth were 97.2 +/- 0.3% and 48.0 +/- 0.1 kg for singles, 92.0 +/- 0.4% and 39.0 +/- 0.2 kg for bilateral twins, 83.2 +/- 0.4% and 36.7 +/- 0.2 kg for unilateral twins, 73.8 +/- 1.4% and 30.6 +/- 0.7 kg for bilateral triplets, and 51.9 +/- 3.2% and 31.7 +/- 1.6 kg for unilateral triplets. Birth weight of single calves increased by 0.51 kg/d for each additional day of gestation length vs. 0.38 kg/d for individual twins. Calf BW at birth increased (P < 0.01) with age of dam from 2 to 4 yr. Twin and triplet births had a greater (P < 0.01) incidence of dystocia than single births. The ratio of male:female calves (0.52:0.48) at birth was not affected by type of birth. Postnatal calf survival was similar for all 3 types of birth. Total progeny BW at weaning for single, twin, and triplet births was 217.7 +/- 2.5, 328.3 +/- 3.2, and 378.4 +/- 15.0 kg, respectively (P < 0.01). Although most bovine females have the uterine capacity to gestate twin calves, decreased survival and BW of unilateral twins and of all triplets indicate that their growth and development may have been compromised by uterine crowding.