An evaluation of visual assessment for fertility in Brahman cross cows using the Bonsma technique

A technique of visual assessment of cattle for reproductive efficiency, described by Professor Jan Bonsma of South Africa, was evaluated in two well-managed large herds of 1/2 to 3/4 Brahman cross heifers and cows located in the dry tropics of north Australia. Individual lifetime performance records were available for all animals. Experienced cattlemen carried out the assessments. Higher scores were previously claimed to indicate higher fertility. The technique had high repeatability (0.7) and was quickly learned by the assessors. Scores from visual assessment had no useful predictive value for either heifer or cow fertility or for growth rate up to 27 mo of age, although 2.5-yr-old heifers which were scored as subfertile matured into 4% smaller cows than heifers which had scored higher. Scores decreased as fatness increased (P < 0.05). Some biases in visual assessment occurred. Lactating cows scored higher than nonlactating cows (P < 0.05), independently of their reproductive record. Red and grey cows scored higher than brindle and black/brown cows (P < 0.05). Bonsma scores were not influenced by the percentage of Brahman in the genotype. Significant, but apparently random, age effects on scores also occurred. It was concluded that the visual assessment criteria described by Bonsma were of no practical value in assessing potential productivity of breeding animals in well-managed Brahman cross cattle in the dry tropics.     

Prevalence of Coxiella burnetii infection among humans and domestic animals of Rajasthan State, India

A total number of 1806 sera comprising 1049 humans and 757 animals from four ecologically different areas of Rajasthan State were tested to determine the prevalence of complement-fixing (CF) antibodies to Coxiella burnetii (C burnett). Of the 1049 human and 757 animal sera tested, antibodies to C. burnetii were detected in 195 sera (18.6 per cent) and 187 sera (24.7 per cent), respectively. Among humans, the prevalence of infection with C. burnetii was highest in the desert area of Barmer district and the hilly area of Bundi district, viz 64.5 per cent and 28.2 per cent, respectively. It was slightly lower in the semi-arid and the arid zones of the State, viz Sirohi (20 per cent) and Jalore (13.7 per cent), whereas the irrigated areas of Kota and Jaipur had the lowest prevalence, 9.9 and 8.4 per cent, respectively. Among animals, the highest prevalence was detected in sheep (39.6 per cent), followed by cattle (29.9 per cent) and goats (18.6 per cent).     

Evaluation of five resynchronization methods using different combinations of PGF2α, GnRH, estradiol and an intravaginal progesterone device for insemination in Holstein cows

This study was conducted to determine the use of repeated transvaginal ultrasound-guided cumulus oocyte complex (COC) aspiration on COC recovery rate, in vitro embryo production (IVP) and subsequent pregnancy rates in Holstein Friesian (HF) and Aberdeen Angus (AA) cows (Experiment 1), and in pregnant and non-pregnant Holstein Friesian cows (Experiment 2). Cycling, non-pregnant HF (n=17) and AA (n=32) cows with 40-70 days postpartum, between 3 and 5 years of age were used in the Experiment 1. All cows were submitted to repeated transvaginal ultrasound-guided COC aspiration twice a week for 5-7 weeks. Cumulus ooctye complexes (COC) were in vitro matured, fertilized and cultured for 8 days. An overall of 100 and 350 embryos from HF and AA cows respectively were cryopreserved using a conventional slow freezing (Experiment 1). A total of 81 and 285 frozen-thawed embryos from HF and AA cows respectively were transferred to recipient cows. Pregnancy diagnosis was performed at 60 and 150 days of gestation using transrectal ultrasonography. In Experiment 2, cycling non-pregnant (n=9) and pregnant (n=8) HF cows were submitted to repeated ultrasound-guided COC aspiration and COC were in vitro matured, fertilized and cultured as in Experiment 1, except that embryos were cryopreserved but not thawed and transferred as described for Experiment 1. The results of this study indicate that COC recovery rate and blastocyts production are affected by the breed of the donor cow. The quality of blastocyts produced from both breed did not differ in terms of pregnancy and calving rates (Experiment 1). The physiologic state of pregnancy did not affect COC recovery rate and blastocysts production per donor/session (Experiment 2). The use of ultrasound-guided COC aspiration and IVP could be a powerful technique to improve the genetic of beef and dairy cattle managed under pasture-based conditions management in the southern Chile.     

Relationships of weight and height with age in hybrid Holstein-Friesian/Guzera females

Serial data on live weights, height at withers and the weight/height ratio of 263 cows (3 to 9 years old) and 196 heifers (2 to 5 years old) were studied. The animals were of six red and white Holstein-Friesian (HF)/Guzera crosses (1/4, 1/2, 5/8, 3/4, 7/8 and > or = 31/32 HF-expected gene fraction). Separate analyses were performed for cows and heifers using the Proc Mixed of the SAS package. Models included the fixed effects of farm, season, reproductive and lactation status, two-factor interactions, quadratic regressions on age and age x crossbred group interaction, as continuous co-variables and regressions on the HF gene fraction and on breed heterozygosity, plus the animal random effect. Only heifer growth in height and weight/height was linear with age. In all three traits in both categories the individual additive-dominance model explained the variation between crossbred groups. The breed additive difference was not significant (P > 0.05) for cow and heifer live weight and for heifer weight/age ratio. Heterosis was significant for all traits except height of cows. Linear and quadratic regression coefficients for cows, were, respectively, for live weight, 35.20 +/- 5.23 kg/year and -1.54 +/- 0.43 kg/year2, for withers height, 2.49 +/- 0.29 cm/year and -0.15 +/- 0.02 cm/year2 and for weight/height, 0.22 +/- 0.04 kg/cm/year and -0.01 +/- 0.003 kg/cm/year2. Corresponding values for heifers were, for live weight, 153.46 +/- 37.06 kg/year and -15.69 +/- 4.91 kg/year2, while only linear coefficients applied to withers height (1.63 +/- 0.43 cm/year) and weight/height (0.16 +/- 0.03 kg/cm/year).     

Influence of management factors on pregnancy attrition in dairy cattle

The present study was conducted to determine the influence of management factors on pregnancy attrition in dairy cattle. Data from 3162 diagnosed pregnancies in parous cows and 1050 in heifers at 9 commercial dairy herds in northeastern Spain were used. Pregnancy diagnosis by palpation per rectum was performed from 30 to 70 d post insemination. Pregnancy attrition was registered when pregnancy diagnosis resulted negative in a second palpation carried out between 120 and 150 d following insemination. Overall proportion of pregnancy losses was 7.9% (9.6% in parous cows and 2.8% in heifers). Data analysis was performed by multiple logistic regression methods. For all animals, effect of time of pregnancy diagnosis was shown (Odds ratio = 0.97 for 1 d increase; P = 0.0042). Conceptus loss in heifers was lower than in parous cows (Odds ratio = 0.28; P = 0.0001), and a higher proportion of pregnancy attritions was detected in animals inseminated in spring, summer and winter, compared to those inseminated in autumn (P < 0.04). Herd effect on pregnancy attrition was also significant. Similar results were observed in the subanalysis for parous cows and, furthermore, no effect of lactation number and of interval from previous calving to pregnancy was shown in this group. In heifers, no effect of time of pregnancy diagnosis and of insemination season on pregnancy attrition was shown, and only a herd effect was observed. Our data suggest that the influence of parity status (heifer vs cow) could affect the proportion of pregnancy attrition rather than early diagnosis, and, in pregnant cows, adaptation to seasonal changes associated with temperature decreases seem more efficient.     

Bovine viral diarrhea virus: its effects on estradiol, progesterone and prostaglandin secretion in the cow

Bovine viral diarrhea virus (BVDV) is a major cattle pathogen responsible for a spectrum of symptoms, including reproductive failure. This study was designed to establish the effects of BVDV infection on estradiol, progesterone and PGF2alpha secretion in the cow. Seven BVDV-free cows were challenged with non-cytopathogenic BVDV (strain Pe 515: 5x10(6) tissue culture infected dose50) so that peak viremia occurred during the initial phase of luteal development in a synchronized estrous cycle. Ovulation was also synchronized in 7 sham-infected animals. Within 2 wk of inoculation, viremia, leukopenia and serum neutralizing antibodies were recorded in all of the BVDV-infected cows but not the sham-infected animals. Between Day 4 and Day 9 post estrus the BVDV-infected cows had significantly (P<0.01) lower plasma estradiol levels than the sham-infected animals. However, the BVDV infection did not alter rectal temperatures, plasma progesterone concentrations or PGF2alpha secretion 17, 18 and 19 d post estrus. These data highlight a potential causal link between BVDV viremia, endocrine dysfunction and poor fertility in the cow.     

The developmental competence of bovine nuclear transfer embryos derived from cow versus heifer cytoplasts

Due to its economic importance, the production of cattle by nuclear transfer has been a primary research focus for many researchers during the past few years. While many groups have successfully produced cattle by nuclear transfer, and progress in this area continues, nuclear transfer remains a very inefficient technology. This study evaluates the effect of the oocyte source (cow and heifer) on the developmental competence of nuclear transfer embryos. In order for nuclear transfer to be successful, a differentiated donor cell must be reprogrammed and restored to a totipotent state. This reprogramming is probably accomplished by factors within the oocyte cytoplasm. This study indicates that oocytes derived from cows have a greater capacity to reprogram donor cell DNA following nuclear transfer as compared to heifer oocytes based on in vitro development to the 2-cell stage and to the compacted morula/blastocyst stages. Nuclear transfer embryos derived from cow oocytes resulted in significantly higher rates of pregnancy establishment than embryos derived from heifer oocytes and resulted in higher pregnancy retention at 90 and 180 days and a greater number of term deliveries. Following delivery more calves derived from cow oocytes tended to be healthy and normal than those derived from heifer oocytes. The differences in developmental efficiency between nuclear transfer embryos derived from cow and heifer cytoplasts demonstrate that subtle differences in oocyte biology can have significant effects on subsequent development of nuclear transfer embryos.     

Genetic variation in milk urea nitrogen concentration of dairy cattle and its implications for reducing urinary nitrogen excretion

Nitrogen (N) leached into groundwater from urine patches of cattle grazing in situ is an environmental problem in pasture-based dairy industries. One potential mitigation is to breed cattle for lower urinary nitrogen (UN) excretion. Urinary nitrogen is difficult to measure, while milk urea nitrogen concentration (MUN) is relatively easy to measure. For animals fed diets of differing N content in confinement, MUN is moderately heritable and is positively related to UN. However, there is little information on the heritability of MUN, and its relationship with other traits such as milk yield and composition, for animals grazing fresh pasture. Milk urea nitrogen concentration data together with milk yield, fat, protein and lactose composition and somatic cell count was collected from 133 624 Holstein-Friesian (HF), Jersey (J) and HF×J (XBd) cows fed predominantly pasture over three full lactations and one part lactation. Mean MUN was 14.0; and 14.4, 13.2 and 13.9 mg/dl for HF, J and XBd cows, respectively. Estimates of heritability of MUN were 0.22 using a repeatability model that fitted year-of-lactation by month-of-lactation by cow-age with days-in-milk within month-of-lactation and cow-age, and 0.28 using a test-day model analysis with Gibbs sampling methods. Sire breeding values (BVs) ranged from −2.8 to +3.2 indicating that MUN could be changed by selection. The genetic correlation between MUN and percent true protein in milk was −0.22; −0.29 for J cows and −0.16 for HF cows. Should the relationship between MUN and UN observed in dietary manipulation studies hold similarly when MUN is manipulated by genetic selection, UN excretion could be reduced by 6.6 kg/cow per year in one generation of selection using sires with low MUN BVs. Although J cows had lower MUN than HF, total herd UN excretion may be similar for the same fixed feed supply because more J cows are required to utilise the available feed. The close relationship between blood plasma urea N concentration and MUN may enable early selection of bulls to breed progeny that excrete less UN.     

Comparisons between nulliparous heifers and cows as oocyte donors for embryo production in vitro

The aims of the present study were to compare (1) Holstein-Friesian heifers versus early postpartum lactating cows, and (2) different age categories of crossbred beef heifers versus cows, in terms of oocyte yield, morphological quality and developmental competence. Four experiments were designed to test the associated hypotheses. In Experiment 1, ovum pick up was carried out twice weekly for a period of 5 weeks on Holstein-Friesian heifers (n = 8) and early postpartum cows (n = 8). Oocytes were submitted to in vitro maturation (IVM), fertilization and culture. Significantly more follicles were punctured on the ovaries of heifers than cows (10.4 versus 7.8, P < 0.001). This was reflected in a significantly higher number of total oocytes (4.7 versus 2.8, P < 0.001) and grade 1-2 oocytes recovered/animal from heifers than from cows (3.0 versus 1.8, P < 0.05). There was no significant difference in the percentage of oocytes cleaving after fertilization, or in the percentage reaching the blastocyst stage between heifers and cows. In Experiment 2, oocytes were obtained by manual aspiration from the ovaries of slaughtered crossbred beef heifers (under 30 months, n = 1241) and cows (over 4 years old, n = 1125), and processed in vitro as above. No significant difference was observed between the two groups in terms of the number of aspirated follicles or oocytes recovered. A significantly higher proportion (P < 0.01) of cow oocytes than heifer oocytes reached the blastocyst stage (Day 8: 46.5% versus 33.4%). In Experiment 3, ovaries were separated according to age of heifer into three groups: (1) 12-18 months, (2) 19-24 months and (3) 25-30 months, and compared with cow oocytes. There was no significant difference in the blastocyst yield between the different age groups of heifers. Irrespective of heifer age, the blastocyst yield on Day 8 was significantly lower than that from cow oocytes (35.0, 35.2, 36.5 and 48.3%, respectively, P < 0.05). In Experiment 4, a significantly higher proportion (P < 0.001) of presumptive zygotes derived from abattoir-derived cow oocytes reached the blastocyst stage following culture in vivo in the ewe oviduct than those derived from heifer oocytes (Day 8: 53.1% versus 25.2% for cow and heifer oocytes, respectively). In conclusion, the origin of the oocyte has a significant impact on its subsequent developmental potential. These results would suggest that in an in vitro production system, cow oocytes should be preferentially used over those from heifers in order to maximize blastocyst development.     

Epidemiological survey of rhinosporidiosis in Kanyakumari district of Tamil Nadu

One hundred and twelve nasal polyps received along with full history from three different hospitals of Kanyakumari district of Tamil Nadu during the period 1983–1987 were found positive for rhinosporidiosis on histopathological examination. Among the four taluks (countries) the majority of the cases (41.1 per cent) came from Agastheeswaram, followed by Kalkulam (28.6 per cent), Thovalai (17.0 per cent) and Vilavancode (13.3 per cent). The 11–20 years age group found to be highly susceptible (60 per cent). There was no sex prepondence in contracting the disease as the cases were evenly distributed between both sexes. These findings exhibited the endemic nature of the disease in Kanyakumari district.Unreported cases to an extent of 9 to 40 per cent were encountered during the ENT disease diagnostic camps conducted in nine high incidence villages. Further 8 more cases were detected in addition to cases attended in the hospitals and ENT camps when a complete enumeration of cases was undertaken in Pallam village. Thus the actual number of cases found in the district need a stratified random sampling.     

Restricting dairy cow access time to pasture in early lactation: the effects on milk production, grazing behaviour and dry matter intake

One of the main aims of pasture-based systems of dairy production is to increase the proportion of grazed grass in the diet. This is most easily achieved by increasing the number of grazing days. However, periods of inclement weather conditions can reduce the number of days at pasture. The two objectives of this experiment were: (i) to investigate the effect of restricting pasture access time on animal production, grazing behaviour and dry matter intake (DMI) of spring calving dairy cows in early lactation; and (ii) to establish whether silage supplementation is required when cows return indoors after short grazing periods. In all, 52 Holstein-Friesian spring calving dairy cows were assigned to a four-treatment study from 25 February to 26 March 2008. The four treatments were: full-time access to pasture (22H; control); 4.5-h- pasture access after both milkings (2 × 4.5H); 3-h pasture access after both milkings (2 × 3H); 3-h pasture access after both milkings with silage supplementation by night (2 × 3SH). All treatments were offered 14.4 kg DM/cow per day herbage from swards, with a mean pre-grazing yield of 1739 kg DM/ha above 4 cm, - and were supplemented with 3 kg DM/cow per day of concentrate. The 2 × 3SH treatment was offered an additional 4 kg DM/cow of grass silage by night. Restricting pasture access time (2 × 3H, 2 × 3SH and 2 × 4.5H) had no effect on milk (28.3 kg/cow per day) and solids-corrected milk (27.2 kg/cow per day) yield when compared with the treatment grazing full time. Supplementing animals with grass silage did not increase milk production when compared with all other treatments. Milk protein concentration tended to be lower (P = 0.08; 32.2 g/kg) for the 2 × 3SH animals when compared with the 22H animals (33.7 g/kg). The grass DMI of the 2 × 3SH treatment was significantly lower (-2.3 kg DM/cow per day) than all other treatments (11.9 kg DM/cow per day), yet the total DMI of these animals was highest (16.6 kg DM/cow per day). The 22H cows grazed for 481 min/cow per day, which is significantly longer than all other treatments. The 2 × 3H animals grazed for 98% of the time, whereas the 2 × 3SH grazed for 79% of their time at pasture. Restricting pasture access time did not affect end body weight or body condition score. The results of this study indicate that restricting pasture access time of dairy cows in early lactation does not affect milk production performance. Furthermore, supplementing cows with grass silage does not increase milk production but reduces grazing efficiency.     

Endocrine Measurements and Calving Performance of Swedish Red and White and Swedish Holstein Dairy Cattle with Special Respect to Stillbirth

During 3 consecutive calving seasons, calving performance, placental characteristics and endocrine profiles of total 98 pregnancies of late pregnant Swedish Red and White (SRB) and Swedish Holstein (SLB) dairy heifers and cows, were investigated. Ninety-four singleton pregnancies and 4 sets of twins were recorded. In animals with singleton pregnancy, 8 stillbirths, 7 weak calves, 3 premature parturitions and 1 abortion were registered. In the SLB heifers, 19% of stillbirth (5/26) were observed, while 5% (2/42) were noted for the SRB heifers. One stillborn calf derived from the SRB cows and none was found from the SLB cows. In the heifers and cows delivering a normal living calf with unassisted parturition, the placentome thickness monitored by ultrasonography was constant towards the end of pregnancy. The numbers of foetal cotyledons varied individually between animals but in total, fewer cotyledons were found in the foetal membranes of the SRB animals than in the SLB animals (69 ± 19) vs. (88 ± 29) (p < 0.05). No morphological and numerical differences of the placentome thickness in animals delivering a stillborn or weak calf, compared to animals delivering a normal living calf, could be observed. In animals with unassisted parturition and without birth complications, the levels of progesterone (P4), PGF_2α metabolite (PG-metabolite), cortisol, oestrone sulphate (E1SO4) and pregnancy associated glycoproteins (PAGs) were not different by breeds and parities. In animals carrying stillbirth, higher levels of E1SO4 were found in 3 SRB animals and 1 SLB heifer, whereas lower levels of E1SO4 were recorded in 3 SLB heifers during the last week of pregnancy, compared to the profiles found in animals with unassisted parturition. Additionally, the levels of PAGs remained low and constant in 1 SRB cow (delivering a stillborn calf), 1 SRB heifer (giving birth prematurely), 4 animals (carrying twins) and 1 aborting SRB cow. Our results show a very high rate of stillbirth in especially SLB heifers and deviating profiles of E1SO4 and PAGs in animals with impaired parturition were recorded.     

Bluetongue virus serotype 8 (BTV-8) infection reduces fertility of Dutch dairy cattle and is vertically transmitted to offspring

In 2007, BTV-8 re-emerged for the second year in the Netherlands and caused morbidity and increased mortality in cattle herds. In addition, cattle farmers reported reduced fertility in their cows. For this study, fifteen herds that were not vaccinated were selected. These were matched to 10 vaccinated herds by geographic region. At the start of the study, in July 2008, all cattle in the non-vaccinated herds >1 year old were sampled. All seronegative cows entered the study program and blood samples from these cows were tested for antibodies against BTV-8 in an ELISA. Cows were sampled at intervals of three weeks and sampling was stopped once a cow tested seropositive. Sampling ceased in all remaining cows in December 2008.Newborn calves originating from infected dams or from vaccinated dams were tested by PCR for BTV-8. Fertility data were obtained from the Royal Dutch Cattle Syndicate (CRV). Multi-level generalized latent and linear models were used for analyses.In 2008, 185 (17.2%) out of 1,074 initially seronegative non-vaccinated cattle seroconverted and were assumed to be infected with BTV-8. Infected cows were 5 (95% CI: 1.9-14.3) times more likely to return for insemination within 56 days after first insemination. In addition, these cows needed 1.7 (95% CI: 1.4-2.0) times more inseminations for an assumed pregnancy, and needed 2.5 (95% CI: 2.4-2.6) times more days between first and last insemination compared to the period prior to seroconversion and compared to cows not infected by BTV-8 in 2008. No association between BTV-8 infection and the chance to abort between 100 and 260 days after last insemination was found.In total, 48 calves originating from infected cows were tested by PCR for the presence of BTV-8. Ten (20.8%) out of these 48 calves were born PCR-positive. None of 256 calves from vaccinated dams tested PCR-positive. Further, cows infected during the second half of gestation had a 15.5 times (95% CI: 1.3-190.4) higher chance of a PCR-positive newborn calf compared to cows infected in the first half of gestation. This study showed that BTV-8 has a negative effect on fertility of dairy cattle.     

The number of farm mates influences social and maintenance behaviours of Japanese Black cows in a communal pasture

The objective of the present study was to investigate optimal group size in cattle in communal pastures where cattle from various farms are turned out: (1) to ascertain if cows derived from each farm form an affiliative group and (2) to investigate the effect of the number of farm mates on social and maintenance behaviours when farm mates form an affiliative group. Farm mates were defined as cows from the same farm. A total of 27 cows having zero, one, two to four, or sixteen farm mates were selected as focal animals in two communal pastures. Each focal animal was followed by an individual observer for 8 h from sunrise. The nearest neighbour and the distance to the nearest neighbour were recorded at 10-min intervals, and maintenance behaviours at 1-min intervals; social behaviours and participants were recorded continuously. Most focal animals frequently choose cows from the same farm as their nearest neighbours allogroomed with these farm mates significantly more (P<0.001). Two focal animals did not form affiliative groups with farm mates. The mean distance to the nearest neighbours, whether farm mates or non-farm mates from focal animals having one and two to four farm mates was shorter than cows turned out with no farm mate (1.4 vs. 1.9 times as long as a cow's body length, P<0.05). Cows having two to four farm mates performed (7.8 s/h/cow, P=0.06) and received allogrooming more (9.8 s/h/cow) and escaped less during agonistic encounters (0.1 frequencies/h/cow, P<0.01) than ones having other numbers of farm mates. The mean duration of grazing behaviour per bout tended to increase with the number of farm mates (5.2 to 10.3 min, P<0.05). The mean duration of recumbency behaviour of cows having two to four farm mates (44.0 min/bout) was longer than the ones having other numbers of farm mates. Social and maintenance behaviours of cows having 16 farm mates were like those having zero or one farm mates, which suggested that the social bond among them was weak. It is concluded that a group of cows having two to four farm mates, that is, a group size of three to five cows, may be optimal for a stable life in a communal pasture.     

Mathematical simulation of the selection process in a dairy herd

The effect of intensity of selection for parentage and individual performance of cows, according to age structure, genetic gain and average production was studied in a dairy unit per 2000 stable places. The maximum genetic gain was achieved as a result of combined selection of cow dams when 66 per cent of heifers were selected for parentage and 20 per cent of first-calvers were culled for their performance (26.5 replacements). With increase in the selection intensity, the average milk yield increased by 3-6 per cent but the genetic efficiency of cow dams selection decreased by 10-37 per cent.     

Case Study: Composite Material Yoke Versus Wooden Yoke for Bullocks’ Comfort

This article addresses the designing of a yoke used to get work output (plowing) from bullocks. The yoke profile was designed in compliance with the profile of the bullock’s body for maximum contact area. Unlike the crude, wooden yoke used in rural India, where modern tilling equipment like a tractor is not affordable, the present yoke was smooth, free from sharp edges, and light in weight. A field study was carried out with bullocks using composite and wooden yokes. The fatigue of bullocks was measured in terms of respiration rate and heart rate. Data revealed that bullocks had less fatigue with composite material yoke than with the wooden yoke. The experimental investigation also showed that at a 30º angle of pull, bullocks feel maximum comfort when they are used for plowing purposes.     

Viability of bovine demi- and quarter-embryos after transfer

The viability of bovine demi- and quarter-embryos was investigated. Early compacting morulae were nonsurgically flushed from superovulated donor cows and were bisected by two microneedles. One of the halves was then split further into two quarters. Each demi- and quarter-embryo was placed in an evacuated zona pellucida. One demi- or two quarter-embryos were transferred non-surgically into cow or heifer recipients. Viability was measured by ultrasound scanning of the fetuses on Days 35, 48 and 60 of pregnancy. The pregnancy rates at Day 60 were 46.2% (6 13 ) for heifers and 33.3% (4 12 ) for cows after the transfer of a single demi-embryo. The transfer of two quarter-embryos resulted in a pregnancy rate of 61.5% (8 13 ) for heifers and 8.3% (1 12 ) for cows. Seven (53.8%) and four (33.3%) live fetuses were found on Day 60 following the transfer of demi-embryos into heifers and cows, respectively. The transfer of quarter-embryos resulted in 10 fetuses (38.5%) in the heifer recipients and only one fetus (4.2%) in the cow recipients. The results of this study suggest that heifers are more suitable than cows as recipients for quarter-embryos.     

Correction: Periconceptional Heat Stress of Holstein Dams Is Associated with Differences in Daughter Milk Production and Composition during Multiple Lactations

The fertility of lactating Holstein cows is severely reduced during periods of heat stress. Despite this reduction in fertility, however, some inseminations conducted during heat stress result in successful pregnancies from which heifer calves are born. Many of these heifer calves are retained and raised to enter the milking herd as replacement animals. Heat stress experienced by these females around the time they were conceived may confer long-lasting effects that alter subsequent milk production capacity. The objective of this study was to examine the relationship between periconceptional heat stress and subsequent milk production of primiparous cows. National Dairy Herd Improvement Association data was obtained from Dairy Records Management Systems. Records included Holstein cows that had completed at least one lactation in one of three states with large populations of dairy cattle and which are known for having hot, humid summers: Georgia, Florida or Texas. Dates of conception were calculated by subtracting 276 d from the recorded birth date of each individual cow. Records for cows conceived within the months of June, July, and August were retained as heat stress-conceived (HSC) cows (n = 94,440); cows conceived within the months of December, January, and February were retained as thermoneutral-conceived (TNC) contemporaries (n = 141,365). In order to account for the effects of environmental conditions on total milk production for a given lactation, cows were blocked by season of calving (winter, spring, summer or fall). Adjusted 305-day mature-equivalent milk production was evaluated with a mixed model ANOVA using SAS, in which random effects were used to account for variability between herds. Of the cows that calved in the summer, fall and winter, TNC cows had higher milk yield than the HSC cows in all states. Interestingly, the cows that calved in the spring presented a unique relationship, with HSC cows producing more milk. Overall however, heat stress at the time of conception is associated with lower milk production during the first lactation. While this association does not prove cause and effect, it does provide justification for additional investigation into whether heat stress around the time of conception results in long-term, detrimental consequences for the conceptus.     

Factors Prior to Dry Period Associated with High and Low Levels of Cow Milk Somatic Cell Counts in Next Lactation

Data from a randomized controlled field study of selective dry cow therapy were used in which 686 cows had been allocated to 2 control groups (sampling only or placebo) or 2 therapy groups. Possible factors from previous lactation were assessed in determining their association with the probability of ‘failure’, designated as a cow milk somatic cell count (CMSCC) of greater than 399000 per ml in geometric mean of several measurements during subsequent lactation. Success cows were those with a CMSCC of less than 200000 per ml. For our analyses, this targeted 187 success cows and 186 failure cows. Therapy was given as a total dose of 400000 IU penicillin and 100 mg neomycin per infected quarter as dry cow preparation once, or as a lactation formula with a total dose of 1.2 million IU penicillin and 1200 mg dihydrostreptomycin per infected quarter during a 1-week period. Significant factors in the predictive model for success included therapy, low level of CMSCC (geometric mean of the 3 last tests) in previous lactation, low level of CMSCC (weighted by daily milk yield mean) in the herd, young cows, and not having had a case of treatment for chronic clinical mastitis. Additional information on the probability of failure in treated and untreated cows can be predicted by number of quarters infected with Staphylococcus aureus approximately 1.5 months before drying off. The models derived are considered for use as tools in selective treatment and culling decisions.     

Transplacental transmission and abortion in cows administered Neospora caninum oocysts

Neospora caninum infection is a common cause of bovine abortion. One method by which cattle can acquire infection is through ingestion of oocysts; however, this has not yet been proved to cause transplacental infection or abortion. In this study, 19 cows, pregnant between 70 and 176 days, were administered 1500 to 115,000 oocysts through an esophageal tube. Seventeen of the cows became seropositive, indicating acquisition of infection, whereas 8 negative control cows remained seronegative (P < 0.001). Offspring were examined using serology, histology, immunohistochemistry, parasite isolation, and polymerase chain reaction (PCR). Six offspring were infected and 1 of them was aborted. The aborted fetus had typical lesions and positive immunohistochemistry and PCR for N. caninum. All 6 cows with infected offspring had continuously rising antibody titers, whereas 10 of 11 infected cows with uninfected offspring had falling titers after an early apex. The risk of transplacental transmission was increased by later exposure times during gestation and by the dose of oocysts (P < 0.01 for the 2 combined variables). The lowest dose of oocysts, when administered after the 160th day of gestation, caused transplacental infection in 1 of 2 animals. This study demonstrates that infection with N. caninum oocysts can cause transplacental transmission and abortion in cattle.