Genotype by environment interaction for livability of dairy calves from first parity cows

Death of calves around parturition is a matter of concern for dairy farmers. Relatively high stillbirth rates and unfavourable trends have been reported for Holstein heifers in the Netherlands and several other countries. In our study, we investigated herd differences, genetic parameters and genotype by environment interaction for heifer calf livability. A large dataset with data from calvings between 1993 and 2012 of Dutch dairy farms was used. There were considerable differences between herds in livability of calves from heifers, with averages ranging from 74% to 95%. Both herds with relatively high and low averages showed the same negative trend between 1993 and 2012, with largest declines in herds with the lowest averages. We found that heritability and genetic variation of first parity livability were substantially larger in herd environments where the likelihood of stillbirth was high v. environments where stillbirth was at a low level. The genetic correlations between herd environment levels were all very close to unity, indicating that ranking of sires was similar for all environments. However, for herds with a relatively high stillbirth incidence selecting sires with favourable breeding values is expected to be twice as profitable as in herds with a relatively low stillbirth incidence.     

A survey on management and housing of peri-parturient dairy cows and their calves

Housing and management around the time of calving impact dairy cow behaviour, health and welfare, but little is known about current practice. The aim was to provide an overview of current calving practice and the study describes the main calving housing and management based on replies to an online questionnaire by 42 dairy cattle experts in 28 countries, or regions, in Europe, Canada and USA. The survey suggests that in the majority of countries and regions included in this study, dairy cows typically calve in indoor calving facilities; either individual pens, group pens or a system where the cow is moved from a group pen into an adjacent individual pen before calving. Regarding individual calving pens, the survey suggests that in the majority of countries and regions included in this study, most pens have open sides and offer cows no opportunity to isolate, although research shows that a secluded corner of an individual pen creates a preferred calving site. Further, the survey suggests that when cows calve in individual calving pens or tie-stalls, they are often moved there with signs of imminent calving, although research shows that this practice increases the duration of calving and it is recommended to move cows before their expected calving time. Regarding group pens, none of the 42 respondents replied that group pens typically offer cows the opportunity to isolate at calving. Recent research suggests that when cows calve in a secluded area of a group calving pen, this reduces the risk of failure of passive transfer of immunity. Regarding calving facilities where group pens are combined with adjacent individual pens, this was reported to be the most typical in 10 of the 24 countries and regions with indoor calving sections covered by the survey. The same concerns regarding when the cow is moved from the group pen to an individual pen apply, as outlined above. Irrespective of pen type, the most frequently reported surface was deep bedded straw and the most frequent type of separation between pens was open sides. Cow-calf separation within 12 hours of birth, and thereafter individual housing of calves combined with milk feeding via a teat bucket or bar was indicated the most frequent management. The survey presents experts’ evaluations of current practice of housing and management of peri-parturient dairy cows and their calves, and suggests that there is a discrepancy between current calving management and housing and recommendations based on recent research.     

Behavioural response to humans and the productivity of commercial dairy cows

This study examined the relationships between the attitude and the behaviour of the stockperson towards cows and the behavioural response to humans and the milk production of cows at 31 commercial dairy farms over one lactation. The attitude of the stockperson was measured on the basis of the stockperson's opinion of the cow's behaviour and how the stockperson evaluated his own behaviour. The behaviour of the stockperson was measured by recording the nature and frequency of the tactile interactions and some visual and auditory interactions directed towards the cows. The behavioural response of cows to humans was assessed by observing their approach behaviour to an unfamiliar experimenter in a standard test and production records were collected for the entire lactation at each farm. Correlation and regression analyses using farm averages were used to examine relationships between human and cow variables. Several cow behaviour variables, indicative of fear of humans, were moderately (P<0.05) to highly (P<0.01) correlated with milk yield and composition and regression analysis indicated that fear of humans accounted for 19% of the variation in milk yield between farms. The results suggest that at farms where milk yield was low, cows showed less approach to the experimenter in the standard fear test than at farms where milk yield was higher. A composite attitude score, based on the responses of stockpeople to questions about patting and talking to cows, ease of movement of cows and cows recognising unfamiliar stockpeople, was moderately (P<0.05) to highly (P<0.01) correlated with the behaviour of the stockperson. While a number of stockperson behaviour variables were correlated (P<0.05) with milk yield, the former variables were generally poorly correlated with cow behaviour. Therefore these preliminary findings provide evidence that, as seen in the pig industry, sequential relationships may exist between the attitude and behaviour of the stockperson and the behaviour and productivity of commercial dairy cows. Research is required to further examine these relationships because of the possible implications on cow productivity and welfare.     

Pastoral dairy marketing and household wealth interactions and their implications for calves and humans in Ethiopia

Surveys of pastoral households in a semi-nomadic Borana community during 1987–1988 were used to test the hypothesis that poorer families living closest to a market town would be most affected by the enhanced opportunity to sell dairy products, which would intensify competition between people and calves for milk and have negative implications for calf management. These poorer families indeed reported the highest rates of milk offtake per cow, and the milk increment was probably sold to purchase more grain for human consumption at the expense of milk intake for the calf. Consequently, this strategy may increase the susceptibility of malnourished calves to disease, especially those from lower-producing dams. Benefits of improved human energy intake from grain and retention of livestock capital must be weighed against risks of calf death and possible malnutrition of people from milk restriction when assessing dairy marketing trade-offs that are most acute for the poor. Opportunity to sell dairy products at favorable terms of trade helps the poorest people survive, and their risks could be mitigated by policies that facilitate grain marketing in the rangelands and interventions that improve calf feeding management, diversify human diets, and create alternative opportunities for women to generate income. The households postulated to be most at risk were identified from a complex, but logical, interaction among factors of distance to market, household wealth, and the quality of milking cows held. This indicates that targeting such needy groups for development assistance may require a more detailed and interdisciplinary analysis of production systems than is commonly practiced.     

Supplementation of antioxidant micronutrients reduces stress and improves immune function/response in periparturient dairy cows and their calves

BackgroundPeriparturient period induces stress in cows which fluctuates hormonal and metabolic function and causes immune suppression. Apart from impairing the health, production, and reproduction of cows, it also influences the well-being of newborn calves by decreasing the colostrum quality. Micronutrients are known for optimal health and production and their effects on parturition stress, immune response in both cow and its calf need to be explored.AimThe aim of this study was to see the effect of oral supplementation of micronutrients during the prepartum period on the health status of crossbred dairy cows and subsequently on their newborn calves.MethodsA total of 42 healthy multiparous cows were selected and randomly divided into five groups with seven cows in each group, i.e. control (Basal Diet, BD), VA group (BD + vitamin A, 10⁵ IU), Zn group (BD + zinc sulphate, 60 ppm), VE group (BD + vitamin E, 2500 IU), and combined supplementation (CS) group (BD + combination of VA, Zn, and VE). The supplements were offered in compounded concentrate DM (100 g) to individual cows once daily before the morning feeding and the remaining portion was incorporated in the TMR. Feeding was started one month before the expected days of calving till calving. Blood samples were collected from cows at days -15, -7, -3, 0, +3, +7, and +15 relative to the day of calving. Blood samples from newborn calves and milk samples of cows were collected at days 0, +3, +7, and +15. Milk somatic cell counts (SCC) were estimated using a cell counter. Cortisol was estimated by ELISA kit in blood and milk plasma of cows and in the blood plasma of their calves. Total immunoglobulins (Ig) were estimated in milk of cows and serum of calves using zinc sulphate turbidity method. Blood neutrophils from cows and calves were studied for phagocytic activity (PA) using nitro blue tetrazolium (NBT) assay.Data were analysed by repeated-measures two-way ANOVA using the mixed procedure of SAS, and the pairwise comparison was performed using a multiple comparison test (Tukey).ResultsCombined supplementation of micronutrients decreased (P < 0.05) maternal blood plasma (control vs. CS group, 5.98 ± 0.20 vs. 3.86 ± 0.23 ng/mL) and milk plasma (3.96 ± 0.13 vs. 2.71 ± 0.10 ng/mL) cortisol, milk SCC (3.05 ± 0.11 vs. 2.12 ± 0.10 × 10⁵ cells/mL) and increased (P < 0.05) total milk Ig concentration (18.80 ± 0.11 vs. 23.04 ± 0.57 mg/mL) and the PA of blood neutrophils (0.84 ± 0.03 vs. 1.07 ± 0.03). Similarly, lower blood cortisol concentration (9.69 ± 0.35 vs. 6.02 ± 0.18 ng/mL) and higher (P < 0.05) total Ig (23.26 ± 0.11 vs. 30.34 ± 0.70 mg/mL) and PA of blood neutrophils (0.37 ± 0.02 vs. 0.52 ± 0.02) were observed in the calves born to CS group of cows as compared to the control. Highest (P < 0.05) positive effects (lower stress levels and higher immune response) of treatment were noticed in CS group followed by VE group and then Zn group. However, VA group didn’t differ from the control group.ConclusionOur results indicate that micronutrient interventions during the prepartum period can improve the health status of dairy calves and subsequently the well-being of their calves.     

Animal performance and stress at weaning when dairy cows suckle their calves for short versus long daily durations

Calves in most dairy farms are separated from their dams either immediately or within a few hours after birth, prompting increasing concern of the society for reasons of animal welfare. The aim of this study was to identify systems to maintain cow-calf contact (CCC) that balance the benefits for calf growth and health against the negative impacts on sellable milk and stress at weaning. We tested reuniting cows and calves for 20 min before (Before-group) or 2.5 h after (After-group) morning milking (in Trial 1) or for a 9 h period between the morning and evening milkings (Half-day-group, in Trial 2). In Control-groups, calves were separated from their dam at birth and fed with artificial nipple with tank milk provided daily at 13% (Trial 1) and 14% (Trial 2) of their BW. In both trials, each practice was applied on a group of 14 dam–calf pairs (7 Holstein [Ho] and 7 Montbéliarde [Mo]). All calves were weaned at a BW of at least 100 kg. In Trial 1, the After-group was prematurely stopped when the calves were eight weeks of age as calf growth became limited (340 g/d) due to low milk intakes (2.97 kg/d). During the first eight weeks of lactation, milk yield at the parlour was 29%, 51% and 42% lower in After-, Before- and Half-day-cows respectively compared to Controls. From week 14 to 16 when all calves were separated from their dam, Before-cows still produced 25% less milk than Control-cows while Half-day-cows reached the milk yield of Control-cows within a week. There were no significant differences in milk somatic cell count and in frequency of health disorders (cows and calves) between suckling and Control-groups. Compared to Control-calves, calf growth until weaning was higher in the suckling calves in Trial 1 (861 vs 699 g/d) and similar in Trial 2 (943 vs 929 g/d). At weaning, Before- and Half-day-calves started to vocalise earlier and continued to vocalise longer than Controls. In conclusion, the best compromise between cow milk yield and calf growth is a long period of CCC (9 h) between the morning and evening milkings. Still abrupt weaning stresses both cows and calves even if CCC has been restricted before separation.     

Influence of parity on follicular dynamics and resumption of ovarian cycle in postpartum dairy cows

The present study examined ovarian changes preceding the resumption of the ovarian cycle in postpartum dairy cows with different parities under similar body nutritional conditions. In postpartum primi- (n=6), bi- (n=4), and multiparous (n=6) Holstein dairy cows, ovarian ultrasonographic observations starting at 7 days after calving were performed every other day and then daily after the confirmation of clinical signs of oestrus for the detection of postpartum first ovulation. Blood samples were collected at the same time as ultrasonography and analyzed for oestradiol and progesterone to monitor ovarian activity. To evaluate the nutritional condition of the cows, body weight and body condition score (BCS, 1=emaciated to 5=obese) were measured weekly and blood samples for the analysis of glucose, insulin, and non-esterified fatty acid (NEFA) were collected at the same time until postpartum second ovulation. Dominant follicles (>8mm in diameter) of the first follicular wave were detected at 7 days after calving in all cows. The first wave follicle ovulated in five of six multiparous cows, whereas no first wave follicle ovulated in any of the primiparous cows. The days to first ovulation after calving in primiparous cows (31.8+/-8.3 days) were significantly greater (p<0.05) than those in multiparous cows (17.3+/-6.3 days), but were not significantly different from biparous cows (28.8+/-8.6 days). There was a significant relationship between parity and days to first ovulation after calving (p<0.05). BCS was maintained at a level of more than 2.5 during the postpartum period in all cows and there was no influence of parity on postpartum changes in BCS, glucose, insulin, or NEFA throughout the experiment. The present study demonstrated a negative relationship between parity and number of days from calving to first ovulation in dairy cows under similar body nutritional conditions. It is possible that the influence of parity on the resumption of ovarian cycle is modulated by the factors different from the nutrition-related changes during the postpartum period in dairy cows.     

Enterococcal and streptococcal species isolated from faeces of calves, young cattle and dairy cows

Faeces from non-ruminating calves were found to contain several species of enterococci: Enterococcus avium, Ent. cecorum, Ent. durans, Ent. faecalis, Ent. faecium and Ent. hirae. Enterococcus faecalis was the most frequent. Few of these animals carried streptococci.
Streptococcus bovis largely predominated in ruminating calves, young cattle and dairy cows. Other streptococci as well as enterococci were infrequent in dairy cows, but a variety of other streptococci and enterococci were found in the faeces of young ruminating animals.     

X chromosome effects and their interactions with mitochondrial effects

We report a simple and rapid method for detecting additive genetic variance due to X-linked loci in the absence of marker data for this chromosome. We examined the interaction of this method with an established method for detecting mitochondrial linkage (another source of sex-asymmetric genetic covariance). When applied to data from the Collaborative Study on the Genetics of Alcoholism, this method found evidence of X-chromosomal linkage for one continuous trait (ntth1) and one discrete trait (SPENT). Evidence of mitochondrial contribution was found for one discrete trait (CRAVING) and three continuous traits (ln(CIGPKYR), ecb21, and tth1). Results for ntth1 suggest that methods that do not also allow for male-female heterogeneity in environmental variance may be overly conservative in detection of X-chromosomal effects.     

Effect of lactation trimester and parity on eating behavior,milk production and efficiency traits of dairy cows

There is absence knowledge about the effects of lactation trimester and parity on eating behavior, production and efficiency of dairy cows. Objective of this study was to identify and characterize in 340 dairy cows, the 20% high efficient (HE), 20% low efficient (LE) and 60% mid efficient (ME) cows according to their individual residual feed intake (RFI) values, within and between lactation trimesters and between 1st and 2nd parities. Efficiency effect within each lactation trimester, was exhibited in daily dry matter intake (DMI), eating rate and meal size, that were the highest in LE cows, moderate in the ME cows and lowest in the HE group. Daily eating time, meal frequency, yields of milk and energy-corrected milk (ECM) and BW were similar in the three efficiency groups within each trimester. The lower efficiency of the LE cows in each trimester attributes to their larger metabolic energy intake, heat production and energy losses. In subgroup of 52 multiparous cows examined along their 1st and 2nd trimesters, milk and ECM production, DMI, eating behavior and efficiency traits were similar with high Pearson’s correlation (r=0.78 to 0.89) between trimesters. In another subgroup of 42 multiparous cows measured at their 2nd and 3rd trimesters, milk and ECM yield, DMI and eating time were reduced (P<0.01) at the 3rd trimester, but eating rate, meal frequency and meal size remained similar with high Pearson’s correlation (r=0.74 to 0.88) between trimesters. In subgroup of 26 cows measured in 1st and 2nd parities, DMI, BW, milk and ECM yield, and ECM/DMI increased in the 2nd lactation, but eating behavior and RFI traits were similar in both parities. These findings encourage accurate prediction of DMI based on a model that includes eating behavior parameters, together with individual measurement of ECM production. This can be further used to identify HE cows in commercial herd, a step necessary for potential genetic selection program aimed to improve herd efficiency.     

Enterococcal and streptococcal species isolated from faeces of calves, young cattle and dairy cows.

Faeces from non-ruminating calves were found to contain several species of enterococci: Enterococcus avium, Ent. cecorum, Ent. durans, Ent. faecalis, Ent. faecium and Ent. hirae. Enterococcus faecalis was the most frequent. Few of these animals carried streptococci. Streptococcus bovis largely predominated in ruminating calves, young cattle and dairy cows. Other streptococci as well as enterococci were infrequent in dairy cows, but a variety of other streptococci and enterococci were found in the faeces of young ruminating animals.     

Characteristics of the electrolyte balance of the blood of healthy newborn calves and calves with diarrhea

Cows and newborn (just after the birth, and on the 1st, 3rd, 5th and 10th days after it) calves were tested for the peculiarities of the electrolyte blood composition and acid-base balance under normal and diarrheic conditions. The values of Na+/K+, Cl-/HCO3-, Pn/Ca2+ ratios in the blood serum of sick animals remain unchanged, which testifies to the deep disturbances of the water-salt metabolism in tissues.     

Free radicals, lipid peroxidation and the antioxidant system in the blood of cows and newborn calves around calving

The oxidative stress of birth in cattle (Bos taurus) was evaluated by measuring steady state concentration of free radicals in whole blood, rate of lipid peroxidation and activity of antioxidant enzymes in erythrocytes, antioxidant capacity of blood plasma in 14 calves at birth and four times after birth until 3 weeks of age and also in their mothers at calving. The same parameters were also measured in 58 dairy cows before calving, at parturition and after calving. Free radical concentration in the blood of newborn calves was higher than in cows confirming that birth means oxidative stress for calves. Red blood cell malondialdehyde in calves was the highest at birth and following the first solid feed intake at the third week. Superoxide dismutase activity increased in calves during the first three weeks of life. Ferric reducing ability of plasma was higher in calves at birth than in cows and decreased thereafter. Higher superoxide dismutase activity in red blood cells and lower ferric reducing ability of plasma in dairy cows was found at calving compared to the average of all pre- and post-calving results. We conclude that the blood of newborn calves is well prepared to deal with the oxidative stress of birth, and that such a stress is present even when some fingerprint markers of redox imbalance show no apparent alterations. Stress of calving has minor effects on the antioxidant system of cows.     

The effects of ovarian function on estrus synchronization with PGF in dairy cows

Milk progesterone concentration (P4), milk yield, milk composition, ovarian structures and pregnancy status were studied in 108 cows treated with two doses of PGF 14 days apart and inseminated at fixed time (TAI) 80-82 h later. The synchronization protocol was started at 70+/-1.4 days after parturition. Milk P4 profiles revealed that anestrus, failure of luteolysis following treatment with PGF and failure to ovulate following luteolysis were the main reasons for low pregnancy rate with TAI. Anestrous cows had a higher percentage of milk fat (P<0.05) and higher fat to protein ratio (P<0.01), and cows that did not undergo luteolysis had higher milk yield (P<0.05) and lower percentage of milk protein (P<0.05) than cows that responded to PGF treatment. Cows that did not undergo luteolysis and cows that did not ovulate following luteolysis had lower milk P4 during the luteal phase preceding the second PGF injection (P<0.01 and P<0.05, respectively). Pregnancy rates 24 and 47 days after TAI in cows that responded as expected to the synchronization treatment were 62% and 54%, respectively. Pregnancy was precluded in non-responsive cows. The largest follicle at the time of TAI in cows experiencing late embryonic mortality was smaller (P=0.02) than in cows that successfully maintained pregnancy. Results suggest that a primary reason for low pregnancy rate in dairy cows after administration of PGF and TAI is inappropriate ovarian function prior to, or following treatment.     

Prevalence of endometritis and its effects on reproductive performance of dairy cows

Hostein cows (n=141) in five commercial dairy herds in central New York were examined for endometritis by examination of endometrial aspirates for presence of inflammatory cells, principally neutrophils, by endometrial cytology at 40-60 days postpartum. The prevalence of cytologically-diagnosed endometritis was 53%; within herds the prevalence varied from 37 to 74% (P=0.02). There was excellent agreement between two examiners (Kappa=0.864; P<0.0001). Parity did not influence prevalence of endometritis (P=0.53). Cytologically diagnosed endometritis was associated with profoundly impaired reproductive performance; Kaplan-Meier survival analysis revealed lower overall pregnancy rate (P<0.0001). Median days open was 206 for cows with endometritis and 118 for cows free of the condition. Overall, 76% of cows in this study became pregnant by 300 days postpartum; 63% of cows with endometritis and 89% of cows without endometritis were confirmed pregnant by 300 days postpartum (P<0.003). (For these two groups, 69, and 90% respectively, became pregnant during the duration of the study). Pregnancy to first service percentage was lower (11 versus 36%; P=0.001) for cows with than without endometritis, and these cows required more services before 50% became pregnant (3 versus 2; P=0.006). In a second study using 22 cows in a university-owned herd, the prevalence of cytological evidence of inflammation was 100% at 2 weeks postpartum, and dropped to 89, 58, and 41% at 4, 6, and 8 weeks, respectively. Endometritis diagnosed by endometrial cytology late in the voluntary waiting period was highly prevalent and exerted a profoundly detrimental effect on subsequent reproductive performance, making this condition potentially extremely costly to the North American dairy industry.     

Liquid supplementation of grazing cows and calves

One hundred and one Angus cows (average weight 614 kg) and their bull calves (average weight 213 kg) grazing improved summer pastures were used to determine cow and calf intake of liquid supplement, and its effect on forage intake and performance. Forty-seven pairs had access to a 410 g CP/kg DM molasses-based liquid supplement in an open feeder and 54 pairs were not supplemented. The study was conducted in southwestern Montana from July 28 to October 3, 1997. Cows consumed significantly more supplement (0.3 kg/day) than calves (0.1 kg/day) but both consumed 0.5 g/kg bodyweight per day. Supplemented cows gained 0.12 kg/day more (p<0.05) than unsupplemented cows; however, there was no difference (p>0.10) in body condition score change. Average daily gain by supplemented calves was 30% greater (p<0.01) than average daily gain by unsupplemented calves. Forage intake (g/kg body weight) by both supplemented cows and calves was 64% greater (p<0.01) than forage intake by unsupplemented cows and calves. There was no difference (p>0.10) in milk intake between supplemented and unsupplemented calves. There was no difference (p>0.10) in time spent at the supplement feeder between cows and calves, averaging 5.0 min/day. Time at the feeder was lowest for 7-year-old cows, intermediate for 6- and 8-year-old cows, and highest for 9-year-old cows (p<0.10). There was no difference (p>0.10) in supplement feeding bouts/day between age groups of cows. Calf liquid supplement intake (g/kg body weight) and time spent at the supplement feeder were similar to intake and time spent at the feeder by cows. Liquid supplementation increased forage intake and average daily gain by cows and calves grazing improved forages in late summer. The cost for additional weight gained by the supplemented calves was US$ 0.33/kg and October cattle prices in Montana were US$ 1.64/kg. Liquid supplementation was cost effective under the conditions of this study.     

Behaviour of free-ranging beef cows and calves

The aim of this project was to describe the behaviour of free-ranging cows and calves after birth and during growth to the age of 6 months. Ten bull and 10 heifer calves were followed from birth until first suckling. Calves were observed to record their position in the field once a day until 10 days of age. Focal observations of 5 bull and 5 heifer calves were made from 27 to 167 days of age.

Of the cows studied, 2 separated completely from the herd at calving. The calving sites were randomly distributed in the area available. After birth all cows licked their calves. The amount of licking between 0 and 30 min was significantly greater than that between 30 and 60 min after birth. The duration of the first suckling was significantly longer for heifer calves than for bull calves. Eleven of 17 calves changed area during the first day after birth. The duration of cows licking calves did not change significantly from 27 to 167 days of age, and was not correlated to duration of licking immediately after birth. Suckling frequency per hour, suckling time per hour and duration of each suckling did not change significantly from 27 to 167 days of age. Bull calves from 27 to 167 days of age had a significantly higher frequency than heifer calves of sniffings towards adult cows other than the mother and a significantly higher frequency of mountings of adult cows. Cows and calves spent more time together when the calf was a female than when it was a male, and more time when the weaning weight was low than when it was high.     

Cloning of calves from various somatic cell types of male and female adult, newborn and fetal cows

Twenty-four calves were cloned from six somatic cell types of female and male adult, newborn and fetal cows. The clones were derived from female cumulus (n = 3), oviduct (n = 2) and uterine (n = 2) cells, female and male skin cells (n = 10), and male ear (n = 5) and liver (n = 2) cells. On the basis of the number of cloned embryos transferred (n = 172) to surrogate cows, the overall rate of success was 14%, but based on the number of surrogate mothers that became pregnant (n = 50), the success rate was 48%. Cell nuclei from uterus, ear and liver cells, which have not been tested previously, developed into newborn calves after nuclear transfer into enucleated oocytes. To date, seven female and six male calves have survived: six of the females were from adult cells (cumulus (n = 3), oviduct (n = 2) and skin (n = 1) cells) and one was from newborn skin cells, whereas the male calves were derived from adult ear cells (n = 3), newborn liver and skin cells (n = 2), and fetal cells (n = 1). Clones derived from adult cells frequently aborted in the later stages of pregnancy and calves developing to term showed a higher number of abnormalities than did those derived from newborn or fetal cells. The telomeric DNA lengths in the ear cells of three male calves cloned from the ear cells of a bull aged 10 years were similar to those of the original bull. However, the telomeric DNA lengths from the white blood cells of the clones, although similar to those in an age-matched control, were shorter than those of the original bull, which indicates that telomeric shortening varies among tissues.