AGE AND LENGTH AT WEANING AND DEVELOPMENT OF DIET OF PANTROPICAL SPOTTED DOLPHINS, STENELLA ATTENUATA, FROM THE EASTERN TROPICAL PACIFIC

Using stomach contents from 203 spotted dolphins ( Stenella attenuata ) killed in the yellowfin tuna fishery, we modeled the weaning process of calves. Spotted dolphins began to take solid food at approximately 6 mo of age, or 115 cm, but continued to suckle until they were nearly 2 yr old. Calves tended to feed more frequently on squid as they got older, which suggested there was a shift in diet during weaning. The average age and total body length at weaning was estimated to be 0.8 yr (approximately 9 mo) and 122 cm. The oldest suckling calf was almost 2 yr old, which suggests that some calves continued to suckle for more than a year after they could have been weaned. A better understanding of the weaning process, especially quantifying the period of time when calves are nutritionally dependent on their mothers may lead to a better evaluation of their potential vulnerability to the disturbance caused by the yellowfin tuna purse-seine fishery.     

Sexual maturity and estimated fecundity in female Indo‐Pacific bottlenose dolphins (Tursiops aduncus) from South Australia: Combining field observations and postmortem results

Knowledge of life history of bottlenose dolphins in Australia is limited, with no studies comparing field and postmortem data from the same region. Carcasses of 88 opportunistically collected females (1987–2015) were studied, including eight observed for up to 23 yr before death. Ovaries were weighed and number of corpora determined grossly. Nineteen mammary glands were examined histologically. Relative age was determined using developmental features and body length, estimated age by tooth incremental lines, and physical maturity by epiphyseal fusion. Age at sexual maturation was 7.17 yr (6–>14 yr) at body lengths of 191–209 cm. Physical maturation occurred at 12–17 yr, and body lengths of 195–233 cm. An Exponential model provided the best fit for age at body length, with an asymptote at 214 cm. Combined ovary weight increased between birth and sexual maturation, with significantly more corpora in the left ovary. Corpora increased with age and appeared to persist throughout life. For mature females, 95% had ≤ 11 corpora. Number of corpora was consistent with number of calves for females with known life histories. Estimated interbirth period was about 4 yr. Three females with abnormal reproductive features were either chronically diseased and/or had high heavy metal burdens.     

Estimates of (co)variance components due to direct and maternal effects for body weights in Jamunapari goats

Estimates of (co)variance components were obtained for weights at birth, weaning and at 6, 9 and 12 months of age in Jamunapari goats maintained at the Central Institute for Research on Goats, Makhdoom, Mathura, India, over a period of 23 years (1982 to 2004). Records of 4301 kids descended from 204 sires and 1233 does were used in the study. Analyses were carried out by restricted maximum likelihood (REML), fitting an animal model and ignoring or including maternal genetic or permanent environmental effects. Six different animal models were fitted for all traits. The best model was chosen after testing the improvement of the log-likelihood values. Direct heritability estimates were inflated substantially for all traits when maternal effects were ignored. Heritability estimates for weights at birth, weaning and at 6, 9 and 12 months of age were 0.12, 0.18, 0.13, 0.17 and 0.21, respectively. Maternal heritability of body weight declined from 0.19 at birth to 0.08 at weaning and was near zero and not significant thereafter. Estimates of the fraction of variance due to maternal permanent environmental effects were 0.09, 0.13 and 0.10 for body weights at weaning, 6 months and 9 months of age, respectively. Results suggest that maternal additive effects were important only in the early stages of growth, whereas a permanent environmental maternal effect existed from weaning to 9 months of age. These results indicate that modest rates of genetic progress appear possible for all weights.     

Life history of harbor porpoises (Phocoena phocoena) in Scottish (UK) waters

Life history parameters were determined for stranded and bycaught harbor porpoises (Phocoena phocoena) from Scottish (UK) waters (1992–2005). Fetal growth rate was 84.4 mm/mo and mean size at birth was 76.4 cm (range 65–88 cm). Males and females had a similar range of body lengths (65–170 cm and 66–173 cm, respectively), although asymptotic lengths were higher in females than males (approximately 158 cm and 147 cm, respectively). Nonpregnant females were significantly lighter, in relation to their length than males. Maximum estimated age was 20 yr for both sexes. Age at sexual maturity (ASM) was estimated as 4.35 yr in females and 5.00 yr in males. Conception occurred mainly in July and August although reproductively active males were recorded during April to July. Gestation lasted 10–11 mo, with calving mainly between May and July. Lactating females were recorded during June to November, while small calves with solid food in their stomachs were found mainly during February to May. Estimated pregnancy rate (0.34–0.40) is lower than recorded elsewhere, but is likely underestimated due to the prevalence of mature females of poor health status in the sample. Nevertheless, cetacean strandings can be an essential source of data on demographic parameters.     

Life history of the Indo‐Pacific humpback dolphin in the Pearl River Estuary,southern China

We studied life history characteristics of the Hong Kong/Pearl River Estuary population of Indo‐Pacific humpback dolphins (Sousa chinensis), based on data from 120 specimens stranded between 1995 and 2009, 40 individuals biopsied at sea, and a long‐term (14+ yr) photo‐identification study. Ages were determined for 112 specimens by thin‐sectioning teeth and counting growth layer groups. Estimated length at birth was 101 cm. Longevity was at least 38 yr, and there was little difference in growth patterns of males and females. Growth was described by a Bayesian two‐phase Gompertz model; asymptotic length was reached at 249 cm. The tooth pulp cavity filled at an average of 18.5 yr of age. Physical maturity was reached at between 14 and 17 yr of age, apparently a few years after attainment of sexual maturity. Maximum lengths and weights of about 268 cm and 240 kg were attained. Females appear to lose all their spots by 30 yr, although males may retain some spotting throughout life. Calving occurred throughout the year, with a broad peak from March to June. Of 60 females monitored at sea for >14 yr of the study, none were documented to have more than three calves, suggestive of low reproductive output or low calf survival.     

Offspring Grazing and Suckling Rates in a Sexually Dimorphic Ungulate with Biased Maternal Investment (Ammotragus lervia)

An analysis of resource gain is provided for Ammotragus calves during their first year of age. Both grazing and suckling rates are analysed and potential effects caused by age, sex, mother's rank and weaning period studied. During their first day of life, calves devote their time mainly to suckling, grazing starting at the second week of age and exceeding suckling rate from the fourth week onwards. When suckling rate reaches a significant decrease (at 2 mo), male calves show a significantly higher grazing rate than female calves, suggesting a higher energetic demand for males at this age. When calves are 1 mo old, sons of high-ranking mothers devote less time grazing than those of low-ranking ones, which is in accordance with the higher maternal investment they receive. Grazing rate shows distinctive values for the different weaning periods distinguished in this species, but the resumption of mothers' sexual activity, when a mother–offspring conflict occurs, does not affect grazing behaviour. These results are consistent with the biased maternal investment recently found in the same study population but focusing on another aspect, i.e. grazing behaviour, which is determined by calves' own decisions.     

Post-partum reproduction in swamp buffalo cows at two feeding levels

Post-partum progesterone secretion, oestrus, and conception were monitored in two groups of eight swamp buffalo cows which were fed at “low” or “high” levels from 12 weeks before until 36 weeks after calving. Calf birth weights and pre-weaning mortality were not affected significantly by nutritional treatment, but the average growth rates of calves from birth to weaning at 26 weeks of age were greater (P<0.01) at the high (0.39 kg/day) than at the low (0.26 kg/day) feeding level. In five cows from each group which reared calves to weaning, average post-partum intervals to first oestrus were 190 and 144 days (P<0.10), and average post-partum intervals to conception were 222 and 169 days (P<0.05), at the low and high feeding levels, respectively. Plasma progesterone profiles indicated that normal post-partum luteal function at both feeding levels was commonly preceded by transient corpora lutea with subnormal progesterone secretion. Mean body weights at conception did not differ significantly between the two groups, suggesting that earlier post-partum conception in cows at the high feeding level was associated with their lower body weight loss and/or their faster body weight recovery after calving.     

Effect of age at weaning on the physiological stress response and temperament of two beef cattle breeds

The study was conducted to evaluate the effect of age at weaning and breed on the stress response of calves to weaning and their temperament. At calving, 14 Parda de Montaña calves and 14 Pirenaica calves were randomly assigned to either early weaning (at 90 days) or traditional weaning (at 150 days) treatment. During nursing, calves were allowed to suckle their dams twice a day for 30 min. After weaning, calves were placed in an adjacent barn without access to their dams, where they remained for 7 days. On day 8 after weaning, they were transported to a feedlot where they received an intensive diet. Blood samples were taken 168 h before weaning (baseline) and 6, 24, 48 and 168 h after weaning for cortisol, fibrinogen and haematology analyses, and temperament was measured 90 and 180 days after weaning with the flight speed test. Cortisol concentration increased after weaning, irrespective of age at weaning. Early-weaned calves had a lower fibrinogen baseline and a greater increase in fibrinogen concentrations 48 h after weaning than traditionally weaned calves. Moreover, fibrinogen concentration returned to baseline values 168 h after weaning in traditionally weaned calves, whereas it remained high in early-weaned calves. Concerning breed effects, Pirenaica calves had higher cortisol concentration and fibrinogen increments after weaning than Parda de Montaña calves. Slight alterations occurred after weaning in haematology, but all parameters returned to baseline values 168 h after weaning, with no significant effects of age at weaning or breed. Despite the absence of clinical signs, early-weaned calves of both breeds suffered marginal anaemia, according to haemoglobin values. Regardless of age at weaning, Pirenaica calves had greater reactivity to human presence than Parda de Montaña calves, according to their higher flight speed values measured. Finally, early-weaned calves were lighter than traditionally weaned calves at weaning, but had similar weight gains in the feedlot. Consequently, they needed an additional 40 days to reach the target weight, irrespective of breed. Therefore, age at weaning had no major effects on the stress response to weaning or temperament, but early weaning increased the length of the feedlot period. On the other hand, Pirenaica calves were more reactive than Parda de Montaña calves to the stress of weaning and human presence.     

Morphometrics,body condition,and growth of the ringed seal (Pusa hispida saimensis) in Lake Saimaa: Implications for conservation

Morphometrics and growth of the critically endangered Saimaa ringed seal (Pusa hispida saimensis), which inhabits a freshwater lake in Finland were studied using data from 344 carcasses. This study presents the first detailed information on ringed seal pup growth and body condition from birth to the age of one year. Newborn pups were on average 68 cm long and weighed 5 kg. Pups attained the majority of their first year growth during the nursing period. Body condition and growth declined after weaning, but pups recovered from postweaning nutritional deprivation at the age of 8 mo. The seals achieved their maximum body length, girth, and mandible size around the age of 4 yr, and asymptotic body mass two years later. Baculum growth indicated that males reached sexual maturity at age 5–6 yr. The Saimaa ringed seals' asymptotic body length and mass were 132 cm and 59 kg, respectively, which is similar to medium sized marine ringed seals. Saimaa ringed seals' survival to adulthood is extremely low due to high bycatch mortality; furthermore climate change may hamper pup growth and elevate mortality. Therefore we recommend continuation of fishing closures to improve pup survival.     

Demography,female life history,and reproductive profiles among the chimpanzees of Mahale

Demography provides critical data to increase our understanding of the evolution, ecology, and conservation of primate populations. The chimpanzees of the Mahale Mountains National Park, Tanzania, have been studied for more than 34 yr on the basis of individual identification and standardized attendance records. From this long-term study, we derived the following demographic data: The major cause of death was disease (48%), followed by senescence (24%) and within-species aggression (16%). Fifty percent of Mahale chimpanzees died before weaning. The median ages of female life history variables were: first maximal swelling, 10.0 yr (n = 5); emigration, 11.0 yr (n = 11); and first birth, 13.1 yr (n = 5). The median period of adolescent infertility was 2.8 yr (n = 4) when calculated from the age at immigration to that at first birth. Female fecundity was highest between 20 and 35 yr of age, with an annual birth rate of 0.2. Twenty-six females that were observed from a young age (10-13 yr) to death at various ages (15-40 yr) gave birth to an average of 3.9 and weaned an average of 1.4 offspring. Twenty-five females that were observed from middle age (18-33 yr) to death in older age (31-48) gave birth to an average of 2.7 and weaned an average of 2.0 offspring. The post-reproductive lifespan for female chimpanzees was defined as the number of years that passed from the year when the last offspring was born to the year when the female died, minus 5. Twenty-five percent of old females had a post-reproductive lifespan. The interbirth interval after the birth of a son (x = 72 mo) tended to be longer than that after the birth of a daughter (x = 66 mo). The extent of female transfer, which is a rule in chimpanzees, is influenced by the size and composition of the unit group and size of the overall local community.     

Reproduction in Brahman cows calving for the first time at two or three years of age

A comparison of the subsequent reproduction of heifers that calved for the first time at 2 vs. 3 yr of age was conducted on a purebred Brahman herd from 1971 to 1978 in central Florida. Pregnancy rate, birth rate and weaning rate were obtained on 1,612 animals. Sire of the cow had a significant effect on all three reproduction traits, indicating possible genetic differences in these important traits. Age at first calving (either 2 or 3 yr) had no significant effect on overall reproduction rates; however, subsequent pregnancy and weaning rate was 4% higher in females calving first at 2 yr of age. Thirty-eight percent of the females that became pregnant at 15 to 17 mo of age, weighed 650 to 700 lbs. These heifers had been born early in the previous calving season. It is suggested that Brahmans can be selected to calve at 2 yr of age if good nutrition and management are provided.     

Growth rates of Antarctic fur seal Arctocephalus gazella pups at South Georgia

Large numbers of pups of the Antarctic fur seal were weighed at regular intervals through their rearing period in six seasons between 1972 and 1981 at South Georgia. Growth rates and birth and weaning weights were estimated from linear regressions of mean weight on mean age. Female pups had significantly lower growth rates and weaning weights than males, but higher variances for all growth parameters. This may reflect the importance to males of polygynous species of attaining high body weight. Except for an inverse relation between growth rate and birth weight there were no systematic relationships between growth parameters. Seasonal differences in growth rates were substantial and there was no indication that the continuing rapid population increase was affecting pup growth rates. The use of these data in detecting seasonal variations in local food availability is discussed. Preliminary estimates of the energy costs of pup rearing indicate that pup existence metabolism consumes c. 80% and mass gain to weaning only c. 15% of the energy provided by the female.     

Effect of pre-weaning feeding regimens on post-weaning growth performance of Sahiwal calves

The objective of the study was to assess the post-weaning growth response of Sahiwal calves reared on four different pre-weaning dietary regimens. The four diets were: (a) whole cow's milk, starter ration (SR; CP = 20%, total digestible nutrients (TDN) = 72%) and Berseem hay (H; Egyptian clover; CP = 21%, TDN = 63%); (b) whole cow's milk + H; (c) milk replacer (MR; reconstituted to supplier specification; Sprayfo®) + SR + H; and (d) MR + H. The protein and fat percentages of reconstituted MR were 2.22 and 1.84, respectively. Milk or MR were fed at the rate of 10% of the calves’ body weight (BW) until 56 days of age, and then withdrawn gradually until weaned completely by 84 days of age. The average initial BW of calves in groups A, B, C and D were 56.3 ± 1.0, 47.5 ± 1.0, 40.4 ± 1.0 and 30.3 ± 1.0 kg, respectively. Initially, there were 12 calves in each group with six of each sex; however, one male calf died from each of groups B and C and were not replaced. During the post-weaning period, 13 to 24 weeks, the calves were fed a single total mixed ration ad libitum based on maize, canola meal, wheat straw and molasses containing 16% CP and 70% TDN. Daily feed intake and weekly BW gains were recorded. The data were analyzed by MIXED model analysis procedures using the statistical program SAS. The intake of calves as percent of their BW, feed conversion ratio and cost per kg of BW gain were not different (P > 0.05) across treatments. The daily gain at 24 weeks of age for the pre-weaning treatments A, B, C and D were 746 ± 33, 660 ± 33, 654 ± 33 and 527 ± 33 g/day and the final liveweights of calves were 119 ± 4.2, 102 ± 4.2, 95 ± 4.2 and 75 ± 4.2 kg, respectively. Gains were influenced significantly (P < 0.05) by pre-weaning treatments. The calves fed MR and H only during the pre-weaning period were unable to catch up post weaning with calves on other dietary treatments. The calves fed whole milk from birth at the rate of 10% of liveweight together with concentrates had higher weaning weight and superior growth rate post weaning as well. Thus, pre-weaning feeding was important for higher weaning weights and superior growth rates post weaning.     

Testicular size at weaning in tropically-adapted beef bulls as influenced by breed of sire and dam

This study was conducted to evaluate testicular size at weaning for bulls representing diverse tropically-adapted genotypes. Calves from 2 locations were weighed and castrated at weaning. In one herd, calves were born to Brahman dams and Angus, Tuli, and Brahman sires. Body weights and paired testes weights were heavier (P < 0.01) for Angus x Brahman (AB) genotype than for Tuli x Brahman (TB) and purebred Brahman (BB) genotype calves. The testes:body weight ratio was greater (P < 0.01) for AB than for TB and BB calves. In a second herd, calves were born to Angus cows and Brahman, Tuli, and Senepol sires. Means were similar between Brahman- (BA), Tuli-(TA), and Senepol-sired (SA) calves for body weight and testes:body weight ratio. Paired testes weight was heavier (P < 0.05) for SA than BA calves. Across locations, paired testes weights were heavier (P < 0.01) for TA than TB calves but their body weights were similar. Within-herd deviations were greater (P < 0.01) for AB than BA calves for paired testes weight and testes:body weight ratio. The correlation between the proportion of Bos indicus genetic contribution and testes:body weight ratio was significantly negative. Tropically-adapted calves differed in testicular size at weaning due to breed of sire and dam effects.     

Clinical and pathologic features of cloned transgenic calves and fetuses (13 case studies)

The neonatal abnormalities, treatments and outcomes in a group of 13 cloned transgenic calves and fetuses that progressed into the third trimester of pregnancy are described. From these 13 fetuses, 8 calves were born live, 4 stillborn fetuses were recovered from 3 cows that died 7 d to 2 mo before term, and 1 aborted fetus was recovered at 8 mo gestation. All fetuses and calves were derived from the same male fetal Holstein fibroblast cell line transfected with a beta-galactosidase marker gene. Six calves were delivered by Cesarian section and two by vaginal delivery between 278 and 288 d of gestation. Birth weights ranged from 44 to 58.6 kg. Five of the 8 live born calves were judged to be normal within 4 h of birth based on clinical signs and blood gas measurements. One of these 5 calves died at 6 wk of age from a suspected dilated cardiomyopathy. Three of the 8 calves were diagnosed with neonatal respiratory distress immediately following birth, one of which died (at 4 d of age) as a result of pulmonary surfactant deficiency coupled with pulmonary hypertension and elevated systemic venous pressures. Similar findings of chronic pulmonary hypertension were also observed in 2 of 5 fetuses. Placental edema was present in both calves that later died and in the 2 fetuses with cardiopulmonary abnormalities. Hydrallantois occurred with or without placental edema in 6 cows, and only 1 calf from this group survived. The 6 cows without hydrallantois or placental edema produced 5 live calves and 1 aborted fetus. The cardiopulmonary abnormalities observed in the calves and fetuses occurred in utero in conjunction with placental abnormalities, and it is likely that the cloning technique and/or in vitro embryo culture conditions contributed to these abnormalities, although the mechanism remains to be determined.     

BODY WEIGHT and GROWTH OF JUVENILE MALE NORTHERN FUR SEALS, CALLORHINUS URSINUS

A mark-recapture study conducted in 1987–1992 provided weight measurements of juvenile male northern fur seals ( Callorhinus ursinus ) on St. Paul Island, Alaska, at ages ranging from approximately 1.5 mo to 5 yr. Males born in 1987 tended to weigh less at ages 3 and 4 yr than those born in other years. Weights of individuals at ages 2, 3, and 4 yr were significantly correlated with their weights as pups ( P < 0.05). Weights at ages 2 and 3, 3 and 4, and 4 and 5 yr were significantly correlated ( P < 0.001), although weight changes with age were highly variable. Data indicate that larger than average male pups born during 1987–1990 were more likely to survive, but this effect was less evident than among pups born during 1960–1965 when average pup weights were lower.     

Estimates of direct and maternal covariance functions for growth of Australian beef calves from birth to weaning

Records for birth and subsequent, monthly weights until weaning on beef calves of two breeds in a selection experiment were analysed fitting random regression models. Independent variables were orthogonal (Legendre) polynomials of age at weighing in days. Orders of polynomial fit up to 6 were considered. Analyses were carried out fitting sets of random regression coefficients due to animals'' direct and maternal, additive genetic and permanent environmental effects, with changes in variances due to temporary environmental effects modelled through a variance function, estimating up to 67 parameters. Results identified similar patterns of variation for both breeds, with maternal effects considerably more important in purebred Polled Herefords than a four-breed synthetic, the so-called Wokalups. Conversely, repeatabilities were higher for the latter. For both breeds, heritabilities decreased after birth, being lowest when maternal effects were most important around 100 days of age. Estimates at birth and weaning were consistent with previous, univariate results.     

Telomere lengths in cloned transgenic pigs

Studies of cloned cattle and mice have resulted in controversies regarding the restoration of eroded telomere length of donor cells by the nuclear transfer process. Little is known about telomere lengths in pigs from either natural reproduction or nuclear transfer. In this study, we measured the telomere lengths in six major porcine organs from animals of different ages, and found that their lengths remained consistent throughout different tissues during fetal stages, and then shortened, in a tissue- specific manner, after birth. Telomeres of skin samples from six cloned transgenic pigs at 4 mo of age did not differ significantly from those of age-matched controls. Two cloned pigs that died shortly after birth had skin telomere lengths equivalent to those of late-stage fetuses.     

Normal calves produced after transfer of in vitro fertilized embryos cultured with an antiviral compound

Bovine viral diarrhea virus (BVDV) replicates in embryo co-culture systems and remains associated with developing IVF bovine embryos, despite washing and trypsin treatment. Previous research demonstrated that 2-(4-[2-imidazolinyl]phenyl)-5-(4-methoxyphenyl)furan (DB606) inhibits replication of BVDV in cultured cells. The objective of this study was to evaluate the capability of IVF embryos to develop into normal, weaned calves after exposure to antiviral concentrations of DB606 during IVC. Oocytes were obtained from cows via transvaginal, ultrasound-guided follicular aspiration. Presumptive zygotes (n = 849) that resulted from fertilization of these oocytes were cultured for 7 d in medium supplemented with 0.4 microM DB606 or medium lacking antiviral agent. All blastocysts (n = 110) were transferred individually into the uterus of a synchronized recipient. The pregnancy status of recipients was determined using transrectal ultrasonography at 21-23 d after embryo transfer. Additional pregnancies as controls (n = 21) were initiated by natural breeding. Developing fetuses and resulting calves were evaluated every 27-34 d. Blastocyst development, pregnancies per transferred embryo, pregnancies maintained per pregnancies established, gestation length, gender ratio, birth weights, viability of neonates, complete blood counts, and serum chemistry profiles at 3 mo of age and adjusted 205 d weaning weights were compared for research treatments. Development to weaning after exposure to DB606 did not differ significantly from controls. In conclusion, bovine embryo cultures can be safely supplemented with antiviral concentrations of DB606; addition of DB606 agent might prevent viral transmission if BVDV were inadvertently introduced into the embryo culture system.     

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.