1st Breeding Research Articles

IS THIS PHILOPATRY OR DISPERSAL IN FEMALE BOREAL OWLS?

Four cases of female Boreal Owls (Aegolius funereus) recaptured within varying distances of their natal or breeding sites are reported. We considered 3 recaptures within the natal or breeding neighborhood to be philopatry (site fidelity), and 1 case as dispersal. One banded female was recaptured as a 2y old, 3.4 km from her natal box. We considered this philopatry. She was later recaptured 15.8 km from her 2nd breeding site, and we considered this breeding dispersal. She lived at least 5 y, but we did not know her whereabouts in all years. A 2nd female banded as a nestling was recaptured 2.0 km from her natal box, breeding as a yearling (11 mo). We considered this natal philopatry. A 3rd female, previously banded as a breeding adult, was recaptured 2 y later breeding 2.5 km from her initial site of banding. We considered this philopatry. She was at least 4 y old. The 4th female was recaptured 3.6 km from her initial breeding box. We considered this philopatry. She was recaptured again the following year in the same nest box as her 2nd nest site. We considered the use of this same nest site philopatry. She was in her 5th calendar year. Our records are perhaps the 1st reports of natal philopatry and age of 1st breeding for female Boreal Owls in North America, and contribute additional records of female site fidelity and dispersal.

OPTIMAL BREEDING AGE FOR THE WEST AFRICAN DWARF SHEEP IN IBADAN

Observations on the age at first breeding of West African Dwarf Sheep at the University of Ibadan. Nigeria showed that the optimal age and weight at 1st breeding of young ewes was not less than eleven months and at least 13kg respectively When mated earlier, the incidence of abortion in­creased and lambs tended to the smaller at birth. In ewes mated at older ages the lengthening of the generation internal was unacceptable. The relalionuship between weight (4 ) and age (X) from four to 56 weeks was estitnated as: Y (kg) = 3.12 + 9.62 x — 0.02 x 2 + 0.0002 x 3 for singles. or Y =2.59 + 0.46 x = 0.01 x2 + 0.0001 x 3 for Mins.

423 WS Young Scholar Talk MS II: Heat stress-induced deficits in growth, metabolic efficiency, and cardiovascular function coincided with chronic systemic inflammation and hypercatecholaminemia in ractopamine-supplemented feedlot lambs

Abstract Our 1st study evaluated the effects of □-adrenergic agonist (ractopamine) supplementation on growth, health, and wellbeing in heat-stressed feedlot wethers. Chronic heat stress impaired growth, metabolism, and wellbeing even when the impact of reduced feed intake was eliminated by pair-feeding. We observed systemic inflammation and hypercatecholaminemia that were likely mediators of these deficits. Moreover, ractopamine did not diminish any wellbeing indicators and improved muscle growth without worsening the effects of heat stress. Our 2nd study assessed the effects of pubertal cyclicity (weaning to 1st breeding) in cows on myoblast-mediated muscle growth, metabolism, and growth efficiency of their offspring. Maternal fertility and postnatal growth efficiency of offspring are imperative to successful beef cattle production. A maternal condition was previously identified in which cows exhibited irregular cyclicity patterns or were non-cyclic between weaning and 1st breeding. This condition is thought to be associated with high concentrations of androstenedione in their follicular fluid, which causes cows to be sub-fertile but also wean heavier calves when they do become pregnant. We hypothesized that calves from cows exhibiting irregular pubertal cyclicity would have enhanced growth efficiency compared to calves from cows with normal pubertal cyclicity. To test this hypothesis, we evaluated myoblast function, growth, and metabolism pre-weaning, as well as growth efficiency in the feedlot and carcass characteristics at harvest in calves from cows that were previously identified as having typical, start-stop, or non-cycling pubertal cyclicity patterns. Calves from irregular cycling cows had reductions in insulin sensitivity, plasma proteins and lipids paired with increased myoblast function and reduced myoblast glycolytic capacity. Data independently and combined suggest calves from cows with irregular cyclicity from weaning to 1st breeding have chronic inflammation. While the specific mechanism of inflammation is unknown, further research may allow mediators of abnormal cyclicity and offspring inflammation-induced dysfunction to be elucidated.

257 Beef cows with atypical estrous cyclicity at puberty produced calves with deficits in pre-weaning muscling, metabolic indicators, and myoblast function but not in feedlot performance

Abstract Economic beef production requires efficient growth. In our herd, cows were identified that exhibited irregular (start-stop) or absent (non-cyclic) pubertal estrous cyclicity prior to their 1st breeding season. These cows were sub-fertile but weaned heavier calves. Here, we determined if these calves possessed enhanced muscling and metabolic efficiency. Early muscle growth and metabolic indicators, feedlot performance, and carcass traits were evaluated in steer calves from cows that had exhibited normal (typical), start-stop, or non-cyclic pubertal estrous patterns. Start-stop and non-cyclic cows calved later (P < 0.05) than typical cows, but calf birthweights did not differ among groups. Weaning weights tended to be decreased (P = 0.09) in calves from start-stop and non-cyclic cows, but 205-d adjusted weaning weights did not differ. At 3 mo, body composition estimated by bioelectrical impedance revealed a tendency for reduced (P = 0.10) muscle mass in calves from non-cyclic and start-stop compared to typical cows. Plasma cholesterol, high-density lipoprotein, and triglyceride concentrations were reduced (P < 0.05) and glucose/insulin tended to be increased (P = 0.09) in calves from non-cyclic cows. Plasma urea nitrogen did not differ among groups. Ex vivo proliferation was greater (P < 0.05) for myoblasts isolated from calves of start-stop and non-cyclic compared to typical cows. Total oxidative metabolism did not differ but glycolysis was decreased (P < 0.05) in myoblasts from calves of non-cyclic cows. Feedlot average daily gain and dry matter intake did not differ during growing or finishing. Feed efficiency tended to be increased (P = 0.09) in calves from non-cyclic cows but not when normalized to dressing percentage. Hot carcass weight, dressing percentage, ribeye area, fat thickness, and marbling did not differ among groups. These findings indicate that atypical maternal estrous cyclicity at puberty reduced early muscle growth and metabolism in offspring but not feedlot growth or carcass merit. We speculate that early growth deficits are influenced by inflammatory changes.

PRODUCTIVE QUALITIES OF COWS OF DIFFERENT BREEDING GROUPS OF THE BUKOVINSKY FACTORY OF THE UKRAINIAN RED-AND-WHITE DAIRY BREED

The studies were conducted on the materials of the breeding record of the breeding plant of JSC "Mirne" of Chernivtsi region - the basic farm of the Bukovyna factory type of the Ukrainian red-speckled dairy breed. 360 cows were selected for analysis, based on live weight, yields, fat and protein content of milk, total milk fat and protein content.
 The intensification of dairy cattle breeding necessitates the systematic evaluation of animals in herds and populations on the basis of economically useful traits.
 Analysis of the productive qualities of the cows of the different breeding groups showed that, by live weight, milk yield, milk fat and protein content, the two-breed (II breeding group) animals were better than the three-breed (I breeding group). The difference for the first lactation was 11.2; 32.9; 1.5; 1.0 kg respectively. In cows with the second lactation, the pattern remained, the difference was 22.2; 395.8; 15.8; 13.1 kg respectively, and for the third lactation – 31.4; 124.3; 4.8; 4.2 kg. The fat and protein content of milk varied between 3.88–3.89% and 3.33–3.34%, respectively. It should be noted that in cows of both groups there was a decrease in milk milk yield with increasing number of lactations.An evaluation of the productive qualities of the first-born cows of the different lines showed that Marshall's first-borns were better in live weight, milk yield, milk fat and protein, although they were inferior to other lines in terms of fat and protein content. In the firstborn of the Hanover Red line, the estimated values were lower than in animals of other lines, in particular – by live weight by 11.4 kg, milk yield by 1115.2 kg, milk fat by 44.1 kg, milk protein by 37.2 kg (Chif line), by 5.4; 1336.5; 52.7; 45.2 kg (Starbuck line) and 14.7; 1465; 55.1; 48.3 kg (Marshall Line).The effectiveness of breeding for increasing dairy productivity of cows depends on the efficiency of selection and selection of animals, taking into account the phenotypic and genetic correlation between economically beneficial traits. It was found that the highest positive values of correlation coefficients were observed in the cows of the studied groups between milk yield and protein content in the context of all lactations – 1st breeding group (r = 0,12–0,25), 2 nd breeding group (r = 0.19–0.3). In the cows of the first breeding group for the first and second lactations revealed not high but positive correlation of milk yield with live weight (r = 0.33–0.49). In the cows of the second breeding group for the first and second lactation positive correlation with milk fat content was found.The first positive cows of different lines showed the highest positive values of the correlation coefficients between milking and protein content (r = 0.19–0.43). There was also a low positive correlation of milk yield with live weight in the firstborn of all evaluated lines (r = 0.03–0.09), as well as milk fat content in cows of Starbuck and Marshall lines.Conclusions. 1. By live weight, milk yield, milk fat and protein content, two-bovine cows of the Bukovyna factory type of Ukrainian red-speckled dairy breed were better than three-born. The fat and protein content of milk varied between 3.88–3.89% and 3.33–3.34%, respectively. In cows of both groups there was a decrease in milk yield with increasing number of lactations.2. By live weight, milk yield, milk fat and protein content, Marshall Line firsts were better, although they were inferior to other lines in terms of fat and protein content. In the firstborn of the Hanover Red line, the estimates were lower than in other line animals.3. The highest positive values of correlation coefficients were observed between milk yield and protein content in the context of all lactations in the cows of Bukovyna factory type of Ukrainian red-rippled dairy breed. In two breeds of cows for the first and second lactation revealed not high but positive correlation of milk yield with live weight, and in three breeds for the first and second lactation positive correlation of milk yield with fat content.

Relationship between Growth Pattern, Age at First Calving and Next Reproduction in Holstein Heifers

Growth rate during rearing, which varies depending on provided nutrition, has been related with age at 1st calving (AFC). This study investigated the effect of upgrowth parameters during the rearing period on the reproduction of nulliparous Holstein heifers. The study comprised 77 successively born heifers from the same herd. Growth rate and fertility traits were measured during rearing and fertility parameters were recorded in lactations 1. Growth parameters (body weight, height, heart girth and body length) were measured at the approximate birth time, 270 and 450 d of age. Reproduction data collected included age at 1st breeding, number of services per conception (S/C), pregnancy rate to 1st artificial insemination, AFC. Animals were subsequently divided into 4 AFC groups for analysis: 30 mo. The AFC reflected both upgrowth rate and heifer reproduction, with later calving heifers smaller. Increased skeletal growth (at 270 and 450 d) was related with a reduced AFC (p 30 mo). In the 1st lactation period, a number of services per conception (3.1±0.3) increased with increasing AFC (>30 mo). Sub-optimal upgrowth related with an increased AFC could be mitigated by improved monitoring of replacement heifers during the rearing period.

Reproductive Effects of Prolonged Experimentally Induced Hypothyroidism in Bitches

Hypothyroidism has detrimental effects on reproduction in females of many species. Studies of hypothyroidism in bitches are limited and results conflicting. Hypothyroidism interferes with reproductive function and health of offspring in bitches. A total of 9 healthy mixed-breed bitches (control) and 9 mixed breed bitches with hypothyroidism induced by radioactive iodine administration. Dogs in both groups were bred 20.9 ± 4.0 and 56 ± 7.6 weeks after radioiodine administration in the hypothyroid group and again after levothyroxine was administered for 37 ± 14 weeks to hypothyroid dogs. Measures of the estrus cycle, fertility, gestation, whelping, and pup health were evaluated at each breeding. Comparisons were made between hypothyroid and control dogs as well as within groups between times. Pregnancy was documented in all dogs in both groups at the 1st breeding, 4/8 and 6/6 untreated hypothyroid and control dogs, respectively, at the 2nd breeding, and 6/6 and 5/6 treated hypothyroid and control dogs, respectively, at the 3rd breeding. Periparturient mortality was higher and birth weight was lower in pups born to untreated hypothyroid dogs compared with control dogs or treated hypothyroid dogs. There was no difference in interestrus interval, gestation duration, breeding behavior, interval between birth of pups, or serum progesterone concentrations at any breeding between or within groups. Resolution of hypothyroidism reversed the detrimental effects of thyroid hormone deficiency on reproduction. Hypothyroidism causes reversible periparturient mortality and low birth weight in offspring. Further investigation is necessary to determine if fertility is affected.

Effects of environmental variability and breeding experience on northern elephant seal demography

Demographic rates of animals (i.e., survival and breeding success) generally increase with experience early in life, but temporal variation in the effect of experience on demography is not well understood. The demographic difference between inexperienced versus experienced breeders can be accentuated during poor environmental conditions when food is scarce, or the difference can remain constant regardless of environmental fluctuation. I tested the hypothesis that environmental variation accentuates the difference between inexperienced and experienced breeders using 20 years of capture–mark–recapture data for northern elephant seals (Mirounga angustirostris) from the Farallon Islands, California. I estimated year-specific survival probabilities, breeding propensity (the probability that an individual will breed in year x), and breeding success of primiparous (inexperienced) and multiparous (experienced) females. Primiparous breeders did not suffer more than experienced breeders during years of environmental stress. The selection hypothesis (a decrease in heterogeneity in individual quality within cohorts over time, based on selection pressure) could explain the experience-related improvement in survival and breeding success. Lower variances in survival of multiparous breeders suggest that primiparous adults constitute a more heterogeneous portion of the population, and the 1st breeding event might act as a selective process leading to a more homogeneous pool of multiparous breeders.

Rearing conditions and lifetime milk revenues in Swedish dairy cows

Associations between replacement heifer rearing conditions and lifetime milk revenues were studied throughout the productive life of Swedish dairy cows. Data were collected from 2127 cows, mainly Swedish Reds and Swedish Holsteins, representing all female animals born during 1998 in 110 herds and followed until May 2006. Lifetime net milk revenues were calculated for each cow based on the length of productive life, lifetime milk production, a fixed milk price of 0.3 €/kg ECM, and estimated costs for heifer rearing and cow feed. Median observed productive lifetime to culling, death, selling off or terminated recording was 26.9mo. Mean lifetime production was 9209kg ECM/cow-yr, calculated from monthly test-day yields. Rearing costs (median 631 €) were estimated using a template developed for Swedish advisory services, including costs related to purchase, feeding, labour, building investment, building maintenance and breeding. Net milk revenues had a median of 1169 €/cow-yr during productive life and were heavily skewed. Diarrhea and respiratory disease before 7mo of age had occurred in 11 and 11% of the cows, respectively, the majority cases being mild. The mean prepubertal growth rate was 670g/day. Cow net revenue values were transformed to achieve normality and analysed by a linear mixed model including fixed effects of breed, calf housing system from 3 to 7mo of age, body condition score at 1st breeding, year of 1st calving, age at 1st calving, cow housing system, mean milk cell count, the interaction between calf housing and breed, the interaction between cow housing and breed, and the random effect of herd. The model predicted net revenues to decrease with age at 1st calving and with body condition score at breeding over 4. Our results show that replacement rearing factors influence net milk revenues of a dairy operation and suggest that current recommendations to breed dairy heifers for calving at 24mo are economically justified.

The applications of timed artificial insemination and timed embryo transfer in reproductive management of dairy cattle

Fertility of dairy cattle is generally decreasing. Overall estrus detection efficiency in lactating dairy cattle is low, as expression of estrus is often compromised. Consequently, undetected estrus, low AI-submission rates, and long inter-breeding intervals are the main contributors to poor reproductive efficiency. Although failure to become pregnant is the most common reason for culling dairy cattle, pregnancy rates could be improved by increasing the AI-submission rate through increased estrus detection efficiency, timed insemination (Timed-AI), or timed embryo transfer (Timed-ET). In these protocols, ovarian follicular development and luteolysis are controlled, culminating in synchronous ovulation in most cows. There are several modifications to improve pregnancy rates in Timed-AI protocols, e.g. presynchronization with 2 doses of PGF2a 14 d apart, and starting the Ovsynch protocol 12 d after the 2nd PGF2a. Timed-AI programs ensure a timely first breeding; this should be followed with early pregnancy diagnosis to identify nonpregnant cows, and prompt re-insemination. However, in a recent field study involving 23 dairy herds, the mean interval between 1st and 2nd breeding was 42 d; only 28% of the cows were rebred within 24 d after 1st breeding. Fortunately, there are several resynchronization protocols to reduce inter-breeding intervals. Anestrus cows, or those with cystic ovarian follicles, have a good chance of conceiving when subjected to synchronization of ovulation and Timed-AI. Furthermore, Timed-ET is a practical and viable option for synchronizing and selecting recipient cattle for embryo transfers. In summary, systematic and judicious use of Timed-AI and Timed-ET protocols can greatly enhance reproductive performance, and improve herd productivity.

Rearing conditions, morbidity and breeding performance in dairy heifers in southwest Sweden

We carried out a longitudinal study of 122 dairy herds in southwest Sweden to investigate relationships of rearing conditions and health with heifer breeding performance and to estimate the incidence of clinical diseases and survival until 1st calving. A total of 3081 animals born in 1998 (47% Swedish Red; 50% Swedish Holstein breed) were followed from birth until calving, culling or death. Information about housing, management, breeds and dates of birth, breeding and calving was obtained from farmers. Diseases were recorded by farmers and veterinarians; antibiotic treatment was used in <25% of all cases. Median time to breeding was 17.5 months, 64% of all heifers bred by AI conceived at 1st breeding, and median time to calving was 27.6 months. Age at 1st breeding (log-transformed), conception at 1st breeding (binary), and age at 1st calving (log-transformed) were analysed with three mixed models, accounting for clustering by considering random-intercept and random-slope effects at the herd level. Around 40 potential predictors or confounders were recorded and considered for modelling. Time to breeding and calving increase greatly with the time heifers spend grazing, although up to 5 months of grazing before 1st calving appears to be more favourable than no grazing at all. The effect of grazing differs depending on the season of birth. Zero-grazed heifers calve 20% later if exposed to indoor ammonia concentrations >10 ppm after start of breeding. There is considerable variation between herds in breeding performance, except for conception at 1st breeding—limiting the potential for improving conception by herd measures. Observed total disease incidence rate was 14 per 100 animal-years from 7 months of age to estimated conception and 4.7 per 100 animal-years from conception to calving, with great variation between herds. Infectious diseases were predominant, and diarrhoea, respiratory disease and ringworm were the most common diagnoses. Eight hundred and fifty-three heifers left the study before calving, due to herd exits (incidence risk 0.073%), selling off live (0.061%), spontaneous deaths (0.050%) or slaughter (0.092%).

WHO SOLVED THE MYSTERY OF THE MARBLED MURRELET?

To determine which northwestern naturalists solved the mystery of where marbled murrelets (Brachyramphus marmoratus) nest, we reviewed all historical records of “breeding” (including nests, eggs, and chicks found at inland locations) to determine all 1st breeding records. The 1st breeding records were in coastal coniferous old-growth forests; the 1st inland chick was found without a nest (Minerva, Oregon—1918), and the 1st inland egg was found without a nest (Saxon, Washington—1925). The 1st confirmed record of a ground nest with an incubating adult was found above tree line at 580 m elevation (Chichagof Island, Alaska—1931). The 1st and 2nd confirmed records of old-growth tree nests were found near the ocean when a dead adult with a brood patch and broken eggshells were found amid a felled western hemlock (Tsuga heterophylla; Masset, British Columbia—1953) and 2 chicks fell to the ground during the felling of a western red cedar (Thuja plicata; Holberg, British Columbia—1967). We consider that the mystery was solved between 1918 and 1967 and collectively credit 1st breeding records to EJ Booth, W Feyer, RD Harris, AB Johnston, ER Osburn, and S Warburton Jr. We also identify other important findings that helped solve the mystery of the marbled murrelet including: 1st recorded observation of murrelets flying inland from the coast (Sitka, Alaska—1896); 1st shelled egg from an oviduct of an adult female collected at sea (Howkan, Alaska—1897); 1st recorded far-inland record of flying murrelets (Glacier, Washington—1905); 1st accepted well-described tree nest (Douglas-fir Pseudotsuga menziesii; Big Basin Redwoods State Park, California—1974); 1st accepted well-described ground nest (Barren Islands, Alaska—1978); 1st long-billed murrelet (B. perdix) probable ground nest (Komandorskiye Islands, Russia—about 1891); 1st long-billed murrelet confirmed tree nest (Okhotsk, Russia—1961); and 1st Kittlitz's murrelet (B. brevirostris) confirmed ground nest (Pavloff Mountain, Alaska—1913). Since the 1970s, solution of the mystery has continued with discoveries of the 1st confirmed cavity or crevice nest (Port Chatham, Alaska—1981), 1st confirmed cliff nest (Perry Island, Alaska—1989), and 1st confirmed nest in a deciduous tree (red alder Alnus rubra; Toba Inlet, British Columbia—2000).

Reproduction in female yaks ( Bos grunniens) and opportunities for improvement

This paper reviews seasonal breeding, puberty, postpartum anestrus, embryonic loss and calf survival and their constraints in female yaks. Methods for improving fertility in postpartum yak cows are also considered. Yaks are seasonal breeders with mating and conception restricted in the warm season. Puberty generally occurs in the 2nd to the 4th warm season following birth, i.e. between 13 and 36 months of age. The cows usually have a long postpartum anestrus period; only a small proportion of the cows return to estrus in the 1st breeding season after calving, most come into estrus in the 2nd and 3rd years. Nutritional status is the most important determinant of reproduction in female yaks. Reproductive success is a direct result of the availability of pasture determined by climate, season, and management practices. Milking delays puberty by reducing milk intake (restricted suckling) and growth rate for the calf. Milking interferes with grazing and prolongs the duration of postpartum acyclicity in cows. Calves born early in the season have a longer suckling season than those born later in the season before the onset of winter. Thus, they can have their first cycle in the breeding season of the following year, while those born late in the season may not have their first estrus until 25 or 26 months of age. Cows calving early in the season are more likely to return to estrus in the year of calving because they have a longer period to recover from the demand on body reserves before the onset of winter. Inbreeding in smallholder yak farms is also discussed and minimizing inbreeding by exchanging bulls among different herds is suggested. Reproductive efficiency can be improved by nutritional supplementation during the winter, however, the most cost-effective and practical strategy for this needs to be determined. Early weaning or restricted suckling may shorten the duration of postpartum acyclicity, however, it is impractical due to reduced growth rates and increased winter mortality of early weaned calves. A single treatment with either GnRH, or PGF 2α+GnRH can successfully induce estrus in yak cows that calved in previous years (with or without calf) but did not calve in the current year, however, it has little effect in cows nursing a calf born in the current year. The effects of administration of exogenous progestogens plus GnRH on the fertility of yak cows are worthy of further study.

Dispersal, Overwinter Mortality, and Recruitment of Spruce Grouse

Dispersal, Overwinter Mortality, and Recruitment of Spruce Grouse