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PubMed2004

Power of exclusion for parentage verification and probability of match for identity in American Kennel Club breeds using 17 canine microsatellite markers.

DNA analysis of microsatellite markers has become a common tool for verifying parentage in breed registries and identifying individual animals that are linked to a database or owner. Panels of markers have been developed in canines, but their utility across and within a wide range of breeds has not been reported. The American Kennel Club (AKC) authorized a study to determine the power to exclude non-parents and identify individuals using DNA genotypes of 17 microsatellite markers in two panels. Cheek swab samples were voluntarily collected at Parent Breed Club National Specialty dog shows and 9561 samples representing 108 breeds were collected, averaging 88.5 dogs per breed. The primary panel of 10 markers exceeded 99% power of exclusion for canine parentage verification of 61% of the breeds. In combination with the secondary panel of seven markers, 100% of the tested breeds exceeded 99% power of exclusion. The minimum probability match rate of the first panel was 3.6 x 10(-5) averaged across breeds, and with the addition of the second panel, the probability match rate was 3.2 x 10(-8); thus the probability of another random, unrelated dog with the same genotype is very low. The results of this analysis indicated that, on average, the primary panel meets the AKC's needs for routine parentage testing, but that a combination of 10-15 genetic markers from the two panels could yield a universal canine panel with enhanced processing efficiency, reliability and informativeness.

Animals↗
PubMed2001

Faecal oestrogens and progesterone metabolites in mares of different breeds during the last trimester of pregnancy.

Non-invasive pregnancy diagnosis in mares by measuring faecal oestrogens has been performed over years with great accuracy. However, results have indicated breed-related differences in the amount of excreted steroids during late pregnancy. Therefore faecal samples were collected during the last 4 months of pregnancy of Thoroughbred (n = 10), New Forest pony (n = 9), Shetland pony (n = 10) and Iceland pony mares (n = 11). Concentrations of oestrogens, 20alpha-hydroxy- and 20-oxopregnanes were measured using enzyme immunoassays. Breed differences concerning both levels (though significant only in case of oestrogens) and time course of measured steroids were observed. There was a highly significant time effect (p < 0.00001) and an interaction between time and breeds (p < 0.02) for all steroids measured, suggesting that the time effect differs for different breeds. Oestrogen concentrations showed a decrease towards parturition, whereas in 20alpha-hydroxy- and 20-oxopregnane levels a pronounced increase was found 2 and I months, respectively, before parturition. A breed effect was only significant (p = 0.001) when comparing oestrogen concentrations and was mainly due to Iceland ponies, which had the lowest concentrations especially during the last 2 months of pregnancy. An almost significant (p = 0.06) breed effect was found for 20-oxopregnanes. In Iceland mares an additional increase in faecal pregnane content was already observed earlier, reaching maximum levels before the 60th day ante-partum (a.p.), followed by a decrease until the 30th day a.p. The ratio of 20-oxopregnanes to oestrogens in the samples was significantly higher (p < 0.006) in Iceland ponies in comparison with any other breed throughout all months before parturition. The breed differences observed in the amounts of oestrogens and/or progestagens present during late pregnancy may demonstrate micro-evolutionary changes in the endocrine system of a species.

Animals↗
PubMed1995

Timing of seasonal breeding in birds, with particular reference to New Zealand birds.

A model to explain the timing of seasonal breeding in birds is presented. It is assumed that, despite the wide range in egg-laying seasons, there are common physiological mechanisms which underlie seasonality in birds and that most, if not all, birds are photoperiodic. Birds are considered to possess an internal rhythm of reproduction which is synchronized with seasonal changes in the environment by external factors, particularly the annual cycle of daylength. The rhythm consists, at least in part, of regular changes in the photoperiodic response between states of photosensitivity and photorefractoriness. Avian breeding seasons effectively start in autumn when birds become photosensitive, regardless of when egg-laying occurs. The timing of breeding is then influenced by the rate of increase of hypothalamic 'drive' and by the sensitivity of the hypothalamus and pituitary gland to inhibitory feedback from gonadal steroids. If sensitivity is high, gonadal growth will not occur until the threshold daylength for photostimulation is exceeded after the winter solstice. Egg-laying then starts in late winter, spring or summer. Alternatively, steroid feedback may be relatively low and gonadal growth may be sufficiently rapid once the birds become photosensitive that breeding occurs in late autumn or winter. The time of egg-laying in birds may also be strongly influenced by supplementary information, such as social cues, food availability, temperature and rainfall and, in some species, this information is more important than daylength in determining the timing of breeding. The review also includes the first summary of the breeding seasons of New Zealand birds. The pattern of egg-laying is exactly the same in native birds, in birds introduced to New Zealand and in other Southern hemisphere birds from similar latitudes, with a broad peak of egg-laying occurring from September to December. In addition, annual cycles of steroid hormone concentrations in the North Island brown kiwi, the yellow-eyed penguin and the kakapo are consistent with results from many studies on Northern hemisphere birds. This model for the timing of breeding in birds can be applied to New Zealand birds and it is concluded that the physiological control mechanisms for the timing of seasonal breeding in New Zealand birds are similar to those of other birds.

Animals↗
PubMed2003

The effect of dietary energy and protein levels on production in breeding female ostriches.

1. In a study spanning two breeding seasons, we assessed the effect of different dietary energy and protein levels on body mass, body condition, and egg production of female ostriches. 2. During the first breeding season, groups were given diets with energy concentrations of 8.5, 9.5 and 10.5 MJ/kg dry mass (DM) metabolisable energy (ME) and protein concentrations of 135, 150 and 165 g/kg. In the second breeding season, groups were given diets with ME of 7.5, 8.5 and 9.5 MJ/kg and protein contents of 105, 120 and 135 g/kg. 3. Body mass of birds on diets of 7.5 and 8.5 MJ/kg ME decreased significantly in the course of the breeding season compared with birds fed on diets with higher energy contents and body measurements decreased, suggesting a loss of body condition. 4. Females fed on diets containing only 7.5 MJ/kg ME produced significantly fewer eggs at significantly longer intervals, resulting in fewer chicks hatched. 5. There was no significant difference in egg mass, initial chick mass, chick survival to one month of age and body mass of chicks at one month. 6. Dietary protein concentrations had no effect on egg production, egg mass, hatchability, initial chick mass, chick survival or chick mass at one month old. 7. The female ostriches regained their original body mass during the 4-month rest period between breeding seasons, but significant differences in some parameters during the second breeding season suggest that they may not have fully recovered their body condition. 8. A dietary energy content of 7.5 MJ/kg proved to have an adverse effect on egg production by breeding female ostriches, and it may be concluded from this study that a diet containing 8.5 MJ ME/kg DM and 105 g/kg protein should be regarded as the minimum that can be used for breeding female ostriches without compromising egg production.

Animal Feed↗
PubMed2000

Towards a unified theory of cooperative breeding: the role of ecology and life history re-examined.

We present quantitative models that unify several adaptive hypotheses for the evolution of cooperative breeding in a single framework: the ecological constraints hypothesis, the life-history hypothesis and the benefits-of-philopatry hypothesis. Our goal is to explain interspecific variation in the occurrence of cooperative breeding in terms of interspecific variation in life-history traits and ecological conditions. We analyse two models, according to whether or not helpers can inherit their parents' territory. Major results are (i) territory inheritance always promotes cooperative breeding; (ii) if territories are not inherited, neither ecological constraints nor variation in life-history traits predict interspecific variation in cooperative breeding; and (iii) if territories are inherited, the mechanism of density regulation is crucial in determining which factors promote cooperative breeding. If density dependence acts on the probability to obtain a free territory or on the survival of dispersers, variation in ecological constraints cannot explain variation in cooperative breeding. Lower adult mortality favours helping, not because it reduces the availability of free territories, but because it enhances the direct benefits of helpers. If density dependence acts on fecundity, lower probability of obtaining a free territory and lower survival of dispersers promote cooperative breeding. In this case, lower adult mortality works against the evolution of helping. We suggest that the difference between birds and social insects in the covariance between cooperative breeding and life-history traits is due to different mechanisms of density regulation that operate in these taxa, and we explain how natural selection on habitat choice might have caused these different mechanisms to operate.

Animals↗
PubMed2002

Interspecific reciprocity explains mobbing behaviour of the breeding chaffinches, Fringilla coelebs.

When prey animals discover a predator close by, they mob it while uttering characteristic sounds that attract other prey individuals to the vicinity. Mobbing causes a predator to vacate its immediate foraging area, which gives an opportunity for prey individuals to continue their interrupted daily activity. Besides the increased benefits, mobbing behaviour also has its costs owing to injuries or death. The initiator of mobbing may be at increased risk of predation by attracting the predator's attention, especially if not joined by other neighbouring prey individuals. Communities of breeding birds have always been considered as temporal aggregations. Since an altruist could not prevent cheaters from exploiting its altruism in an anonymous community, this excluded any possibility of explaining mobbing behaviour in terms of reciprocal altruism. However, sedentary birds may have become acquainted since the previous non-breeding season. Migrant birds, forming anonymous communities at the beginning of the breeding season, may also develop closer social ties during the course of the breeding season. We tested whether a male chaffinch, a migrant bird, would initiate active harassment of a predator both at the beginning of the breeding season and a week later when it has become a member of a non-anonymous multi-species aggregation of sedentary birds. We expected that male chaffinches would be less likely to initiate a mob at the beginning of the breeding season when part of an anonymous multi-species aggregation of migratory birds. However, their mobbing activity should increase as the breeding season advances. Our results support these predictions. Cooperation among individuals belonging to different species in driving the predator away may be explained as interspecific reciprocity based on interspecific recognition and temporal stability of the breeding communities.

Aggression↗
PubMed2006

Inadvertent social information in breeding site selection of natal dispersing birds.

Several species use the number of young produced as public information (PI) to assess breeding site quality. PI is inaccessible for synchronously breeding birds because nests are empty by the time the young can collect this information. We investigate if location cues are the next best source of inadvertent social information (ISI) used by young prospectors during breeding site choice. We experimentally deployed ISI as decoys and song playbacks of breeding males in suitable and sub-optimal habitats during pre- and post-breeding periods, and monitored territory establishment during the subsequent breeding season for a social, bobolink (Dolichonyx oryzivorus), and a more solitary species, Nelson's sharp-tailed sparrow (Ammodramus nelsoni). The sparrows did not respond to treatments, but bobolinks responded strongly to post-breeding location cues, irrespective of habitat quality. The following year, 17/20 sub-optimal plots to which bobolink males were recruited were defended for at least two weeks, indicating that song heard the previous year could exert a "carry-over attraction" effect on conspecifics the following year. Sixteen recruited males were natal dispersers, as expected when animals have little opportunity to directly sample their natal habitat quality. We suggest that differences in breeding synchronicity may induce an equivalent clinal distribution of ISI use.

Animals↗
PubMed2004

Contributions of Portuguese cattle breeds to genetic diversity using marker-estimated kinships.

The quantitative assessment of genetic diversity within and between populations is important for decision-making in genetic conservation plans. In our study, we applied the livestock core set method to define the contribution of 15 cattle breeds, 11 of which are Portuguese indigenous cattle breeds, to genetic diversity. In livestock core set theory genetic diversity is defined as the maximum genetic variance that can be obtained in a random-mating population that is bred from the populations present in that core set. Two methods to estimate marker-estimated kinships to obtain the contributions to the core set were used in this study: the weighted log-linear model (WLM) and the weighted log-linear mixed model (WLMM). The breeds that contributed most to diversity in the core set were Holstein-Friesian followed by the Portuguese Mertolenga and Cachena for both WLM and WLMM methods. The ranking of relative contributions of cattle breeds was maintained when we considered only the Portuguese cattle breeds. Furthermore, we were able to identify the marginal contributions and respective losses of diversity for each of the 11 Portuguese cattle breeds when we considered a subset of populations that are not threatened of being lost (the Safe set composed of the four exotic breeds present in this study). When WLM was used losses in genetic diversity ranged from 2.68 to 0.65% while the loss in founder genome equivalents ranged from 37.37 to 8.43% for Mertolenga and Brava de Lide breeds respectively. When WLMM was used losses in genetic diversity and founder genome equivalents were less extreme than for the WLM method, ranging from 1.27 to 0.69 and 26.8 to 12.99 respectively.

Animals↗
PubMed2005

Administration of hCG 5 days after breeding and reproductive performance in nulliparous dairy goats.

The objective of this study was to investigate the effect of hCG administration 5 days after breeding on plasma progesterone (P4) concentration and reproductive performance of oestrous-induced nulliparous dairy goats. A total of 59 nulliparous goats (36 Alpine and 23 Saanen) received intravaginal sponges with 60 mg medroxyprogesterone acetate for 9 days plus 200 IU equine chorionic gonadotrophin (eCG) and 22.5 microg d-cloprostenol 24 h before sponge removal. After detection of oestrus (day of oestrus = day 0) and breeding, 49 females were randomly assigned, according to the breed, into two treatments (T1 and T2). In T1 (n = 25) and T2 (n = 24), animals received intramuscular injection of 1 ml of saline solution (control) or 250 IU hCG, respectively, 5 days after breeding. Plasma P4 concentration (ng/ml) was determined from blood sampled on days 0, 5, 7, 13, 17, 21, 28 and 45 after breeding. Animals were scanned by transrectal ultrasound (5 MHz probe) on days 35 and 70 after breeding for detection of pregnancy. Plasma P4 concentration did not differ (p > 0.05) between treatments in all days, but it was increased (p < 0.05) in Saanen than in Alpine goats from days 13 to 45. Pregnancy and parturition rates, litter size and gestation period were similar (p > 0.05) to treatments and breeds. Results of this study indicate that human chorionic gonadotrophin (hCG) administration 5 days after breeding did not significantly alter reproductive performance in dairy nulliparous goats and that plasma P4 differed between Saanen and Alpine goats.

Animals↗
PubMed1999

Effects of treadmill exercise on sweating in three breeds of goats.

OBJECTIVE: To compare the sweating responses of three breeds of goats to exercise at 30 degrees C. DESIGN: Factorial experiment with two goats of each of three breeds exercised for 60 min at 3 km/h and 30 degrees C on 6 days. PROCEDURE: Two mature females of the Anglo-Nubian, Saanen and Toggenburg breeds were used. Rectal temperature, respiration rate and sweating rate at three sites were recorded every 20 min during six replicates of exercise at 48 h intervals on a treadmill. RESULTS: Respiration rate varied with time and breed (P < 0.01) and increased from 20 +/- 2 breaths/min to 135, 195 and 260/min after 60 min exercise in Anglo-Nubian, Saanen and Tottenburg goats, respectively. Bread differences in rectal temperature were small but significant (P < 0.001), and mean values increased from 38.9 degrees C before exercise to 39.7 degrees C after 1 h exercise. The breed x sites interaction for sweating was significant (P < 0.01). On the rump breed differences in sweating rate were not significant. On the loin, Toggenburg goats started to sweat most rapidly and reached maximal values of 80.2 +/- 10.6 g/m2/h after 20 min and then decreased to 70.0 +/- 4.3 g/m2/h at 60 min. Sweating rate on the ear was highest in Toggenburg goats, followed by those of Saanen and Anglo-Nubian goats (P < 0.05), but the differences were small (7 g/m2/h); peak values of 67.3 to 76.1 g/m2/h were recorded after 20 min. CONCLUSION: Respiration and sweating rates increased significantly during exercise in all three breeds of goats, but breed differences were marked only for respiration rate. The goats sweated more on the rump than on the loin on ear, with peak values after 40 min of exercise.

Analysis of Variance↗
PubMed1985

Evidence that the onset of the breeding season in the ewe may be independent of decreasing plasma prolactin concentrations.

Ten ewes of each of two breeds, Dorset Horn (long breeding season) and Welsh Mountain (short breeding season), were given subcutaneous oestradiol-17 beta implants and then ovariectomized. Another 10 ewes of each breed were left intact. On 3 May 1982, all the ewes were housed in an artificial photoperiod of 16L:8D. After 4 weeks, half of the ewes of each breed and physiological state were abruptly exposed to a short-day (8L:16D) photoperiod while the others remained in long days (16L:8D). The time of onset of the breeding season was significantly (P less than 0.05) advanced in ewes switched to short days (12 August +/- 10 days) compared to those maintained in long days (4 September +/- 14 days). Dorset Horn ewes began to cycle (20 July +/- 7 days) significantly (P less than 0.001) earlier than Welsh Mountain ewes (19 September +/- 6 days). Disparities in the time of onset of cyclic activity in ewes of different breeds and daylength groups were echoed in disparities in the time at which plasma LH and FSH concentrations rose in oestrogen-implanted, ovariectomized ewes of the same light treatment group. Prolactin concentrations showed an immediate decrease in ewes switched to short days, but remained elevated in long-day ewes. Since the breeding season started in the presence of high prolactin concentrations in long-day ewes, it seems unlikely that prolactin is an important factor determining the timing of the onset of cyclic activity.

Animals↗
PubMed2005

Unequal contribution of sexes in the origin of dog breeds.

Dogs (Canis familiaris) were domesticated from the gray wolf (Canis lupus) at least 14,000 years ago, and there is evidence of dogs with phenotypes similar to those in modern breeds 4000 years ago. However, recent genetic analyses have suggested that modern dog breeds have a much more recent origin, probably <200 years ago. To study the origin of contemporaneous breeds we combined the analysis of paternally inherited Y chromosome markers with maternally inherited mitochondrial DNA and biparentally inherited autosomal microsatellite markers in both domestic dogs and their wild ancestor, the gray wolf. Our results show a sex bias in the origin of breeds, with fewer males than females contributing genetically, which clearly differs from the breeding patterns in wild gray wolf populations where both sexes have similar contributions. Furthermore, a comparison of mitochondrial DNA and Y chromosome diversity in dog groups recognized by the World Canine Organization, as well as in groups defined by the breeds' genetic composition, shows that paternal lineages are more differentiated among groups than maternal lineages. This demonstrates a lower exchange of males than of females between breeds belonging to different groups, which illustrates how breed founders may have been chosen.

Animals↗
PubMed1990

Efficiency of weight gain of serial slaughtered bulls of a five-breed diallel.

Weight and feed consumption of 197 bulls were recorded monthly in a serial slaughter experiment continuing over a period of 24 mo. The bulls were produced in a modified five-breed diallel of the Angus, Brahman, Hereford, Holstein and Jersey breeds. Our objective was to estimate efficiency of feed conversion for weight gain for each breed and cross. The model included average weight gain per day (ADG) as a dependent variable; independent variables included breed-type, season, month within season, average feed intake per day (ADI), initial weight, weight to the .75 power, breed x ADI and season x ADI effects. The sum of the partial regression coefficients of ADG on ADI and on breed x ADI adjusted for season, month within season, initial weight, weight to the .75 power and season x ADI was interpreted to be an estimate of intrinsic or net efficiency of ADG. There were no significant differences among the various breed-types in intrinsic efficiency of ADG. Average heterosis for intrinsic efficiency of feed conversion was not significant. None of the contrasts among breed-types was significant for intrinsic efficiency of ADG (British vs dairy, 1.1 +/- 12.3 g/d; Brahman-dairy crosses vs British-dairy crosses, 32.7 +/- 12.9 g/d; British-Brahman crosses vs British-dairy crosses, 13.9 +/- 12.4 g/d; British-Brahman crosses vs straightbred British 3.2 +/- 14.8 g/d).

Animals↗
PubMed1990

Breed effects on crossbred cow-calf performance.

Effects of seven breeds of cow's sire and 12 breeds of cow's maternal grandsire on preweaning performance of crossbred cows and their calves were examined in data from two experiments conducted at the Roman L. Hruska U.S. Mean Animal Research Center. Data included 1,836 records over three to five parities for 516 cows by 143 sires and by 307 maternal grandsires. The statistical model fitted effects of calf sex, parity, cow birth-breeding year or cow-calf birth year, the breed effects and their interactions. Deviations of breed of sire or equivalent grandsire effects on each trait from the mean for Hereford x Angus cows ranged from -1.6 to 5.5 kg (P less than .001) for calf birth weights, -15 to 1% (P less than .001) for calving difficulty, nonsignificant for preweaning calf mortality and -2 to 27 kg (P less than .001) for calf weaning weight. Deviations were nonsignificant for conception rate and calves weaned per cow exposed to breeding, but -2 to 40 kg (P less than .001) for calf weight weaned per cow exposed for breeding, -7 to 78 kg (P less than .001) for cow weight and -20 to 2% (P less than .001) for body condition score. The advantages of Holstein and Brahman cross over Hereford x Angus cows of 23 and 13% in weight of calf weaned/cow-breeding exposure must be compared with the expected greater feed requirements from 7 or 8% heavier cows and at least 50% higher milk production, which emphasizes the need to include input measures and costs in breed evaluation schemes.

Animals↗
PubMed1992

Evaluation of mating systems involving five breeds for integrated beef production systems: III. Integrated system.

Angus (A), Charolais (C), Hereford (H), Limousin (L), and Simmental (S) breeds were included in deterministic computer models simulating integrated cow-calf-feedlot production systems. Three mating systems were used: pure-breeding and two-and three-breed rotational crossbreeding. Breed information was taken from the literature. Herd sizes were unrestricted; however, 100 heifers were saved as replacements. Cows were removed for reproductive failure, age (greater than 10.5 yr), or death. Calves produced in the cow-calf segment were fed in a custom feedlot to four slaughter end points: 440 d, 457 d, 288-kg carcass weight, and low Choice. All animals were fed to requirements. Cull cows were slaughtered after weaning. Biological and economic efficiencies improved with crossbreeding; however, rankings of breed combinations depended on how efficiencies were measured (weight, lean, or value basis). Among purebreds, reproductive performance had a large influence on breed rankings at age and weight end points, whereas feedlot performance was important at the low Choice end point. Crossbred combinations involving British (A or H) and Continental (C or S) breeds were more efficient than other crossbred combinations at all end points. However, choosing specific breed combinations for integrated systems depends on slaughter end points, market end points (weight vs lean), and measures of efficiency (weight, lean, or value basis).

Animal Husbandry↗
PubMed1993

Effect of sire and dam breed on copper status of fat lambs.

To determine the effect of breed on copper status of crossbred (F1) lambs, a study was conducted using 187 crossbred wether lambs. Wether lambs were progeny of five ram breeds (Dorset, Finnsheep, Montadale, Romanov, and Texel) and two ewe breeds (Rambouillet and a composite breed [1/2 Columbia, 1/4 Suffolk, 1/4 Hampshire]). Diets were adjusted to decrease crude protein twice during the experimental period, with analyzed copper levels for the three diets of 5.2, 4.4, and 3.6 ppm. All means were adjusted to a constant carcass weight of 27.265 kg using a covariate analysis. Least squares means of the liver copper concentration for sire breeds ranged from 307 to 458 micrograms/g on a DM basis. Romanov- (307 micrograms/g) and Finnsheep-sired (327 micrograms/g) lambs had the lowest liver copper concentration, whereas Montadale- (359 micrograms/g) and Dorset-sired (360 micrograms/g) lambs were intermediate and Texel-sired (458 micrograms/g) lambs were significantly higher compared with other lamb breeds. Least squares means for total liver copper for the five ram breeds ranged from 69 to 101 mg. Finnsheep- (69 mg), Romanov- (72 mg), and Montadale-sired (80 mg) lambs were lowest, Dorset-sired (85 mg) lambs were intermediate, and Texel-sired (101 mg) lambs were higher (P < .02) compared with other lamb breeds for total liver copper. Least squares means for serum copper ranged from .86 to 1.05 ppm. Levels of serum copper were similar for Montadale- (.86 ppm), Finnsheep- (.90 ppm), Texel- (.93 ppm), and Dorset-sired (.94 ppm) lambs and higher (P < .02) for Romanov-sired (1.05 ppm) lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1993

Diallel cross of three Moroccan breeds of sheep: I. Lamb growth and carcass traits.

A diallel cross involving three Moroccan breeds of sheep (D'man, Beni Guil, and Sardi) was conducted for two successive years at the Gharb Experiment Station in Morocco. Significant effects associated with breed of sire and breed of dam for live and carcass weights are consistent with differences in mature body size of the three breeds involved. Carcasses of lambs by Sardi sires or out of Sardi dams were the heaviest and those by D'man sires or out of D'man dams were the lightest. Lambs by D'man sires reached the prescribed stage of maturity for slaughter at a younger age than did lambs of Beni Guil sires, and lambs out of Beni Guil dams were younger at slaughter than lambs out of Sardi dams. Because of its genetic potential for high growth rate and carcass weight, the Sardi breed could be used in breeding programs to enhance meat production from sheep in Morocco. With the large and desirable maternal effects expressed by the Beni Guil breed on growth traits and carcass weight per 100 d of age, it could also be used in Morocco as a breed of dam.

Adipose Tissue↗
PubMed1994

Productivity through weaning of nine breeds of cattle under varying feed availabilities: I. Initial evaluation.

The effect of varying dry matter availability on the conversion of dry matter resources to weight of calf at weaning was evaluated for nine breeds of cattle; Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Red Poll, Pinzgauer, and Simmental were recorded for 5 yr. Within each breed, four cows were assigned to each of four feeding levels of dry matter intake: 58, 76, 93, or 111 g of DM/wt75. Cows remained on their assigned diet regimen throughout the study. Individual cow consumption, daily feed allowance adjusted for refusal, was recorded weekly. Production information included birth and weaning weight of the progeny, calving rate, and cow weights and condition scores. Cows were exposed to bulls of the same breed for 90 d. Reasons for cow replacement included failure to conceive in two successive years, injury, Caesarean section, chronic illness, and death. Response to dry matter intake (DMI) was curvilinear and differed among breeds (P < .10) for calving rate, calf survival, and weight of calf weaned per cow exposed. Significant differences occurred among the breeds for the linear response to DMI for cow weight and condition score. The response to DMI was curvilinear for birth weight (P < .10), but the response did not differ among breeds (P > .20). Red Poll exhibited more effective conversion at DMI less than 4,000 kg/yr, but breeds with greater genetic potential for growth and(or) milk production (Gelbvieh, Charolais, Braunvieh, Simmental, Pinzgauer, and Limousin) were more efficient at DMI greater than 6,000 kg/yr. Ranking for biological production efficiency (weight of calf weaned-cow exposed-1.kg DMI of cow-1) through weaning among breeds of cattle varied with dry matter intake.

Analysis of Variance↗