Agonistic interactions in developed and undeveloped breeds of chickens

1. Agonistic interactions were observed over a 24‐week period in Rhode Island Red and in Nigerian local fowl aged 32 weeks or 12 weeks at the start of the experiments.

2. Agonistic interactions were both more numerous and more severe (fights and peck avoidances) in groups of the local breed than in those of Rhode Island Reds.

3. The outcome of severe interactions favoured local males and Rhode Island females in the first experiment and Rhode Island males in the second.

4. Small body and comb size might account for the relatively high number of agonistic interactions and the submissiveness of local females and young males while physical strength or some other breed characteristic might account for the high number of agonistic interactions of local males as well as their dominance in breed encounters.     

Lack of straw during finishing affects individual and social lamb behavior

The aim of this study was to analyze the effect of straw bedding on individual and social behavior in lambs. Four groups of 6 lambs of the Rasa Aragonesa breed (n = 24; 17.2 ± 0.2 kg live weight and approximately 60 days old) were formed and fattened for 28 days, in an experimental design that included 2 treatments and 2 replicates. One treatment was given cereal straw either to eat or to lie on, whereas the other treatment had no straw. All groups were housed in 5.6 m² feedlot pens (ad libitum commercial concentrate and water). The lambs in each pen were recorded using a digital video camera (08:00-20:00 hours) for 28 days to measure lying, standing, walking, feeding, and drinking behavior as well as the use of space (scan sampling every 10 minutes). Stereotypies, social interactions, and productive performance parameters were observed by continuous sampling on days 1, 7, 14, 21, and 28 of fattening. There were no significant differences in terms of productive performance. In general, the frequency of standing, walking, and eating concentrate was higher in lambs without straw (P ≤ 0.001). As expected, lambs spent more time standing in the straw box when this substrate was available (P ≤ 0.001). Aggressive interactions decreased after 2 weeks in both treatments, but just lambs without straw kept low levels until the end of the trial (P ≤ 0.05). Affiliative interactions increased in both groups throughout the experiment, indicating greater group cohesion. Stereotypic behaviors were more frequent in lambs with no straw on all observation days (P ≤ 0.05). The absence of cereal straw was a source of stress for the lambs, which affected their behavior during fattening. Providing straw can be a practical way to increase environmental enrichment aimed at improving welfare.     

A note on the effect of number (single or twin) and sex of contemporary siblings on male-like play behavior of lambs (Ovis aries)

This study evaluates the effect of the number and sex of contemporary siblings on male-like play behavior of Suffolk lambs (Ovis aries). Fourteen males and 14 females, all single born, plus 26 ram lambs born co-twin to another male (n = 14) or female (n = 12) as well as 26 ewe lambs born co-twin to another male (n = 12) or female (n = 14) were observed daily for 7 weeks from 1 week of age. Two observers sitting outside a sand-bedded pen (10 × 5 m) recorded received and performed behavior (butts, nudging, attempts to mount, and mounts) by the lambs in the pen from 08:00 to 09:00 and 16:00 to 17:00 hours. Animals were in the pen only during the observation periods; the rest of the day they remained with their mothers in individual pens. Male-like play behavior patterns were displayed by both male and female lambs. Males were more active (P < 0.05) than females. Butting was the most frequent activity and performed mostly by ram lambs, recipients were generally males, and most resulted in reciprocal simultaneous encounters (sparring). Single males performed most of the nudging activity, which was the least frequent of the observed behaviors. Males with twin brothers mounted significantly (P < 0.05) more than males with twin sisters, and females with twin sisters performed the lowest amount of gutting and nudging. Lower (P < 0.05) levels of activity were found during the first 2 weeks. Overall, it was concluded that male lambs performed and received more male-like play behaviors than female lambs and the influence of sex of contemporary sibling was restricted to some behaviors: butting and nudging in females and mounting in males.     

南非克鲁格斯多普禁猎区珠鸡的社群组织

1982年3月至1984年2月,在南非豪登省的克鲁格斯多普禁猎区(Krugersdorp Game Reserve),通过翼标观察对珠鸡(Numida meleagris)的社群组织进行了研究.珠鸡必须以社群的方式才能在野外存活,而集群(7-10只珠鸡)并非随机组成.地位最高的雄鸟(雄鸟A)是群体日常活动的核心,例如决定觅食方向等.地位较高的雄鸟(雄鸟A和B)密切协作以驱赶闯入者.在繁殖期,繁殖雌鸟与高地位雄鸟的结合更为紧密.尽管雄鸟中存在明显的等级差异,但群内争斗频率很低,这些争斗只是在维系群体稳定时才发生.雌性成鸟始终位于优势雄鸟和亚成体之间,以免受天敌伤害.但优势雄鸟与其配偶暂时离开群体进行繁殖时,次优势雄鸟(雄鸟B)成为集群中心,其余个体聚集在其周围以保持集群的稳定.大多数成鸟都协助抚育优势雄鸟的雏鸟.珠鸡的集群具有监视天敌的作用,以保障其在地表植被有限的环境中觅食并在冬季最大限度地获得食物.     

Variation in food selection among lambs: effects of basal diet and foods offered in a meal.

In studies of behavior and nutrition, we typically determine nutritional needs and formulate diets for the average member of the herd, not for specific individuals within a herd. Nevertheless, variation among individuals could affect productivity of the group if the diet diverges too much from what individuals at the extremes prefer to eat. Thus, it is important to determine the degree to which individuals within a group vary in their food preferences when offered alternatives. Our first objective was to determine the degree to which lambs differed in preference for foods high in energy (barley) or protein (alfalfa) (Exp. 1). When we offered lambs barley and alfalfa for ad libitum consumption for 25 d, individuals varied in the amounts of barley (range: 221 to 991 g/d) and alfalfa (range: 51 to 558 g/d) they consumed (P < .0001). At one extreme, individuals preferred a diet of 6% alfalfa and 94% barley; at the other extreme, individuals preferred a diet of 70% alfalfa and 30% barley. Our second objective was to determine whether lambs from Exp. 1 compensated, when fed a basal diet that was lower in alfalfa than they preferred, by ingesting foods higher in alfalfa when offered a meal (Exp. 2). Lambs were ranked according to the percentage of alfalfa (range from 6 to 70%) and barley (range from 94 to 30%) they ate during Exp. 1 and then assigned alternately to two treatments: 1) basal diet with similar proportions of alfalfa and barley consumed ad libitum (preferred diet) or 2) basal diet with 10% less alfalfa than consumed ad libitum (low-alfalfa diet). We then conducted three trials in which lambs fed the different basal diets were offered a meal for 15 min/d for 2 d of two foods that differed in barley and alfalfa. During Trial 1, when we offered barley and alfalfa, lambs in both groups preferred barley (138 g) to alfalfa (46 g) (P < .05). During Trial 2, when the test foods (barley and alfalfa) were diluted with grape pomace (20%), lambs fed the preferred basal diet ate more barley (116 vs 64 g) and less alfalfa (48 vs 87 g) than lambs fed the low-alfalfa basal diet (P < .05). During Trial 3, when we offered a food high in barley (80% barley and 20% pomace) and a food high in alfalfa (70% alfalfa, 14% cornstarch, and 16% pomace), lambs fed the preferred basal diet ate more of the high-barley food (124 vs 73 g) and less of the high-alfalfa food (45 vs 98 g) than lambs fed the low-alfalfa basal diet (P < .05). Collectively, these results illustrate that lambs varied greatly in their preferences for foods that differ in energy (barley) and protein (alfalfa), and that when their preferred basal diet was altered, lambs compensated by ingesting food that complemented their basal diet during a daily meal. The addition of grape pomace in Trials 2 and 3 reduced the protein content of the high-barley and high-alfalfa foods such that the high-barley food was only marginally adequate to meet needs compared with the high-alfalfa food. Lambs fed the low-alfalfa basal diet compensated by eating more of the high-alfalfa food than lambs fed the preferred basal diet.     

Effect of birth weight,gender and litter characteristics on summer mortality in lambs of Norwegian breeds

Abstract

This study describes how birth weight, gender, litter size, and age of dam affect lamb mortality during the summer period, using data on lambs of the breeds Spælsau (N ≈ 110 000) and Norwegian White Sheep (N ≈ 450 000) during 1994 to 2005. A general mixed linear model was used for the analysis. Birth weight affected summer mortality non-proportionally: an increase in weight from very small towards the breed mean strongly deflated mortality risk; weigh increase above breed means had little effect. Male lambs had a higher mortality than females, and lambs born by 12-months-old dams were in greater risk than those having older dams. Increasing litter size resulted in increased mortality. The results are discussed and recommendations for future research, with focus on breeding and genotype by environment interaction effects are made.     

Breed and trait preferences of Sheko cattle keepers in southwestern Ethiopia

Like their smallholder subsistence counterparts in developing countries, breed and trait preferences of Sheko cattle keepers have broad perspectives. Our study has documented breed and trait preferences of Sheko cattle keepers in southwestern Ethiopia—the natural breeding tract of Sheko cattle. Our results showed that due to their multifunctionality, cattle are the most preferred livestock species. Overall, farmers showed slightly more preference to local Zebus over Sheko breed. This is due to voracious feeding behavior of Sheko cattle, which make them less preferable in the face of worsening feed shortage, and due to aggressive temperament of Sheko cattle. This is despite Sheko's outperforming potential over local Zebus in their milk production, draft power, and hardiness. At trait level, overall milk production was consistently reported as the most preferred trait followed by fertility and traction. This trait preference rank has matched with the reported frequency count ranks for Sheko cattle use. However, breed preference rank has not matched with reported trait preference ranks because Sheko excels local Zebus in all the three most preferred traits, but it was ranked second. Therefore, to minimize these conflicting interests, breed management plans for Sheko cattle should target on strategies that help to solve feed shortage problem and to improve feeding practices, and on selection of less aggressive Sheko cattle. Therefore, these strategies should be considered in line with Sheko cattle conservation and genetic improvement programs.     

Estimation of sheep carcass traits by ultrasound technology

Real-time ultrasound technology offers the possibility of estimating carcass characteristics in live animals and represents a potential method for selection of breeding stocks. A total of 745 live lambs born during 2001–2003 into two flocks was used to estimate rib muscle and fat depth by ultrasound. Lambs came from 559 ewes and 97 rams of a fat-tailed breed, known as the ‘Barbarine’ in North Africa. Ultrasound measurements of external fat thickness (UFD) and muscle (UMD), taken at the 12–13th rib and palpation of body conditions (loin and tail scores) were made for 150 days until lambs 520 days old of lamb ages. Main results showed that UMD and UFD had the same trend as live weights from 150 to 240 days old. They decreased from 150 to 200 days old, and then increased. The same trend was seen for loin and tail scores. Average differences in live weights between male and female lambs were 1, 3 and 6 kg at 30, 90 and 120 days old, respectively. The highest muscle depth for males was reached at day 180 and the lowest fat depth was recorded between 180 and 200 days. Average loin scores became greater for males than females from 240 days of age. Male lambs had greater tail scores at all ages, from 150 to 520 days old. Differences became greater for ages more than 180 days, showing that males have a tendency to store more fat in their tails than females. Phenotypic correlation was 0.70 between muscle depth and loin scores, indicating that, at 180 days old, the Barbarine breed has more muscle and less fat. The optimum slaughter age was defined between 180 and 200 days old, producing carcasses with more muscle and less fat. Regression equations estimating carcass traits (UMD, UFD) at 180 and 240 days old were computed.     

A comparative study of clinical manifestations,haematological and serological responses after experimental infection with Anaplasma phagocytophilum in two Norwegian sheep breeds

Background

It has been questioned if the old native Norwegian sheep breed, Old Norse Sheep (also called Norwegian Feral Sheep), normally distributed on coastal areas where ticks are abundant, is more protected against tick-borne infections than other Norwegian breeds due to a continuously high selection pressure on pasture. The aim of the present study was to test this hypothesis in an experimental infection study.

Methods

Five-months-old lambs of two Norwegian sheep breeds, Norwegian White (NW) sheep and Old Norse (ON) sheep, were experimentally infected with a 16S rRNA genetic variant of Anaplasma phagocytophilum (similar to GenBank accession number {"type":"entrez-nucleotide","attrs":{"text":"M73220","term_id":"148293"}}M73220). The experiment was repeated for two subsequent years, 2008 and 2009, with the use of 16 lambs of each breed annually. Ten lambs of each breed were inoculated intravenously each year with 0.4 ml A. phagocytophilum-infected blood containing approximately 0.5 × 10⁶ infected neutrophils/ml. Six lambs of each breed were used as uninfected controls. Half of the primary inoculated lambs in each breed were re-challenged with the same infectious dose at nine (2008) and twelve (2009) weeks after the first challenge. The clinical, haematological and serological responses to A. phagocytophilum infection were compared in the two sheep breeds.

Results

The present study indicates a difference in fever response and infection rate between breeds of Norwegian sheep after experimental infection with A. phagocytophilum.

Conclusion

Although clinical response seems to be less in ON-lambs compared to NW-lambs, further studies including more animals are needed to evaluate if the ON-breed is more protected against tick-borne infections than other Norwegian breeds.     

Birth to weaning kid traits from a complete diallel of Boer, Kiko, and Spanish meat goat breeds semi-intensively managed on humid subtropical pasture

Boer, Kiko, and Spanish meat goats were semi-intensively managed in a complete 3-breed diallel mating scheme to evaluate genetic effects on preweaning kid performance. Over a 6-yr period, 1,547 kids were born in March and May with 1,173 kids raised by their dams to weaning at 3 mo of age. March-born kids were lighter (P < 0.01) at birth, but had greater (P < 0.01) preweaning ADG and survival rates and heavier (P < 0.01) weaning weights than May-born kids. For birth weight, the direct Boer effect was positive (P < 0.01) and direct effects were negative (P < 0.01) for Kiko and Spanish. The direct Kiko effect for preweaning ADG was positive (P < 0.05), whereas other direct breed effects for ADG and all direct effects for weaning weight did not differ from 0 (P > 0.10). Maternal Boer effects were negative (P < 0.01) for birth weight and weaning weight, whereas maternal Kiko effects were significantly (P < 0.05) positive for preweaning ADG and weaning weight. Maternal Spanish effect was positive (P < 0.05) for birth weight, but did not differ from 0 (P > 0.5) for preweaning ADG or weaning weight. Heterosis for birth weight was exhibited (P < 0.01) for each pair of breed crosses, but only between Boer and Kiko for ADG and weaning weight. Kiko and Spanish dams had greater (P < 0.01) preweaning kid survival rates than Boer dams, but the former 2 did not differ (P = 0.72). Significant genetic variation was observed between meat goat breeds for kid performance to weaning. Maternal breed effects were more influential than direct breed effects. Boer goats were not superior to Kiko or Spanish for preweaning kid performance when semi-intensively managed on humid, subtropical pasture. Kiko should be a preferred breed and to a lesser extent Spanish for enhancing birth to weaning kid performance. Findings of this study emphasize the importance of proper doe breed selection in achieving desired kid performance to weaning in meat goats.     

Sexual performance of rams as determined by maturation and sexual experience

The purpose of this study was to compare the sexual performance of rams that differed in age (maturation) and sexual experience. Twenty-four ram lambs (8 mo of age) and 21 rams (20 mo of age) were individually exposed to four females in hormonally induced estrus for 30 min on five occasions, 7 d apart. Half (12) the ram lambs and nine of the yearlings were sexually naive at the start of testing (had been denied access to females since weaning); the remaining males were sexually experienced. The sexual performance of the virgin rams was poorer during the initial exposure to females than in subsequent tests, whereas the sexual behavior of the sexually experienced males did not change over the days of testing. Sexually naive ram lambs and rams exhibited an improvement in sexual performance between Tests 1 and 2; during Test 3 to 5 the sexual performance (ejaculations per test) of sexually naive and experienced rams was similar. The only effects of age (maturation) on sexual performance during the last three test days were a higher frequency of mounts without ejaculation plus mount attempts (P less than .03) and a greater number of mount interactions per ejaculation (P less than .02) by ram lambs. In conclusion, one or two relatively brief exposures to estrous females can bring the sexual performance of virgin rams up to levels comparable to that of experienced males. Also, ram lambs in good condition exhibit acceptable levels of sexual performance.     

Investigating equine ingestive, maternal, and sexual behavior in the field and in the laboratory.

Some of the techniques that may be used to study social, reproductive, and ingestive behavior in horses are described in this paper. One of the aspects of equine social behavior is the dominance hierarchy or patterns of agonistic behavior. Paired or group feeding from a single food source may be used to determine dominance hierarchies quickly. Focal animal studies of undisturbed groups of horses may also be used; this method takes longer, but may reveal affiliative as well as agonistic relationships among the horses. Reproductive behavior includes flehmen, the functional significance of which can be determined using combinations of field observations of harem groups and laboratory studies of stallions exposed to female urine or feces in the absence of the donor mare. Ingestive behavior may include food, salt, or water intake. Direct and indirect measurements of intake can be made and used to answer questions regarding the ability of horses to control their energy intake when the diet is diluted, the effect of feral equids on the ecology of an area, and the abilities of horses to compensate for dehydration and hypovolemia.     

The effect of sex and genotype on growth performance,feed efficiency,and carcass traits of local sheep group Pantaneiro and Texel or Santa Inês crossbred finished on feedlot

This study aimed to assess and compare the growth performance, feed efficiency, and carcass traits of Pantaneiro sheep and their Texel and Santa Inês crossbreds. Ninety-six lambs, fifty-one males, and forty-five females, with a mean weaning weight of 15.21?±?1.25 kg and 78?±?13 days of age, were slaughtered at a 32-kg body weight. The results showed better production efficiency from males compared with females. Texel-crossed lambs had a better growth performance than the other genotypes. The Texel?×?Pantaneiro lambs were more efficient with a better feedlot performance, higher ribeye muscle area, and better carcass characteristics with an adequate amount of fat cover. Pantaneiro lambs and their crosses with meat breeds could be useful in meat production systems under Savanna environmental conditions.     

The establishment and persistence of food preferences in lambs exposed to selected foods

Our study determined whether lambs' food preferences developed as a result of exposure to specific foods early in life and whether the presence of the mother affected the development of dietary preferences. In the first experiment, lambs were fed wheat (W) and mountain mahogany (MM) (Cercocarpus montanus) from 50 to 110 d of age. After exposure to W and MM, lambs preferred (P less than .05) W when offered with barley (B) but did not prefer (P greater than .05) MM when offered with serviceberry (SB) (Amelanchier alnifolia), probably because lambs were reluctant to eat mountain mahogany during exposure. Persistence was determined by dividing lambs exposed to W or MM into four groups: 1) continued exposure to W (MM); 2) exposure to B (SB); 3) no further exposure; and 4) exposure to W + B (MM +SB). Preferences for wheat persisted (P less than .05) regardless of the second exposure. In the second experiment, lambs were exposed to W (MM) either alone or with their mothers. Persistence was determined after 21 d of exposure to B (SB). Lambs preferred (P less than .05) W and MM whether they were exposed alone or with their mothers. However, preferences persisted longer in lambs exposed with their mothers. Finally, lambs exposed to either SB or MM with their mothers were later allowed to choose between SB or MM. Lambs strongly preferred (P less than .05) the shrub to which they were exposed early in life.     

Influence of management system on litter size, lamb growth, and carcass characteristics in sheep.

Three management systems (winter, spring, and late summer) distinguished by season of lambing and management practices were compared for litter size born and weaned and growth and carcass characteristics of lambs. Three sire breeds (Cheviot, Rambouillet, and Suffolk) and three dam breeds (Florida Native, Native-X, and Synthetic-X) were used in 698 matings over a 3-yr period. System affected (P < .01) litter size born. Spring lambing yielded more lambs (1.62) than winter (1.49) and late summer (1.12). The winter-born lambs were lighter but fatter (P < .05), and spring-born lambs were leaner with higher leg conformation and carcass quality scores. The late summer-born lambs were not different from spring-born lambs. Wethers had higher (P < .01) weights off test than ewe lambs (43.9 vs 42 kg) but had lower (P < .01) leg conformation scores, percentage kidney and pelvic fat, yield grade, and dressing percentages. Dam breed effects were significant (P < .05) for average preweaning daily gains with 249+/-5, 201+/-9, and 191+/-9 g for progeny of Native-X, Florida Native, and Synthetic-X, respectively. Single-born lambs had higher daily gains (P < .05) than twins in a preweaning period in all management systems and higher postweaning and lifetime daily gains for winter and spring management systems.     

Preference status does not indicate intrinsic quality differences in Drosophila pseudoobscura

The good genes hypothesis states that choosers prefer individuals of high intrinsic quality to individuals of lower intrinsic quality. Variation in longevity is thought to reflect, in part, intrinsic quality differences of individuals in addition to the costs of mating and reproduction. Here we report longevity variation of Drosophila pseudoobscura, a species in which previous experiments have demonstrated that individual mate preferences (pre-touching mate assessments) of females and males are associated with enhanced numbers of eclosed (adult) offspring and higher egg-to-adult survival (offspring viability). Using mate assessment arenas and protocols similar to those in a previous experiment that demonstrated fitness benefits to breeders and their offspring of mating with individuals they preferred, we tested the following predictions: (i) preferred discriminatees live longer than non-preferred discriminatees; (ii) males live longer than females; and (iii) virgins live longer than mated individuals. The experiment yielded 938 individuals for longevity analysis. Sex and mating status affected longevity: males lived longer than females, virgin females lived longer than mated females, but there were no differences in longevity for mated and virgin males. Non-preferred discriminatees of both sexes survived as long as preferred discriminatees, a result inconsistent with the prediction of the good genes hypothesis for mate preferences. To our knowledge, this is the first demonstration of the cost of reproduction for females in D. pseudoobscura and of longevity variation of preferred and non-preferred discriminatees.     

A mail survey of factors affecting performance in 627 selected sheep flocks in south-eastern Norway

Abstract

Factors influencing rate of barren ewes, number of lambs born per pregnant ewe, and autumn live weight of the lambs were studied in 627 Norwegian sheep flocks based on herd level data from the Norwegian Sheep Recording System and a mailed questionnaire to the sheep farmers. The following factors were significantly associated (P<0.05) with rate of barren ewes: breed, herd average lambing date, type of production/age of farmer, routines for treatments for parasites, and housing type. Number of lambs born per pregnant ewe was significantly associated with rate of barren ewes, herd average lambing date, breed, percentage grass silage of total roughage, and no separation of gimmers during the housing period. Corrected autumn live weight of the lambs was significantly associated with breed, flock size, lambs born per pregnant ewe, no separation of gimmers during the housing period, and type of summer pasture.     

Epidemiological observations and heterosis analysis of gastrointestinal nematode parasitism in Suffolk, Gulf Coast Native, and crossbred lambs.

A crossbreeding program was conducted to evaluate the resistant status to gastrointestinal nematode parasite infection in crossbred (F1) lambs and their Suffolk and Gulf Coast Native (Native) breed counterparts. A total of 253 lambs were included in the study over 2 years. Fecal egg count (FEC) and blood packed cell volume (PCV) of 18-20 monitor lambs of each breed group in each year were collected every other week from birth to 24-30 weeks of age. The FEC and PCV of all lambs were determined at weaning (11-12 weeks of age) and at three subsequent times when anthelmintic treatment was administered. Nematode counts of wether lambs were obtained at 30 weeks of age in the first year. The epidemiological patterns of FEC and PCV of each breed group were similar in both years. The Suffolk group consistently showed the highest FEC and the lowest PCV. Conversely, the Native group had the lowest FEC and highest PCV. For the most part, all parameters for the F1 group fell intermediate to the Native and Suffolk groups. Nematode count followed the same pattern. Heterosis analysis showed that FEC, PCV, nematode count and weight gain of the F1 group favored the Native group. These results suggested that crossbreeding Suffolk to Native sheep may be a suitable way to produce lambs with improved resistance to gastrointestinal nematode infection, but production may be compromised.     

Stable fighting strategies to maintain social ranks in captive male Alpine musk deer (Moschus sifanicus)

This study was conducted at the Xinglongshan Musk Deer Farm of China from July to September 2008. Results showed that captive male musk deer exhibit aggressive dominance behavior, by which a stable social ranking is established. Generally, there were three types of aggression in agonistic interactions among males: attacking, displacing and threatening. Threatening was more frequently observed than displacing and attacking. When in conflict with other deer, high‐rank males exhibited significantly more attacking than displacing and threatening. Moreover, no attacking occurred in low‐rank and middle‐rank males, but these individuals initiated significantly more threatening displays than high‐rank individuals. Among musk deer groups with different social ranks, there were no significant differences between threats received by middle‐rank and low‐rank groups, but attacks directed to high‐rank males was significantly lower than displacing and threatening behaviors. On the basis of these results, it is suggested that when a captive male musk deer population is assembled, individuals should be diversified in fighting ability and level of aggression. In particular, deer with higher aggression should not be enclosed with deer with similar tendencies, but should be enclosed with individuals with lower fighting levels. This should maintain stable social structures within captive musk deer groups and improve the overall welfare of captive musk deer.     

Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: I. Ewe productivity and crossbred lamb survival and preweaning growth

A 3-yr study was conducted to comprehensively evaluate columbia, suffolk, usmarc-composite (composite), and texel breeds as terminal sires in an extensive rangeland production system. The objective was to estimate breed-of-ram effects on ewe fertility, prolificacy, and dystocia, and sire breed effects on lamb survival and growth until weaning at approximately 132 d of age. Data were from 22 columbia, 22 composite, 21 suffolk, and 17 texel rams with 957 exposures to 574 adult rambouillet ewes (3- to 7-yr-old at lambing), 908 lambings, and 1,834 lambs. Ram breed did not affect ewe fertility (mean = 94.9%; p = 0.73), total number born per ewe lambing (mean = 2.02 lambs; p = 0.20), number born alive per ewe lambing (mean = 1.90 lambs; p = 0.24), or number weaned per ewe lambing (mean = 1.45 lambs, p = 0.94). Dystocia rates were different (p = 0.01) for ewes mated to columbia (12.2%), composite (13.5%), suffolk (25.7%), and texel rams (31.9%) during 1 yr of the study, but differences among ram breeds were not repeatable (p ≥ 0.38) during the other 2 yr. Suffolk-sired lambs were heavier (p ≥ 0.02) at birth (5.5 kg) and weaning (40.3 kg) than lambs sired by the other breeds, which did not differ (p ≥ 0.34) for birth weight (mean = 5.3 kg). Texel-sired lambs (37.4 kg) were lighter (p ≥ 0.02) at weaning than columbia- (38.8 kg) and composite-sired (38.4 kg) lambs, which did not differ (p = 0.40) for weaning weight. Sire breed effect approached significance (p = 0.06) for lamb survival to weaning; estimated survival probabilities were 0.87 (columbia), 0.89 (composite), 0.93 (suffolk), and 0.86 (texel) for lambs reared by their birth dam. Interaction between sire breeds and birth weight affected (p < 0.001) lamb survival and revealed that lightweight columbia- and suffolk-sired lambs had a greater risk of death than lightweight lambs sired by composite and texel rams, but risk of death did not increase substantially for heavyweight lambs from any of the breeds. When mated to adult rambouillet ewes in an extensive rangeland production system, the use of suffolk rams is warranted to improve preweaning growth of market lambs and is not predicted to affect ewe fertility, ewe prolificacy, dystocia, or lamb survival compared with the other sire breeds we tested.