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Biomedical subjects

J V Craig

Publications and source records attributed to J V Craig.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effects of feeding systems on social and feeding behavior and performance of finishing pigs.

Two experiments were conducted to study the effects of feeding systems on feeding behavior, aggression, social ranks and average daily gain (ADG) of pigs. In Exp. 1, feed was delivered during the day from 1100 to 1400 and at night from 2300 to 0200. One pen containing 10 barrows and 10 gilts was used. Correlation coefficients were calculated between pairs of traits. In Exp. 2, four feeding systems were tested using similar group composition as in Exp. 1. Two feeding systems were ad libitum, offering either dry or wet feed; the other two used time-restricted feeding from 0900 to 1100 and from 1600 to 1800, but with water supplied either ad libitum or time-restricted. Analyses of variance were used to test feeding system effects; correlation coefficients were calculated for pairs of traits. Results of Exp. 1 indicated that pigs displayed predominantly daytime activities. Frequency of aggressive acts were correlated significantly with feeding frequency (r = .48), time to first feeding (r = -.50) and ADG (r = .56). In Exp. 2, pigs on time-restricted feeding with ad libitum water had significantly depressed ADG and reduced feed intake. A possible association between time-restricted feeding and water intake is postulated. Feeding behavior, aggression and social rank were associated with ADG in time-restricted systems but not in ad libitum systems. There was a tendency in time-restricted-fed pigs for the more aggressive pigs to perform more feeding activities, to rank higher in the social order, and to gain faster.

Aggression↗
PubMed1987

Fear-related behavior of hens in cages: effects of rearing environment, age, and habituation.

At 18 weeks, pullets reared in floor pens and cages were placed in cages designed for laying hens. Tests were conducted for escape and avoidance behavior and for duration of tonic immobility at 23 and 40 weeks of age. Rearing environment effects were not detected for either measure. Paired comparisons did not reveal effects of age or habituation on duration of induced tonic immobility.

Animals↗
PubMed1987

Effects of body weight groupings on productivity, feather loss, and nervousness of caged hens.

Two experiments compared performance traits, feather loss, and nervousness of hens kept in contrasting homogeneous and heterogeneous body weight groupings. In addition, 15-day periods of daily uterine palpating vs nonpalpating for an egg in the uterus were compared for effects on egg production. Eighteen-wk-old pullets were weighed and characterized as light, medium, or heavy and housed in laying cages at 19 wk for a 50-wk production period. In Experiment 1, two hens were placed in each cage and there were three treatment groups: both light (L), mixed or 1 heavy and 1 light (X), and both heavy (H). In Experiment 2, three pullets were used per cage; a medium-weight group (M) was included and mixed cages included 1 heavy, 1 medium, and 1 light weight bird. In an ancillary experiment, 50-wk-old hens were also palpated or not palpated for an egg in the uterus over a single 15-day period. Results indicated that differences that were present in initial body weight groups persisted over the 50-wk period in Experiments 1 and 2 with no effect of weight grouping on body weight gain, egg production, and livability. Differences that were associated with weight groups were: age at sexual maturity, egg weight, egg mass, and nervousness score. No differences in mean feather scores were present among weight groups. Comparisons between individual hens of the same relative weight but kept in homogeneous or heterogeneous weight groups failed to indicate competitive advantages or disadvantages in egg production, feathering, and nervousness scores. No significant associations were found between nervousness scores of individual hens and other traits except for total body weight gain in Experiment 1, in which individuals that gained more were less nervous in the X groups (r = -.55). Palpating hens daily for two 15-day periods significantly increased hen-day egg production in Experiment 2 and nonsignificantly in Experiment 1, with no influence of palpation on hen-day egg production, egg weight, or egg mass in the ancillary experiment.

Animal Husbandry↗
PubMed1987

Density and group size effects on caged hens of two genetic stocks differing in escape and avoidance behavior.

Hens of two moderately inbred White Leghorn stocks, known to differ significantly in escape and avoidance behavior, were compared for productivity traits, nervousness, and feather loss when housed four or eight per cage at densities of 348 (high), 464 (medium), and 580 (low) cm2/bird. Differences were found between stocks in sexual maturity, egg production traits, body weights, nervousness, and feather loss. The more nervous strain lost more feathers. Highest density housing depressed performance and increased nervousness and feather loss, but differences were generally lacking between the medium and lowest density housing. Group size effects were not detected for productivity traits, but hens kept in groups of eight had increased nervousness and feather loss. No interactions were detected between stocks and density, stocks and group size, or density and group size.

Animals↗
PubMed1986

Measuring social behavior: social dominance.

Social dominance develops more slowly when young animals are kept in intact peer groups where they need not compete for resources. Learned generalizations may cause smaller and weaker animals to accept subordinate status readily when confronted with strangers that would be formidable opponents. Sexual hormones and sensitivity to them can influence the onset of aggression and status attained. After dominance orders are established, they tend to be stable in female groups but are less so in male groups. Psychological influences can affect dominance relationships when strangers meet and social alliances within groups may affect relative status of individuals. Whether status associated with agonistic behavior is correlated with control of space and scarce resources needs to be determined for each species and each kind of resource. When such correlations exists, competitive tests and agonistic behavior associated with gaining access to scarce resources can be useful to the observer in learning about dominance relationships rapidly. Examples are given to illustrate how estimates of social dominance can be readily attained and some strengths and weaknesses of the various methods.

Aggression↗
PubMed1986

Corticosteroids and other indicators of hens' well-being in four laying-house environments.

Four presumed criteria of well-being were compared using data from hens of four genetic stocks kept in each of four laying-house environments. Differences between strains selected for increased egg mass and unselected control stocks were not detected, and interactions of selection method with housing environment and periods after housing were not found. Plasma corticosteroid concentrations present during the first 2 weeks after housing were higher than those obtained later. Hens kept in 12-hen, low-density floor pens and 6-hen, high-density cages at 2900 and 310 cm2/hen, respectively, did not differ from each other in corticosteroid levels. However, hens in the floor pens and high-density cages had higher levels than did hens in single-hen, low-density cages and those in 4-hen, moderate-density cages (the latter with floor spaces of 929 and 464 cm2/hen, respectively). Mortality was higher and egg mass per hen housed was less in the 6-hen cages than in floor pens, single-hen cages, and 4-hen cages during the 40-week period following housing. Feather damage and loss increased stepwise and significantly with number of hens per cage. Plasma corticosteroid concentrations did not yield results consistent with other criteria of hens' well-being. There is a need to look beyond the results of corticosteroid assays in establishing hens' well-being in widely different environments.

Adrenal Cortex Hormones↗
PubMed1986

Fearful and associated responses of White Leghorn hens: effects of cage environments and genetic stocks.

Three measures of fearfulness were evaluated for hens of four genetic stocks after they had been kept in single-, 4-, and 6-bird cages for 26 or more weeks. Twelve hens of each stock and cage-environment combination were used (a total of 144 birds). Two tests involved latency of hungry hens to feed when confronted with fear-stimulating objects and one test was for latency to recover from induced tonic immobility. Results for the genetic stocks were inconsistent; strains identified as more fearful by a particular criterion were in some cases less fearful by another or did not differ. Hens kept in single-bird cages were either less fearful or showed a nonsignificant tendency, suggesting less fearfulness by all three criteria. Hens kept in 4-bird cages were typically similar in fearfulness to those in 6-bird cages. Fear-related responses were not clearly associated with plasma corticosteroids, body weights, mortality, or number of eggs laid. However, feather loss (in one test) was associated with escape and avoidance behavior of groups; stepwise increases in fearfulness with increasing group size were associated with similar increases in loss of feathers.

Animals↗
PubMed1985

Mating behavior, boar-to-boar behavior during rearing and soundness of boars penned individually or in groups from 6 to 27 weeks of age.

Individual and group-reared boars were compared in two experiments, for treatment effects on mating behavior, growth rate, feed consumption and feed/gain. Soundness also was evaluated in one experiment. Boar-to-boar behaviors were studied in group-penned boars. In Exp. 1, boars were either reared in a group of five or individually from 12 to 27 wk of age, or group-penned from 12 to 19 wk and individually from 1-9 wk. In Exp. 2, boars were either penned individually from 6 to 27 wk, group-penned (eight/pen) from 6 to 27 wk, grouped from 6 to 12 wk and then penned individually, or individually penned from 6 to 12 wk and then group-penned. Beginning at 29 wk of age, boars were tested every 2 wk for mating behavior in the presence of an estrous gilt. Four mating tests were conducted in Exp. 1 and five tests in Exp. 2. Individually penned boars grew faster from 6 to 12 wk old in Exp. 2, but no other treatment effects on growth rate were observed. Treatment had very little effect on mating test behaviors, but individual penning markedly reduced leg soundness. Sheath sniffing first appeared at 16 to 18 wk of age in group-penned boars and was followed closely by anal sniffing. Side nosing increased between 20 and 23 wk. Mounting activity from 12 to 27 wk old was correlated with mating test score in Exp. 1 (.76; P less than .01) and Exp. 2 (.55; P less than .05).

Animals↗
PubMed1985

Corticosteroid levels in white Leghorn hens as affected by handling, laying-house environment, and genetic stock.

Correlation coefficients between handling time and plasma corticosteroid concentration of White Leghorn hens were minimal when times varied from 43 to 161 sec (r = .17; P less than .05, df = 244), and no association was found when blood collection times exceeding 90 sec were omitted (r = -.02, df = 219). Handling times carried to specific endpoints of 30 and 60 sec indicated no difference, but times of 60, 120, 180, and 600 sec were associated with highly significant differences in corticosteroid levels that were inconsistent between genetic stocks. Strains selected for increased part-year egg mass responded less rapidly to handling than did unselected control strains. Confinement of hens for 4 to 6 hr in nests within their own pens caused increases of greater than 30% in corticosteroids as compared to samples obtained from hens caught directly from the floor. Neither floor pen vs. colony cage nor genetic stock differences were found for plasma corticosteroid levels of hens at a mean age of 55 weeks. Adrenocorticotropic hormone stimulation of 63-week-old hens caused an 8.5-fold increase in corticosteroids above basal but failed to elicit differential effects associated with environments or genetic stocks. Nevertheless, hens kept in floor pens had 10.8% higher survival in the laying house and exceeded colony-cage hens by more than 40% in hen-day egg mass for the final 10 weeks of a 40-week laying period.

Adrenal Cortex Hormones↗
PubMed1984

Tonic immobility responses of white leghorn hens affected by induction techniques and genetic stock differences.

Tonic immobility (TI) was induced in about 70% of While Leghorn hens caught and immediately restrained in the dorsal position for a single 15 sec period. Temporary confinement of hens housed in floor pens in single-bird cages prior to restraint reduced initial induction of TI to 46%. Eye closure during TI occurred in less than or equal to 15% of hens and vocalization, jumping up, or both on termination was present about 80% of the time. Induction of TI on first restraint was greater when less support was provided for the hen's body. Latency until first gross leg and head movement after TI induction decreased with increased time required for catching of hens in floor pens, but righting time (until hens stool up) was unaffected. Correlations among the three latency measures revealed the following: between leg and head movement, r .41 to .71 (P less than .01); leg movement and righting, r .51 to .99 (P less than .01); head movement and righting, r -.62 (P less than .05) to .96 (P less than .01). Genetic differences were detected consistently by latency to first gross head movement and by righting time only. Strains selected for part-year egg mass showed more prompt head movement than did unselected controls. Random genetic drift between strains selected alike apparently was responsible for differences in righting time. Although strains within selection schemes differed, crosses between strains did not differ from the mean of the parental strains, providing evidence that genetic variance for righting time tends to be more additive than nonadditive.

Animals↗
PubMed1984

Fear-related responses of white Leghorn hens of several genetic stocks in five-bird cages and associations with quantitative traits.

Hens of 8 genetic stocks derived from a common foundation population were compared at three ages for latency to recover from tonic immobility (TI) and from an avoidance response following exposure to a metronome. Body weight, feather score, and egg-production traits also were measured. A total of 350 hens was involved and individuals of the same genetic stock were kept together in 5-hen cages from 19 to 70 weeks old. The TI and metronome avoidance tests were conducted in three rounds at mean ages of 35, 48, and 61 weeks. Hens of stocks with increased egg mass, resulting from selection, did not differ from unselected controls for TI or avoidance responses. Straincross hens also did not differ from parental strain means for these fear-related behaviors. Time to recover from induced TI decreased with repeated testing at 13-week intervals. Hens exposed to the metronome a second time within the first round recovered more rapidly than did those tested in this way for the first time. Previous indirect exposure to the metronome also resulted in reduction in avoidance time. Correlation analysis revealed only a moderate association between TI and avoidance responses (r = .23, P less than .01). Avoidance responses were not associated with any other quantitative trait in the 5-hen cage environment. Duration of TI was moderately associated with body weight (r = .22, P less than .01) and had a complex relationship with total egg mass produced, which was associated with the interval in cages prior to testing. There was no apparent correlation of TI and egg mass when TI was measured on 35-week-old hens, heterogeneity of correlations was present among genetic stocks tested at 48 weeks, and a negative association was detected when TI tests were conducted at 61 weeks (r = -.46, P less than .01).

Animals↗
PubMed1983

The effect of rearing environment on sexual behavior of young beef bulls.

Fifty-eight Polled Hereford bull calves were weaned at an average age of 196 d. They were penned individually after weaning and contact was limited to fenceline exposure to bulls in adjacent pens, except when grouped for weighing every 28 d. Six months after weaning they were allotted to one of the following 10-wk rearing treatments: 1) individually penned; 2) individually penned, but exposed to a heifer in estrus for 30 min every 2 wk; 3) group penned; 4) group penned, but each bull exposed to a heifer in estrus for 30 min every 2 wk. The week after allotment was designated wk 0. All 58 bulls, penned together after wk 12, had single-bull mating tests during wk 10, 22 and 32 and multi-bull mating tests during wk 12, 24 and 34. Mean serving capacity and mean serving efficiency were both greater (P less than .05) for individually-penned bulls than for group-penned bulls during the first single-bull and the first multi-bull mating test. No significant serving-capacity differences were present in subsequent single-bull or multi-bull mating tests, but serving efficiency was greater (P less than .05) for group-penned bulls in all subsequent tests, except the last multi-bull mating test. Mean serving capacity was greater (P less than .05), as was mean serving efficiency (P less than .01), for bulls in single-bull mating tests than for those in multi-bull tests. Exposure to heifers during rearing did not affect libido or mating ability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Reproductive development in young boars exposed to sexually mature, nonpregnant sows and gilts.

Thirty Yorkshire boars were allotted by litter to one of two treatment groups. Fifteen boars were reared, from 14 to 22 wk of age, in fenceline contact with mature sows and gilts that were randomly exhibiting estrus. Fifteen littermates of these boars, reared without exposure to females, served as controls. Boar-to-boar sexual behaviors were observed 1 hour daily from 16 to 22 wk of age. At ages 14 to 30 wk, boars were weighed at 4-wk intervals. Five boars per treatment were slaughtered when 22 wk old and twelve others (six per treatment) when 30 wk old. Vesicular gland, bulb of the prostate gland, bulbourethral gland, and each testis, cauda epididymis, and combined caput and corpus epididymis were closely trimmed and weighed. Left cauda epididymal sperm and left testis elongated spermatids were determined by homogenization and hemacytometer counting. At 26, 30, and 38 wk of age, boars were tested for mating efficiency by exposure to an estrous gilt. Boars exposed to females tended to be lighter at 22 wk and were lighter at 30 wk (P<.05). Total male-to-male sexual acts from 16 to 22 wk were correlated with mating-efficiency score at 26 and 30 wk (r = .69 and .68, respectively; (P<.05)). Correlation between testicle size and total testicle elongated spermatids was high at 30 wk of age (r = .92; P<.001). Results indicated that exposing young boars to mature females had limited effects on the boars' reproductive development; however, there were strong indications of a relationship between boar behavior during rearing and postpuberal mating performance.

Journal Article↗
PubMed1981

Agonistic and nonagonistic behaviors of pullets of dissimilar strains of White Leghorns when kept separately and intermingled.

Agonistic and nonagonistic behaviors were compared for pullets of two white Leghorn strains. One strain had been selected for part-year egg production; the other was the unselected control from which the selected strain was derived. There were two experiments in which the strains were kept separately and intermingled in laying-house floor pens. The selected strain had social dominance over the control at 5 months (before sexual maturity), but that dominance had diminished or disappeared when strangers of the two strains were placed together at 17 months. Nevertheless, because of social inertia, selected strain pullets maintained undiminished dominance over control pullets for the entire laying year when they were kept together from housing time onward. Selected strain females had more aggressive acts, more feeding activity, and spent less time resting than control females in both separated- and intermingled-strain housing environments. When pullets of the two strains were kept together, the relative frequencies of their agonistic behaviors were changed, but nonagonistic activities were not altered. Pullets had increased frequencies of pecking and fighting, but not of chases and threats, when they were hungry and feeding. Pullets with higher social status had more feeding activity when feed was constantly available, but that was not apparent when all were hungry and feeding. Preening activity increased as pullets aged.

Aggression↗
PubMed1977

Social status and sex ration effects on mating frequency of cockerels.

Cockerels of 3 early- and 3 late-maturing strains of White Leghorns were observed for agonistic and mating behavior while housed with pullets in floor pens. All male strains were equally represented in each of 6 flocks; replicated flocks contained 6, 12, or 18 males with male:female rations of 1:24, 1:12, or 1:8, respectively. Differences associated with selection for early or late sexual maturity were not detected for either social status or mating frequency. Contrary to expectation, social status of cockerels had little effect on frequency of mating. Flocks with fewer males had lower fertility, but sex ratios (in the range used) had no effect on frequency of mating of individual males. Implications of these results are discussed.

Agonistic Behavior↗
PubMed1975

Fertility from natural matings influenced by social and physical environments in multiple-bird cages.

Various social and physical environments were tested for effects on fertility using three White Leghorn strains in multiple-bird cages. Familiarizing breeder males with the cage environment before introducing females had no appreciable effect. Area per bird (560 vs. 1130 cm.-2) and cage height (40 vs. 80 cm.) were not detected as significant variables. Firmer wire flooring and previous mating experience of males appeared to confer advantages in establishing fertility.

Animals↗