Robert P. Breitenbach

Effect of limited food intake on cyclic annual changes in ring-necked pheasant hens.

Annual changes in body weight, food intake, lipid indices, egg laying, and organ weights are reported for ring-necked pheasant (Phasianus colchicus) hens maintained on wire, on ad libitum and limited amounts of a high protein diet. Birds were autopsied at 3-month intervals for organ weight data. In control birds, body weights rose gradually throughout fall and early winter, rapidly increased in February and March, and reached a maximum in April. Food intake in the control pheasants closely paralleled the changes in body weights, but greatest intake occurred a month later coincident with the period of maximum egg production. Birds on limited intake maintained their body weight until the early reproductive season when a decline in weight occurred. Egg laying was markedly depressed and delayed in limited intake birds, although egg size and composition were normal. Laying in limited intake pheasants was 9 percent of that of control birds. Depot fat was found to parallel closely the changes in body weight and food intake. Liver lipids were lower in limited intake birds during all but the reproductive season. Plasma lipid values were statistically higher in limited intake birds during the nonreproductive season. The liver and intestine weights were greater in the limited intake birds. It is suggested that these data represent changes which help increase alimentary efficiency.

Pituitary Prolactin Levels in Laying, Incubating and Brooding Pheasants (Phasianus colchicus).

Summary Pituitary glands were removed from hen pheasants in various stages of reproduction—laying, non-laying, incubating and brooding and bioassayed for prolactin content. Prolactin levels rise rapidly during early incubation from levels observed in laying birds. Peak prolactin levels were noted from 8th to 12th days incubation. Prolactin content declined rapidly during latter portion of incubation and throughout the first 11 days following hatching. This occurred despite the fact that late incubation and post-hatching are periods of most intense brooding activity. Non-laying birds showed slightly higher pituitary prolactin levels than did laying birds. Pituitaries of 2 broody cocks were examined after 20 days incubation and showed less prolactin than pituitaries of 2 non-broody control cocks. It is suggested that early high prolactin levels condition the bird for subsequent brooding stimuli. The relationship to control mechanisms is discussed.

Vitamin C in Lymphoid Organs of Rats and Cockerels Treated with Corticosterone or Testosterone

Summary Immature rats and cockerels were injected for 14 days with 0.05-5.0 mg of testosterone propionate or corticosterone, and the concentration and oxidation state of vitamin C in their lymphoid organs was measured. The total vitamin C concentration (ascorbate + dehydroascorbate) in the lymphoid organs of both animals decreased after hormone administration, but to a greater extent in rats than in cockerels. These changes appear to be independent of any direct hormonal influence on vitamin C biosynthesis. Significant and marked changes in the oxidation state of lymphoid organ vitamin C occurred after lympholytic steroid hormone treatment; the percentage of dehydroascorbate increased and that of ascorbate decreased. After hormone treatment the largest percentage change from controls (more than 100% increases in percentage dehydroascorbate) occurred in the central lymphoid organs, the bursa and thymus, rather than in the spleen or lymph nodes. Much lower dose levels of corticosterone (0.05 mg) than of testosterone propionate (5.0 mg) were required to produce this shift in the oxidation state of lymphoid organ vitamin C. We suggest the ascorbate-dehydroascorbate system in the lymphoid organs is an integral portion of the physiological mechanisms operative during hormonal modulation of the growth, metabolism, and function of the lymphoid organs.

Effects of dietary calcium levels on egg production and bone structure of pheasants.

Captive pheasant (Phasianus colchicus) hens fed various levels of calcium produced more eggs when the amount of calcium in the diet was increased. Birds on high calcium diets would have been able to produce two adequate sized clutches of eggs; birds which had received very little dietary calcium (0.5 percent) could not have produced two clutches. The amounts of calcium, phosphorus, and ash found in femurs varied little between birds fed different levels of calcium. Osteoporosis was detected in female pheasants fed low levels of calcium. Femurs of these birds had enlarged haversian canal systems, as shown by total space occupied by canals, mean canal size, and the amount of cortex present. Bones of birds fed 0.5 percent and 3.2 percent calcium were significantly different in these respects; inconclusive data were obtained from birds fed intermediate levels of calcium. Cocks on low calcium diets showed some evidence of osteoporosis; those receiving adequate calcium showed none. Recent studies have shown that pheasants can select calcium grits when unusual needs arise; thus pheasants might get enough calcium during the breeding season even in low-calcium habitat. To determine whether calcium supplies are adequate it is suggested that breeding females from areas of low populations be examined for evidence of osteoporosis. The purpose of this study was to determine the effects of various dietary levels of calcium on (1) egg production and (2) the physiology of the pheasant hen, with emphasis on postlaying osteoporosis. Knowledge of changes in the skeleton and endocrine system that result from calcium deprivation is essential to evaluation of calcium as a factor influencing pheasant range extension. Leopold (1931:125-126) first suggested that the level of calcium in the soil may significantly influence the distribution of pheasants in North America. The results of later studies supported this hypothesis (McCann 1939 and 1961, Dale 1954, Dale and DeWitt 1958, Greeley 1962). However, the precise relationship between calcium levels and pheasant abundance remains unknown. The subject was recently reviewed by Korschgen (1964:176-177), Harper (1964: 264-265), and Harper and Labisky (1964: 722-723). Even in calcium-rich pheasant range, natural foods alone may not provide enough calcium to meet needs during the reproductive period. Dale (1954:318) found that the amount of calcium obtained from natural plant and animal foods supplied less than 20 percent of the amount required for optimum reproduction. However, pheasants may meet special calcium needs during the reproductive season by increasing mineral consumption (Dalke 1938:54, Trautman 1952:27). The hens ability to select calcium-bearing grits, as demonstrated by Sadler (1961:341), enables her to increase consumption of calcium before and during the egg-laying period. Korschgen (1964:168) showed that during egg production, pheasant hens throughout the Midwest heavily supplement their diet with calcium-bearing grit or snails. Because of such findings, Korschgen (1964:177-178) and Harper and Labisky (1964:730) expressed considerable doubt about the importance of calcium as a factor limiting pheasant distribution. Eggshell formation requires substantial amounts of calcium, which constitutes 39.2 SThis project was supported by funds from Federal Aid to Wildlife Restoration Project, Surveys and Investigations Projects, Missouri 13-R.

Studies of incubation and broody behaviour in the pheasant (Phasianus colchicus

Abstract Evidence is presented which indicates that hen pheasants show responses other than incubation as incubation progresses. Some types of behaviour are observed only by hens in the advanced stages of incubation. Other responses may be detected throughout incubation. The development of this behaviour in the first half of incubation coincides with the rapid rise in the content of prolactin in the pituitary. Experimental reduction and prolongation of the incubation period yield data which suggest that prolactin has a conditioning effect on the brooding hen. Prior to this conditioning, a premature hatching stimulus does not elicit brooding behaviour in hens with no previous breeding experience. Delay of the hatching stimulus does not appear to affect chick acceptance. The typical behaviour of the pheasant cock to the incubating hen and the chicks is described. The few cocks which incubated eggs showed the same development of behaviour and broody activity which was observed in hens.

SUSTAINING VALUES OF EMERGENCY FOODS FOR BOBWHITES

Sustaining values of foods that might be useful to bobwhites (Colinus virginianus) under emergency conditions were tested by feeding penned bobwhites single foods during fall and winter and observing their survival and condition. In the pilot study, 11 foods were tested for 38 days; 132 bobwhites of mixed sex and age-groups were employed. In the principal study, 6 of these foods were tested for 14 days on 84 young birds of both sexes. On the basis of food consumption, weight performance, depot fat, lipid levels, and other physiological measures, pearl millet (Pennisetum glaucum), sassafras (Sassafras albidum), foxtail millet (Setaria italica), and milo (Sorgum vulgare) had the highest sustaining values among the foods tested. Their values exceeded those of such well- known winter staples for bobwhites as corn (Zea mays) and Korean lespedeza (Lespedeza stipulacea). Sericea (Lespedeza cuneata), rose (Rosa multiflora) hips, and smooth sumac (Rhus glabra) ranked lowest. The purpose of this study was to com- pare the sustaining values of certain native and cultivated bobwhite foods that might be useful under emergency conditions. Performance of bobwhites sustained on these foods was compared with those liv- ing on foods known to be staples for quail. Food consumption, weight performance, and several measures of the physiological condition of the birds were used as indices to the sustaining value of each food tested. These data were supplemented by chem- ical analyses of the foods. The study was similar in some respects to those of Erring- ton (1931, 1937) and Williamson (1955, 1956, 1957). Our study was prompted by Stanfords discovery that many Missouri bobwhites fared poorly on the emergency foods avail- able to them during a prolonged period of snow cover in the winter of 1959-60. Some bobwhites were found starving, although their crops were full of sericea seeds. This paper is a joint contribution from

BREEDING POTENTIAL OF SUBADULT WILD TURKEY GOBBLERS

Testes were collected from adult and subadult eastern wild turkey gobblers (Meleagris gal- lopavo silvestris) killed during Missouris spring turkey seasons of 1964 and 1965, in order to deter- mine the breeding potential of the subadult gobblers. Subadults were separated from adults on the basis of weight, spur and beard length, and retention of the 9th and 10th juvenile primaries. Rectrix replacement and progress of the postjuvenile or annual molt were helpful in separating age groups. A positive relationship was found between the predominant stage of spermatogenesis and testis weight of subadults. Testes weighing 7 g or more always showed spermatids, but those weighing less than 4 g never showed spermatozoa as the predominant stage. Bursa depths were shallower in birds exhibiting advanced stages of spermatogenesis, but spur length and beard length showed no relation to the stage of spermatogenesis. The sample taken from the testes of subadult gobblers shot during the 1964 and 1965 turkey seasons showed 28 percent (14 of 50) which possessed mature sperm. These data imply that these subadults could be capable of breeding. It is generally assumed that first-year wild turkey males do not breed (reviewed by Mosby and Handley 1943:107). Leopold (1944:160-161) recounted several observa- tions supporting this view. Among domestic turkeys (M. g. gallopavo), on the other hand, gobblers less than 1 year old are con- sidered the most vigorous breeders and are selected over adults for this purpose (Mars- den and Martin 1955:557). Hybrid sub- adult males breed both in pens and in the

Relation of Castration to Fat Stores in Male Pheasants

During 1958 and 1959 we studied the effect of castration on lipids in male gamefarm pheasants confined to outdoor pens. In both years the visceral fat stores of control birds decreased from January to June and then increased. Among the orchidectomized pheasants, visceral fat was minimum from February to April 1958 and maximum thereafter, but did not change seasonally in 1959. Liver and plasma lipid showed no regular periodicity and were not associated with levels of visceral fat nor influenced by castration. The weight of the adrenals in intact pheasants increased 20% from February to June 1958 and then decreased. During 1959 the adrenals of these birds weighed most in April, when they were 30% heavier than in January; subsequently they involuted. In 1958 the seasonal pattern of adrenal weight in gonadectomized pheasants was opposite to that of controls, whereas in 1959 the pattern was like that of intact birds. Thyroid weight was stable seasonally. See full-text article at JSTOR