1. The effects of antigen (Ag) injection on the distribution of lymphocyte populations of Cornell K‐strain male chickens were studied.
2. Two experiments were conducted. In the first, chickens were injected with Brucella abortus (BA), a purported T‐independent antigen. In the second, chickens were injected with sheep red blood cells (SRBC), a T‐dependent antigen. Peripheral blood lymphocytes (PBL) and spleen lymphocytes isolated at 0, 3, 6, 9, 12 and 24 h following Ag injection were stained with monoclonal antibodies (mAb) detecting B‐lymphocytes, CD4+ and CD8+ cells.
3. B‐lymphocytes in the blood or spleen showed no significant changes following either BA or SRBC injection. In contrast, CD4+ cells were decreased in the blood and increased in the spleen following BA and SRBC injections. CD8+ cells were decreased in both blood and spleen following BA injection but were unchanged in either blood or the spleen following SR8C injection.
4. These results indicate that there is a change in both spleen and circulating lymphocyte populations, especially T‐helper cells, following Ag injection. T‐helper cells are apparently the primary population involved in the initiation of humoral immunity. 相似文献
1. Growth, food intake, and food preference were measured in two experimental lines (White Rocks and White Leghorns) of chickens fed diets varying in content of lysine, methionine, or tryptophan. Diet A was balanced in all amino acids, while the remaining 6 diets were moderately ( ~ 30%) or slightly ( ~ 15%) deficient in either lysine, methionine, or tryptophan relative to NRC recommendations for broiler diets.
2. Body weight and food utilisation efficiency of White Leghorns at 10 d of age were not affected by diet, whereas the lower concentrations of lysine and methionine depressed these traits in White Rocks.
3. Tryptophan deficiency reduced food intake of White Leghorns, but not White Rocks.
4. With choice feeding of balanced and deficient diets from day 10 to 16, preferences between the diets were minimal for White Leghorns, whereas for White Rocks there was an almost immediate preference for the balanced diet, followed by lack of preference or preference for the deficient diet.
5. Apparently for some genetic stocks there is rapid adjustment to deficiencies in these amino acids with overconsumption, followed by compensation for preference of the balanced diet. The response, however, will vary depending on the deficient amino acid. 相似文献
1. Differences were found among eight populations of White Plymouth Rock pullets in the frequency of broken eggs.
2. The shells of such eggs were thinner than those of intact eggs in seven of the populations.
3. The number of defective eggs, the specific gravity of the eggs, and the percentage hen‐day egg production of normal eggs were significantly correlated within populations with the incidence of broken eggs.
4. No significant correlations were found within populations between the incidence of egg breakage and either egg weight, body weight, or shank length. 相似文献
Lactation in the mare is associated with changes in the release of metabolic as well as reproductive hormones. Plasma glucose concentration is constantly reduced in lactating compared with non-lactating mares. Several metabolic signals have been proposed to link nutrition and somatic metabolism with reproductive function. The following experiment was performed to study the effect of acute hypoglycaemia on the release of insulin-like growth factor-1 (IGF-1) and luteinizing hormone (LH) in cyclic mares. Different doses of insulin (0.1 and 0.2 IU/kg body weight) were given to induce a decrease in plasma glucose concentration, as existent in lactating mares. All horses treated with insulin developed a hypoglycaemia over a time period of nearly 10 h. The IGF-1 and LH were analysed before and after insulin administration. At no point of time, a significant difference between the two insulin treatments and the control treatment was observed. Therefore, the hypoglycaemic horse is apparently able to provide the brain with sufficient glucose. Short-term hypoglycaemia does not affect the hypothalamo-pituitary-ovarian axis, and concentrations of IGF-1 and LH remained stable during insulin-induced hypoglycaemia. An acute change in plasma glucose concentration is thus not or at least not the only metabolic signal that links nutrition and somatic metabolism with reproductive function in the horse mare. 相似文献
The practice of horse rugging has important implications for horse welfare and performance, but in Australia, rugging practices have not been properly documented. The objective of this study was to obtain an understanding of Australian horse rugging practices. An online survey reviewed the management of 2659 Australian horses over 12 months. Of the reported horses a total of 84.8% were rugged, although most owners (69.5%) indicated that they were unsure whether horses needed to be rugged at all. Rugging was felt by 59.8% of owners to be a requirement for horses in competition. Riding and competition were significantly associated with the use of rugs. Nearly all respondents (89.0%) felt that ‘over-rugging’ was a concern. However, 4.8% of owners would use up to 4 rugs at any one time on their horse and 21.4% of horses were still rugged in temperatures above 20°C in Australia. Many Australian horse owners (42.8%) also believe that horses feel cold if they are not rugged. Anthropomorphism when it comes to rugging horses cannot be justified as the horse has a much wider thermoneutral zone (TNZ) than humans. Australian climate, owner opinions, equestrian discipline and whether a horse is used for riding influence Australian horse rugging practices. However, current practices are based on limited available research and are not necessarily to the benefit of the horse. The major limitation was that the survey likely attracted respondents who are interested in the topic creating a self-selection bias. 相似文献
This study evaluated the reproductive performance of gilts inseminated at three intervals before ovulation (0-12, 13-23, 24-30 h) with sperm doses (SD) stored for 0-48 and 96-120 h. A total of 218 PIC Camborough 22 gilts were inseminated once with SD of 1.5 x 10(9) sperms. Pregnant gilts (n = 166) were slaughtered 30.8 +/- 3.7 days after artificial insemination. The number of corpora lutea (CL) and total embryos (TE) was counted. Pregnancy rates (PR) were analysed by chi-square test. TE and embryonic survival (ES), obtained as the ratio between viable embryos and CL, were analysed by GLM procedure (SAS) and mean values were compared by Tukey's test. Pregnancy rate was similar among artificial insemination-ovulation (AIOV) intervals when semen was stored for 0-48 h. However, the lowest PR was observed in the 24-30 h AIOV interval with storage time (ST) of 96-120 h (p < 0.05). There was a significant effect of the interaction between ST and AIOV (p < 0.05) on TE and ES variables. Total embryos and ES did not differ (p > 0.05) among AIOV intervals in ST of 0-48 h. However, gilts inseminated at 24-30 h AIOV interval with ST of 96-120 h showed a reduction of 6.7 embryos (p < 0.05) compared with gilts in the same interval inseminated with semen stored for 0-48 h. ES for the 24-30 h AIOV interval and ST of 96-120 h was lower than that observed in the other groups (p < 0.05). 相似文献
The objective of this study was to characterize follicular dynamics in pre-pubertal, pubertal and post-pubertal periods, as well as the effect of high-energy intake on follicular development and age at puberty in heifers. Thirty-one Nelore (Bos indicus) heifers, 6 months old, were randomly assigned to receive two different diets: one of low (GI) and other of high dietary energy intake (GII). Animals were evaluated in relation to body weight gain by being weighed every 21 days. Heifers were evaluated every other day by real-time linear ultrasonography to characterize ovarian structures development from weaning to post-pubertal period. Blood samples were collected to determine plasmatic concentrations of progesterone by RIA method. The ovulation was determined when progesterone concentrations were >1 ng/mL in three consecutive samples, and by ultrasound images of corpus luteum; and oestrous behaviour in some animals. Age at puberty differed among heifers of GII (17.00 +/- 0.46 months) compared with heifers of GI (19.87 +/- 0.47 months; p < or = 0.05). Maximum size of the dominant follicles at pre-pubertal period was greater in GII heifers than in GI (10.52 +/- 0.33 and 9.76 +/- 0.15 mm, respectively; p < or = 0.05). As heifers approached first ovulation time, size of dominant follicle increased (11.75 +/- 0.37 mm for GI and 12.52 +/- 0.91 mm for GII; p < or = 0.05). Body weight at puberty was not different in both groups (302.33 +/- 27.31 kg for GI and 326.19 +/- 27.78 kg for GII heifers; p > 0.05). We conclude that animals receiving high dietary energy intake attained the puberty earlier and the development of follicles were different than in low dietary energy intake. 相似文献