Broilers from three consecutive hatches were exposed to cool temperatures to amplify the incidence of pulmonary hypertension syndrome (PHS, ascites). The largest apparently healthy individuals on Day 42 were evaluated using minimally invasive diagnostic indices [percentage saturation of hemoglobin with oxygen, hematocrit (HCT), heart rate, electrocardiogram (ECG) Lead II, body weight), then they were subjected to the ongoing pressures of fast growth and cool temperatures to determine which of these indices are predictive of the subsequent onset of PHS. Approximately 20% of the males and females evaluated on Day 42 subsequently developed PHS by Day 51. When data for all hatches were pooled and broilers that subsequently developed ascites were compared with those that did not (nonascitic), body weights, heart rates, and percentage saturation of hemoglobin with oxygen were lower on Day 42 for ascitic than for nonascitic males, and HCT was higher in ascitic males and females than in nonascitic males and females, respectively. Comparisons of the ECG Lead II wave amplitudes for all hatches pooled indicated that RS-wave amplitude was larger in ascitic than in nonascitic males, and that S-wave amplitude was more negative in ascitic males and females than in nonascitic males and females. Necropsies conducted on Day 51 revealed higher right:total ventricular weight ratios in ascitic than in nonascitic broilers, whereas normalizing the left ventricle plus septum weight for differences in body weight generated similar values for ascitic and nonascitic males and females, respectively. These results support a primary role for pulmonary hypertension but not cardiomyopathy in the pathogenesis of ascites triggered by cool temperatures. Values obtained for minimally invasive diagnostic indices on Day 42 also establish predictive thresholds that can be used to evaluate the PHS susceptibility of large and apparently healthy male and female broilers.

Biogenic amines have been implicated in a malabsorption syndrome characterized by decreases in feed efficiency and enlargement of the proventriculus. Two studies were conducted to determine the effects of two common biogenic amines, histamine (HIS) and cadaverine (CAD), on broiler growth and the incidence of pathologies associated with proventriculitis. In the first experiment, broiler chicks were fed diets containing 0, 0.01, 0.05, 0.1, and 0.2% HIS, and in the second experiment chicks were fed diets containing 0, 0.1, and 0.2% HIS, 0.1% CAD, or a combination of 0.1% HIS and 0.1% CAD. Histamine at 0.1 and 0.2% or the combination of HIS and CAD (0.1% each) reduced body weight and feed conversion at 21 d of age. Histamine (0.2%) or the combination of 0.1% HIS and 0.1% CAD increased the circumference of the gastric isthmus 14 and 16%, respectively, and the relative weight of the proventriculus by 21 and 36%, respectively. Histamine and CAD increased the total number, incidence, and severity of gizzard erosion and proventricular ulcers (plaques), and decreased the prominence of gastric papillae by 9 to 108%, depending on the lesion and level of biogenic amine. Dietary HIS (0.2%) increased putrescine by 91% and spermidine by 41% in proventriculus, and dietary CAD increased tissue CAD to detectable levels. Analysis of 49 commercially available, animal by-product feedstuffs suggests that if biogenic amines were the singular cause of proventriculitis, the current industry levels of dietary animal protein (5 to 10%) would not compromise growth performance.

After 21 generations of selection for alternative criteria to change litter size in mice, responses in uterine capacity and ovulation rate were evaluated. Females from Generations 22 and 23 were sampled from 12 lines, representing three replicates of four selection criteria: LS = direct selection on litter size; M = selection on an index of ovulation rate and the proportion of ova shed that resulted in fully formed offspring; UT = selection on uterine capacity measured as litter size from females unilaterally ovariectomized at 4 wk of age; and LC = unselected control. All females in the present evaluation ( a total of 1,932) were unilaterally ovariectomized (either left or right ovary excised) at 4 wk, mated a t 9 wk, and killed a t d 17 of gestation. The number of corpora lutea and number of fetuses were counted to measure ovulation rate and uterine capacity, respectively. Selection in IX, LS, and UT increased ( P < .01) ovulation rate from unilaterally ovariectomized females but by a greater amount ( P < .01) in IX and LS than in UT. Selection also increased ( P < . O l ) uterine capacity of IX, LS, and UT (average response relative to LC = 1.76 pups); response was at least as great in LS and IX as in UT. Direct selection in UT was successful at improving uterine capacity but was no more effective than IX or LS selection. Cases in which ovulation rate limited expression of uterine capacity in UT may have shifted some selection emphasis to ovulation rate and reduced response in uterine capacity.

A study was conducted with broiler breeder pullets to investigate the effects of strain, age at photostimulation (PS), and release from feed restriction at PS on age, BW, ovarian morphology, and carcass characteristics at sexual maturity (point of initiation of lay). Sixty birds of each of 4 strains were used. The 4 types represented a classic strain (A), 2 high-yield strains (B, C), and a roaster strain (D). Photostimulation (8L:16D to 14L:10D) was applied at 2 different ages (21 and 24 wk) to 30 birds of each strain type. Within each of the PS periods, 15 birds of each strain were fed ad libitum (F), and the remaining 15 were feed-restricted (R) following a common feeding schedule. On the day that each bird had its first oviposition, its feed was withdrawn. It was euthanized the following morning by cervical dislocation and organs were collected. Of the 3 main effects, feeding program had the greatest effect on all the parameters measured. Within the 21-wk PS treatment group, R birds reached onset of sexual maturity later than F birds (50.2+/-1.64 vs. 36.6+/-1.01 d, respectively). There were no differences in the age at sexual maturity between R and F birds for the 24-wk PS treatment (28.9+/-0.95 vs. 26.9+/-0.85 for R and F, respectively). These results suggest that by 24 wk, all strains had reached a threshold BW and responded uniformly to PS regardless of feeding program. Feed restriction reduced the number of large yellow follicles (LYF) (diameter >10 mm) (8.43+/-0.23 vs. 9.65+/-0.33 for R and F birds, respectively). Follicle number was not different between birds photostimulated at 21 or 24 wk (9.6+/-0.33 vs. 8.45+/-0.23, respectively). Feed restriction affects sexual development that can be modulated by the PS program.

An artificial neural network was trained to predict the presence or absence of ascites in broiler chickens. The neural network was a three-layer back-propagation neural network with an input layer of 15 neurons (defining 15 physiological variables), a hidden layer of 16 neurons, and an output layer of 2 neurons (the presence or absence of ascites). Male by-products of a breeder pullet line were brooded at 32 and 30 C during Weeks 1 and 2, respectively. The training set for the neural network consisted of data from birds subjected to cool temperatures (18 C) to induce ascites. After training, the predictive ability of the neural network was verified with two new data sets. The second data set was from birds subjected to cool temperatures (18 C). The third data set was from birds subjected to clamping of the pulmonary artery to simulate the physiological processes involved in ascites (the temperature was 24 C). A comparison was made between laboratory diagnostic results and the neural network predicted ascites incidence. The neural network accurately identified the presence or absence of ascites in the first (training) set. Two false positives and one false positive were identified in the second and third verification sets, respectively. The birds identified as false positives were determined to be in the developmental stages of ascites before the occurrence of fluid accumulation. Artificial neural networks were found to effectively identify broilers with and without ascites.