Histomorphometrical changes of oviduct during the long-term exposure of breeder hens to extra thyroxine.

In this research a 100 day long treatment period was considered to unmask the probable adverse effects of long-term induced hyperthyroidism on histomorphometrical attributes of the oviduct in broiler breeder hens. A total of seventy 47-week-old Cobb 500 breeder hens were randomly allotted to two treatment groups (5 replicates of 7 hens each). Thyroxine (T4) was orally administered to the hyperthyroid group (0.3 mg/bird/d) for 100 consecutive days; whereas the control group received drinking water only throughout the trial. At 64 weeks of age, 2 birds per replicate were killed by cervical dislocation and their oviducts were removed. For histomorphometrical observations, segments were taken from five different regions. After tissue preparation and staining with haematoxylin and eosin, histological layers were evaluated using light microscopy. The assessment of histomorphometrical characteristics of oviduct showed the height of mucosal folds in the magnum, thickness of mucosal folds of the magnum and uterus, thickness of tunica muscularis in the magnum and vagina, epithelial thickness of the isthmus and vagina, and uterine tubular glands percentage were decreased in the hyperthyroid birds compared with the control counterparts. The results showed long-term induced hyperthyroidism was associated with a decrease in a number of histomorphometrical traits in different regions of the oviduct. Some studies should be done to clarify to what extent the long-term maternal hyperthyroidism might affect the egg production, fertility rate, duration of fertility, and sperm penetration rate to make a final decision on exploitation of this preventative treatment to diminish the ascites incidence in progeny chicks.

The relationship between growth hormone polymorphism and growth hormone receptor genes with milk yield and reproductive performance in Holstein dairy cows.

The aim of this study was to investigate the potential association between growth hormone GH/AluI and growth hormone receptor GHR/AluI polymorphisms with milk yield and reproductive performances in Holstein dairy cows in Iran. Blood samples of 150 Holstein cows were collected and their genomic DNA was extracted using Gene-Fanavaran DNA extracting kit. Fragments of the 428 bp of exon 5 growth hormone (GH) gene and the 342 bp of exon 10 growth hormone receptor (GHR) gene were amplified using the polymerase chain reaction (PCR) method. PCR products were digested by the AluI restriction enzyme and electrophoresed on 3% agarose gel. Continuous and categorical data were analyzed using linear mixed models through Proc MIXED and logistic regression models through Proc GENMOD of SAS software, respectively. The results showed no relationship between the examined traits and GH/AluI or GHR/AluI genes. A significant relationship was found between GH/AluI polymorphism and dystocia, but the presence of the GH-L allele reduced the incidence of dystocia. The results suggest that the GH-LL genotype reduces dystocia probably by affecting the release of growth hormone; nevertheless, further studies will be needed to examine the relationship between dystocia and GH genotypes.

Improvements in semen quality, sperm fatty acids, and reproductive performance in aged Cobb 500 breeder roosters fed diets containing dried ginger rhizomes (Zingiber officinale).

Exposure to high levels of polyunsaturated fatty acid predisposes spermatozoa to lipid peroxidation, resulting in their decreased fertility. Ginger powder (GP), which is high in antioxidative compounds, was fed to aged breeder roosters to improve their reproductive performance. Seventy-five 52-wk-old Cobb 500 breeder roosters randomly received either 0 (GP0), 15 (GP15), or 30 (GP30) g of GP/kg of diet for 14 consecutive wk, during which time their seminal characteristics were evaluated every 2 wk. At the end of the trial, semen samples were tested for determination of sperm fatty acid (FA) concentration and seminal plasma total antioxidant capacity. Furthermore, sperm penetration was assayed, and using 225 artificially inseminated hens, fertility and hatchability rates were determined. Dietary GP improved sperm forward motility, live sperm percentage, and sperm plasma membrane integrity. These were associated with a decrease in the percentage of abnormal sperm. The seminal TBA reactive species concentration was lower in birds belonging to the GP30 treatment in comparison with those in the GP15 and GP0 treatments. The feeding of GP resulted in overall decreases and increases in sperm saturated and unsaturated FA, respectively. The n-6:n-3 FA ratio of sperm was decreased in the GP30 group in comparison with controls. The highest levels of sperm C20:4(n-6) and C22:6(n-3) FA were recorded in the GP15 and GP30 treatments, respectively. A higher percentage of sperm C22:4(n-6) FA was found in GP-fed roosters. Seminal plasma total antioxidant capacity was considerably improved by the GP15 and GP30 treatments. Further, a higher number of perivitelline membrane sperm penetration holes was recorded for the GP30 treatment in comparison with the GP15 and GP0 treatments. Interestingly, although hatchability, chick quality, and embryonic mortality were not affected by dietary treatment, fertility rate was improved by the feeding of GP. In conclusion, dietary GP improved most of the seminal characteristics evaluated in aged roosters of this study, suggesting that it has potential for use in attenuating age-related subfertility in senescent male commercial broiler breeders.

Association between dry period length and lactation performance, lactation curve, calf birth weight, and dystocia in Holstein dairy cows in Iran.

In this study, 65,971 lactations on 41,842 cows in 64 herds were used to determine the association between dry period length (DPL) and lactation performance, lactation curve, calf birth weight, and the incidence of calving difficulty during the subsequent parity in Holstein dairy cows in Iran. The length of the dry period was classified into 7 categories: 0 to 35d, 36 to 50d, 51 to 60d, 61 to 70d, 71 to 85d, 86 to 110d, and 111 to 160d. Cows with the standard DPL (51 to 60d) produced more 305-d milk, fat, and protein over the next lactation compared with those with shorter dry periods. Shorter dry periods (0 to 35d and 36 to 50d) were associated with lower initial milk yield, steeper inclining and declining slopes of the lactation curve, and higher milk persistency compared with dry period length of 51 to 60d. Peak lactation was achieved later in cows with 0- to 35-d and 36- to 50-d dry period length than in those with dry period length of 51 to 60d. We also observed a relationship between DPL and calf birth weight: smaller calf birth weight was recorded with a dry period of 51 to 60d compared with longer dry periods. The incidence of calving difficulty did not differ in cows with 51- to 60-d dry period compared with cows with 0- to 35-d and 36- to 50-d dry periods. In conclusion, the results of this study did not support previous findings that suggested a shorter dry period could be beneficial to dairy production.

Prestorage in ovo injection of biological buffers: an approach to improve hatchability in long-term stored eggs.

A hypothesis was tested that the in ovo injection of biological buffers may reinforce the buffering capacity of albumen, thereby withstanding the increase in albumen pH during storage and improving hatchability and chick quality in long-term stored eggs. Hatching eggs (n = 2,420) were randomly assigned to 11 treatment groups (4 replicates of 55 eggs each) and injected (d 1) with distilled water, 25 or 50 mM HEPES (H25 and H50), Bicine (B25 and B50), Tris (T25 and T50), and Bis-Tris-propane (BTP25 and BTP50) solutions or were not injected (intact: control; or pricked with a needle: N). The eggs were then stored for 14 d during which the egg internal characteristics were evaluated at 1, 2, 3, 4, 5, 8, and 13 d of storage (n = 924 in total) and the remaining eggs (n = 1,496) were incubated. A decrease in albumen pH was found for H25, H50, B50, and BTP25 groups from 2 through 5 d postinjection. Eggs receiving H25, H50, and B50 recorded a higher albumen index (at 13 d of storage) and Haugh unit (between 8 and 13 d of storage) compared with the control. Interestingly, the hatchability of fertile eggs was influenced by the treatment effect (P = 0.0001) where the eggs receiving H25 (88.3%), H50 (88.9%), B50 (88.4%), and BTP25 (87.6%) recorded higher values than that of control (82.1%), associated with a decreased early embryonic mortality rate (P < 0.0001). In ovo injection of Tris buffer, however, profoundly decreased the hatchability (47.2 and 29.0% for T25 and T50, respectively) and percentage of first-grade chicks (67.5 and 63.6% for T25 and T50, respectively) compared with the control (90.1%). In conclusion, prestorage in ovo injection of H25, H50, B50, and BTP25 improved hatchability in long-term stored eggs in which a decreased albumen pH during the d 2 through 5 of storage period might be involved.

Genetic relationship of conformation traits with average somatic cell score at 150 and 305 days in milk in Holstein cows of Iran.

Genetic, environmental, and phenotypic correlations among average somatic cell score (SCS) at different stages of lactation and conformation traits were estimated. Data consisted of the lactational average of SCS at 150 (SCS(150)) and 305 (SCS(305)) d in milk and 19 conformation traits recorded on 57,154 primiparous Holstein cows, that calved from 1996 to 2009 in 119 herds in Iran. Variance components were estimated using the restricted maximum likelihood procedure based on multiple-trait animal models. Udder depth (-0.32), fore udder attachment (-0.22), and udder width (0.34) showed moderate genetic correlation with SCS(150). Heart girth (0.17), body depth (0.14), chest width (0.26), and angularity (0.19), showed modest genetic correlation with SCS(150). The estimated heritabilities for SCS(150) and SCS(305) were 0.06 and 0.08, respectively. The heritability of the conformation traits ranged from 0.09 to 0.29. Genetic and environmental correlations between SCS(150) and SCS(305) were very high (means ± SE; 0.99±0.01 and 0.89±0.01, respectively), which indicates that recording SCS over a shorter period of lactation is an alternative approach for involving many herds in SCS data collection. The low heritability of SCS indicated that indirect selection for some of udder and body traits might be helpful to reduce the SCS. Additionally, selection for udder traits may help reduce SCS in developing countries where SCS data are sparsely recorded.

Dietary inclusion of dried tomato pomace improves the seminal characteristics in Iranian native roosters.

Because of a paucity of information on the effect of tomato pomace in male chickens, a study was undertaken to determine the influence of dietary inclusion of dried tomato pomace (DTP) on seminal characteristics in Iranian native breeder roosters. Fifty-four roosters (24 wk old) were randomly allotted to 3 treatment groups and received either a basal diet without DTP (T(0)), or a diet containing 15% (T(15)) or 30% (T(30)) DTP for an 8-wk-long experimental period. Semen samples were obtained weekly by abdominal massage to evaluate the seminal characteristics. Dietary inclusion of DTP increased sperm concentration, accompanied by a decreased seminal volume (P ≤ 0.05). The percentage of live sperm in ejaculate was increased in T(15) and T(30) groups, but sperm forward motility was not affected by DTP inclusion. A decreased percentage of abnormal sperm and improved membrane integrity (as determined by the hypoosmotic swelling test) were observed in T(15) and T(30) groups. Lower concentration of thiobarbituric acid reactive substances (as an index of sperm membrane lipid peroxidation) was recorded in roosters fed DTP. A diet × time (wk) interaction was also found for most of seminal characteristics, except for the sperm forward motility (P ≤ 0.05). The results indicated that dietary inclusion of DTP up to 30% improved seminal quality attributes within 4 to 5 wk in roosters; however, the underlying mechanism(s) warrants further study.

Using an incomplete gamma function to quantify the effect of dystocia on the lactation performance of Holstein dairy cows in Iran.

The aim of the present study was to estimate the effect of dystocia on lactation performance, using an incomplete gamma function. Data from March 2000 to April 2009 comprising 100,628 lactations of 65,421 cows in 204 dairy herds collected by the Animal Breeding Center of Iran were used. Of 100,628 births, 91.8% required no assistance, whereas 8.2% required assistance of some sort. Factors associated with the presence of dystocia were calving season, calving year, herd, calf sex, parity, and age of dam. Peak yield for primiparous cows with dystocia at calving occurred on d 87.2 [standard error (SE) 0.47], and for primiparous cows with easy calving, the peak of lactation was on d 83.3 (0.25). Peak yield was lowered by 0.39 (SE 0.07), 2.20 (SE 0.15), 2.22 (SE 0.21), and 2.54 (SE 0.32) kg for cows with incidence of dystocia compared with normal cows in parity 1 to 4, respectively. Dystocia was associated with decreased 305-d lactation performance in all parities, mostly in early lactation. Although more difficult births occurred in heifer calvings, loss in lactation performance was greater in second or later lactations following a difficult birth.