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We studied the effect of lighting during 19 days of incubation on embryonic bone characteristics, gene expression, thyroid hormones, and glucose in Cobb broiler hatchlings. Eggs (2160) were incubated under darkness (control) and green and white lighting (16D:8L and 12D:12L). On 19th day, tibiotarsal length increased under eight hours of white light, and femoral ossified length was longer under eight hours of white and green light. In femur, expression of Alp, Col10a1, and Spp1 increased by 12 h white and 8 h green lighting, and Bglap expression decreased under white. In tibiotarsus, expression of Alp decreased by 8 h lighting (green or white) while Bglap increased by 12 h lighting (green or white). Tibiotarsal expression of Col10a1 increased by 12 h lighting (white and green), and in 8 h green lighting, and Spp1 expression was higher under light illumination. The hatchling blood triiodothyronine concentration in 8 h green lighting was higher than that in control, whereas, thyroxine concentration was lower under 12 h white lighting compared with other treatments. Femoral organic matter to mineral (OM:M) ratio and calcium concentration were higher in the eight-hour white light group than in the control, but tibiotarsal OM:M ratio and calcium and phosphorus concentrations were higher under 12 h white light. The findings indicated that lighting during incubation may impact, both positively and negatively, bone morphology and gene expression. More studies are needed to find the most beneficial lighting system during incubation in chickens. [ABSTRACT FROM AUTHOR]

The aim of this study was to estimate the nitrogen requirements of Holstein suckling calves at 2, 6 and 8 weeks of age. Newborn healthy calves, randomly divided into 2 groups (n=16 per group), were fed with either a starter based on corn or barley. The calves received pasteurized cow's milk in accordance to the herd schedule. The calves were housed in individual metabolic cages and urinary and fecal nitrogen contents were measured in samples collected for four days at 2, 6 and 8 weeks of age. Nitrogen requirement was estimated using the regression analysis. Nitrogen requirement for maintenance at week 2 significantly (P=0.037) differed between the starters, but not at 6 and 8 weeks. However, the nitrogen requirement for maintenance at 8 weeks of age tended to be differ between male and female calves (P=0.075), but not at weeks 2 and 6. Daily nitrogen requirements for maintenance based on the metabolic weight decreased as the calves aged. Nitrogen requirement for growth was affected by the type of grain in the diet at weeks 2 (P=0.068), 6 (P<0.05) and 8 (P<0.05). No effect of sex was found on nitrogen requirements for growth (P>0.05). [ABSTRACT FROM AUTHOR]

The association of birth type (single vs. double) and pregnancy type (single vs. double) with lactation performance and lactation curve was investigated in Holstein cows in Iran. Data of 243298 lactations on 138021 cows in 261 herds collected during January 2000 to December 2012 were used. The average twinning rate was 3.64% and ranged from 1.44% (primiparous) to 5.41% (multiparous). Factors associated with twining were calving season, calving year, herd, and parity. The rate of twinning increased from 2.49% in 2000 to 3.42% in 2012. The probability of twinning was higher in multiparous cows than that in primiparous [Odds ratio (OR) (95% confidence interval (CI))= 3.64 (3.44-3.84) for multiparous vs. primiparous cows]. The probability of twin pregnancy was higher in cows previously delivering twins than that in those delivering singles [OR (95% CI)= 3.17 (3.02-3.34) for cows delivering twins vs. cows delivering singles]. The lactation curve for cows delivering singles in previous gestation and pregnant with twins in subsequent gestation tended to be lower and flatter. The incidence of twin pregnancy was increased as the cow reached its peak yield earlier, and produced more milk at peak lactation. Primiparous cows delivering singletons in their previous gestation and having twins in their subsequent gestation produced more 100-d, 200-d and 305-d milk than those pregnant with singletons. Multiparous cows that delivered singleton in previous gestation and were pregnant with twin in the subsequent gestation, produced more milk during the first 100-d and 200-d of lactation than those pregnant with singles. [ABSTRACT FROM AUTHOR]

BMP15 and GDF9 are two oogenesis specific genes play a pivotal role in female fertility in mammals and potential for improvement of prolificacy in marker-assisted selection. The aim of present research was to investigate the variation and association between BMP15 and GDF9 polymorphism and litter size in Markhoz goats. The sequence variability of the different amplified fragments utilized for genotyping was further investigated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing. Sequencing technology allowed the detection of two nucleotide variations: A both non-functional mutation (G/A) transition at nt 1026 known as P3) and a synonymous mutation at 1049 position which for the first time was found at the BMP15 gene. Also, GDF9 gene exhibited a polymorphism on BcnI site (1159 bp) within exon 2 of amplified PCR products (glutamine/proline). Our analysis using general linear model (GLM) statistical methods showed litter size was significantly influenced by genotypes of GDF9 (P<0.01). Heterozygous genotype showed higher litter size than homozygous genotypes (P<0.01). The conformation of this founding would need large sample size and test to screen in other indigenous goats. [ABSTRACT FROM AUTHOR]

The objectives were to estimate (co)variance components and genetic parameters for lactation curve traits in Holstein dairy cows in Iran. The used data were records on Holstein cows collected during January 2003 to December 2012 by the Animal Breeding Center of Iran (Karaj, Iran). In order to describe the lactation curve, an incomplete gamma function was fitted to 691200 test-day records on 96263 lactations, 377696 test-day records on 52168 lactations, and 182143 test-day records on 24951 lactations for the first three parities, respectively. Lactation curve traits that were analyzed included a scaling factor associated with initial yield, the inclining and declining slopes of the curve, peak time, peak yield, 305-d milk yield and a lactation persistency measure derived from the incomplete gamma function. The estimated heritability of lactation curve traits for the first, second and third lactation ranged from 0.012 to 0.29, 0.017 to 0.15, and 0.02 to 0.13, respectively. Genetic correlations among lactation curve traits for the first, second and third lactation ranged from -0.68 to 0.99, -0.84 to 0.98 and -0.90 to 0.94, respectively. The estimated repeatability of lactation curve traits ranged from 0.07 to 0.40. The moderate to large positive genetic correlations of 305-d milk yield with initial yield, peak yield and lactation persistency suggest that one of these traits could be used as a selection criterion to improve all four traits. However, the peak yield and 305-d milk yield were more heritable than lactation were persistency and initial yield. [ABSTRACT FROM AUTHOR]