Poultry abattoir survey of carcass condemnations in Fars province, southern Iran

Official post-mortem inspection records of poultry in 11 industrial poultry abattoirs in the Fars province, southern Iran, between 20 March 2002 and 19 March 2006 were used to investigate the character and prevalence of poultry loss caused by disease and pathological changes in the province. Linear regression analysis for study of time trend and χ²-test for investigation of seasonal pattern were used as statistical methods. In the study period, 130,967,021 birds were slaughtered. As a result of official veterinary inspection, 959,416 (0.73%) birds were condemned. The condemnation risk was calculated for each quarter in a year. Cachexia and septicemia were the most common reasons for rejection of carcasses and were responsible for 62% of the total condemnations. The condemnation risk due to septicemia increased over the study period from 0.14 to 0.22%. The rejection risk due to overscalding declined over the study period from 0.07 to 0.01%. No trends in time were observed for the other causes of condemnation. In conclusion the majority of condemnations are caused by disease and improving the standard of disease prevention and control on farms is necessary. These results could form the basis of an assessment of trends in condemnations in poultry slaughterhouse and should prove useful to the poultry industry as a baseline data for future comparison.     

Genetic parameters and trends for calving interval in the first three lactations of Iranian Holsteins

Calving records from the Animal Breeding Center of Iran collected from January 1987 to December 2007 and comprising 292,875 calving events of Holsteins from 1,413 dairy herds were analyzed using univariate and bivariate linear animal models to estimate heritabilities and genetic correlations for calving intervals in the first three lactations of Holstein cows. Genetic trends were obtained by regressing yearly mean estimates of breeding values on calving year. Average calving intervals were from 406 to 414 days and decreased over the parities. Heritability estimates for calving intervals varied from 0.03 to 0.04 across the parities. Also, estimates of genetic correlations between calving intervals in different parities were high and ranged from 0.67 to 0.89. The average annual phenotypic trends obtained from fitting linear regression of annual mean calving intervals at parity 1 and 2 were significant (P < 0.01), but the phenotypic trend of calving interval at parity 3 was not significant over the years. On the other hand, there was an increasing genetic trend for calving interval at parity 1, and there were decreasing genetic trends for calving intervals at parity 2 and 3 over the years (P < 0.01). The low estimates of heritability obtained in this study imply that much of the improvement in calving interval traits could be attained by improvement of production environment rather than genetic selection.     

Association of Mycobacterium avium subspecies paratuberculosis infection with milk production and calving interval in Iranian Holsteins

There are inconsistent results for the association of Mycobacterium avium subspecies paratuberculosis (MAP) infection with production and reproduction in dairy cows. Determination of these associations in each region is essential to encourage participation of dairy cattle producers in disease control programs. This study was conducted in Shiraz, southern Iran, to quantify the association of subclinical MAP infection with 305-day milk production and calving interval in Iranian Holsteins. A total of 21 dairy herds were selected for the study and in each herd, quarter milk samples were collected from ten to 12 dairy cows for PCR analysis. Data about parity, calving interval, length of lactation period, total milk production and 305-day milk production were also provided for each animal. Overall, 252 individual milk samples were collected. Herd- and individual-level prevalence of MAP infection were 23.8% (95% CI, 6.2–41.4%) and 3.2% (95% CI, 1.3–5.1%), respectively based on IS900 nested PCR. The results for 305-day milk production revealed a 248 kg reduction in positive cows compared with negative ones (P = 0.009). When cows from positive herds were compared with cows from negative herds, a 335-kg reduction in 305-day milk production (P = 0.005) and a 30-day increase in calving interval (P = 0.057) were observed in the former group. These findings support the previous results that paratuberculosis infection is negatively associated with the performance of the animals.     

Estimation of genetic and phenotypic relationships between age at first calving and productive performance in Iranian Holsteins

Calving records from the Animal Breeding Center of Iran collected from January 1990 to December 2007 and comprising 207,106 first calving events of Holsteins from 2,506 herds were analysed using univariate and bivariate linear sire models to estimate heritabilities and genetic correlations between age at first calving (AFC) and productive performance. Average AFC was 26.48 months in this study. The peak in the frequency distribution of AFC clearly exists coinciding with cows calving for the first time at approximately 25 months of age. Heritability estimate for AFC was 0.34 which was greater than the corresponding values for productive traits. The heritability estimates were low to medium for productive traits which ranged from 0.17 to 0.26 for cows in their first calvings. Except for fat and protein percentages of milk, phenotypic and genetic correlations between AFC and productive performance traits were low to moderately negative. Range of genetic correlations between productive traits was −0.53 to 0.99. Reduction of age at first calving appeared to have a negative effect on first lactation protein and fat percentages; however, it had positive effects on milk yield, fat yield, protein yield and their mature equivalents. It seems that reducing age at first calving to 24–25 months is probably more profitable than reducing age at first calving to an earlier time in Iranian conditions.     

Herd-level prevalence of Mycobacterium avium subspecies paratuberculosis by bulk-tank milk PCR in Fars province (southern Iran) dairy herds

A cross-sectional study was conducted from March to August 2006 in dairy herds in Fars province, southern Iran to determine the herd-level prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) infection. Bulk-tank milk samples were collected from 110 dairy herds in the 3 districts (Shiraz, Marvdasht and Sepidan) of the province. Among study populations, 12 herds (11%, 95%CI: 5-17%) were positive for MAP infection based on IS900 nested PCR. The prevalence of positive milk samples in the three districts of Fars province was different ranging from 8.6% to 23% which was not statistically significant (P=0.19). It is recommended to conduct further epidemiologic studies to determine cow-level prevalence and risk factors for infection, and to evaluate the economic consequences of the MAP infection in the region.     

Predictive ability of models for calving difficulty in US Holsteins

The performance of alternative threshold models for analyzing calving difficulty (CD) in Holstein cows was evaluated in terms of predictive ability. Four models were considered, with CD classified into either three or four categories and analysed either as a single trait or jointly with gestation length (GL). The data contained GL and CD records from 90 393 primiparous cows, sired by 1122 bulls and distributed over 935 herd-calving year classes.
Predictive ability of each model was evaluated using four criteria: mean squared error of the difference between observed and predicted CD scores; a Kullback-Leibler divergence measure between the observed and predicted distributions of CD scores; Pearson's correlation between observed and predicted CD scores and ability to correctly classify bulls as above or below average for incidence of CD.
In general, the four models had similar predictive abilities. The joint analysis of CD with GL produced little, if any, improvement in predictive ability over univariate models. In light of the small difference in predictive ability between models treating CD with three or four categories and considering that a greater number of categories can provide more information, analysis of CD classified into four categories seems warranted.     

Study of reproductive performance and related factors in four dairy herds in Fars province (southern Iran) by Cox proportional-hazard model

Our objective was to characterize the current reproductive performance and factors which may be related to it in the Fars province dairy herds in southern Iran. We collected retrospective data from four commercial herds in the region. All 256 cows with history of calving between 21 March 2004 and 20 March 2005 were followed until subsequent pregnancy, culling or death. Effects of risk factors on days open were investigated in a Cox proportional-hazards model. The overall median calving interval, dry period and days open were 388, 68, and 120 days, respectively. First-service conception risk and overall-service conception risk were 45 and 42%, respectively. Average numbers of insemination per pregnant and all cows were 2 and 2.1, respectively. Cows without incidence of any disorder during the lactation (but before conception, and including metabolic disorders) had 2.1-times greater hazard of conception than cows with incidence of disease. No significant association between calving interval, dry period, parity of dam, and sex and weight of calves with days open was observed.     

Relationship between calving difficulty and fertility traits in first‐parity Iranian Holsteins under standard and recursive models

The main objective of this study was to estimate the genetic and phenotypic relationships between calving difficulty (CD) and fertility traits, including success at first service (SF), number of inseminations to conception (INS), interval from calving to first service (CTFS), interval between first and last service (IFL) and days open (DO), in first‐parity Iranian Holsteins under standard (SMMs) and recursive (RMMs) mixed models. The data analysed in this paper included 29 950 records on CD and fertility traits, collected in the time period from 1995 to 2014 by the Animal Breeding and Improvement Center of Iran. Under all observed SMMs and RMMs, five bivariate sire‐maternal grandsire models (ten bivariate analyses in total) were used for the analyses. Recursive models were applied with a view to consider that CD influences the fertility traits in the subsequent reproductive cycle and the genetic determination of CD and fertility traits by fitting CD as covariate for any of the fertility traits studied. The existence of such cause‐and‐effect is considered in RMMs but not in SMMs. Our results implied a statistically non‐zero magnitude of the causal relationships between CD and all the fertility traits studied, with the former influencing the latter. The causal effects of CD on SF (on the observed scale, %), INS, CTFS, IFL and DO were ?2.23%, 0.10 services, 1.93 days, 3.76 days and 5.61 days, respectively. Direct genetic correlations between CD and the fertility traits under both models were not statistically different from zero (95% HPD interval included zero), except for the correlation between CD and CTFS, which were 0.197 and 0.134 under SMM and RMM, respectively, indicating that genes associated with difficult births also increase intervals between calving and the first insemination afterwards. Comparison of both models by the deviance information criterion (DIC) demonstrated the plausibility of RMMs over SMMs.     

An analysis of age and body weight at first calving for Holsteins in the United States

In a national survey of US dairy producers, only 2.7 ± 0.5% of Holstein dairy operations reported achieving recommended target ranges of age ≤ 24 months and body weight (BW) ≥ 550 kg at first calving. Allowing for wider target ranges, still only 14.6 ± 1.3% of Holstein dairy operations reported achieving age ≤ 25 months and BW ≥ 544.3 kg at first calving. Ages of individual first-calf heifers observed at calving were heavily skewed toward older individuals. Dairy producers reported an average age at first calving that was 1.3 months lower than the mean and 1.0 months lower than median age of first-calf heifers' observed calving on the operations. Stepwise logistic regression was used to identify the herd characteristics associated with producers reporting first calvings within the wider age and BW target ranges for Holsteins. Rolling herd average milk production ≥ 7711 kg/yr, using a computer for recordkeeping, and not tying preweaned heifers in a barn with cows, were associated with achieving the target BW and age at first calving.     

Studies on correlations among parasitaemia and some hemolytic indices in two tropical diseases (theileriosis and anaplasmosis) in Fars province of Iran

This study was carried out in two observational clinical studies. Study 1 comprised 50 adult crossbred cattle naturally infected by Theileria annulata. Infected animals were divided into 4 subgroups with different parasitaemia (<1%, 1–3%, 3–5% and >5%). Study 2 comprised 20 adult crossbred cattle naturally infected by Anaplasma marginale. Infected animals were divided into 3 subgroups with different parasitaemia (<10%, 10–20% and 20–30%). In study 1, a significant negative correlation (P < 0.001) was observed between parasitaemia and superoxide dismutase (SOD). Positive correlations (P < 0.001) were observed between parasitaemia and lactate dehydrogenase (LDH) and mean corpuscular fragility (MCF). In study 2 positive correlations (P < 0.05) were observed among parasitaemia and MCF and LDH activity. SOD activity had a negative correlation with parasitaemia in cattle with parasitaemia lower than 10% but no significant correlation (P > 0.05) was observed between SOD activity and parasitaemia in cattle with 10–20 and 20–30% parasitaemia. In comparison of both studies we came to the conclusion that in theileriosis as the severity of disease increased the anaemia, MCF and LDH activity increased and SOD activity decreased at any parasitaemia, but in anaplasmosis the anaemia, MCF and LDH activity increased at any parasitaemia but SOD activity decreased only in early but not in advanced stages of disease.     

Genetic parameters for stayability, stayability at calving, and stayability at weaning to specified ages for Hereford cows

Genetic parameters for stayability to six ages (ST1, . . ., ST6), for five measures of stayability to calving (SC2, . . ., SC6), and for five measures of stayability to weaning (SW2, . . ., SW6), were estimated using records of 2,019 Hereford cows collected from 1964 to 1979 from a selection experiment with a control line and three lines selected for weaning weight, yearling weight, and an index of yearling weight and muscle score. The model included birth year of the cow as a fixed effect and the cow's sire as a random effect. Analyses were performed with 1) a generalized linear mixed model for binary data using a probit link with a penalized quasi-likelihood function, and 2) with a linear mixed model using REML. Genetic trends were estimated by regressing weighted means of estimated transmitting abilities (ETA) of sires by birth year of their daughters on birth year. Environmental trends were estimated by regressing solutions for year of birth on birth year. Estimates of heritability (SE) for ST were between 0.09 (0.08) and 0.30 (0.14) for threshold model and between 0.05 (0.04) and 0.19 (0.09) for linear model. Estimates of heritability from linear model analyses transformed to an underlying normal scale were between 0.09 and 0.35. Estimates of heritability (SE) for SC were between 0.29 (0.10) and 0.39 (0.11) and between 0.18 (0.09) and 0.25 (0.08) with threshold and linear models. Estimates of heritability transformed to an underlying normal scale were between 0.30 and 0.40. Estimates of heritability (SE) for SW were between 0.21 (0.14) and 0.47 (0.19) and between 0.12 (0.08) and 0.26 (0.12) with threshold and linear models, respectively. Estimates of heritability transformed to an underlying normal scale were between 0.21 and 0.50. Estimates of genetic and environmental trends for all lines were nearly zero for all traits. Correlations between ETA of sires for stayability to specific ages, for stayability to calving, and for stayability to weaning with threshold and linear models ranged from 0.09 to 0.82, from 0.68 to 0.90, and from 0.67 to 0.87, respectively. Selection for stayability would be possible in a breeding program and could be relatively effective as a result of the moderate estimates of heritability, which would allow selection of sires whose daughters are more likely to remain longer in the herd. Selection for weaning and yearling weights resulted in little correlated response for any of the measures of stayability.     

Molecular survey of <Emphasis Type="Italic">Toxoplasma</Emphasis> infection in sheep and goat from Fars province,Southern Iran

Toxoplasmosis is a widespread zoonotic disease that causes significant morbidity and mortality in human fetus and in immunocompromised patients. Moreover, it becomes a major cause of abortion in sheep and goats. Since consumption of meat of infected lamb and goat is considered as the main sources of human infection in Iran, this study was undertaken to determine the prevalence of Toxoplasma infection in edible tissues of sheep and goats in Shiraz in 2008. Samples of brain, tongue, liver, and muscles of neck, intercostals, and femoral were taken from 56 sheep and 22 goats and tested by PCR. The total prevalence of Toxoplasma infection among animals was found to be 33.3%. Five out of 22 goats (22.7%) and 21 out of 56 sheep (37.5%) were infected by Toxoplasma. Differences between the prevalence rate of infection among females (nine out of 14 = 46%) and males animals (12 out of 45 = 29.5%) was significant (P = 0.013). Furthermore, a positive correlation was found between the age of animals and the rate of infection; animals greater than 2 years old showed a higher rate of infection (47%) in comparison with those less than 2 years old (25%, P = 0.04). The highest infected tissue was tongue (21.8%) followed by brain (19.2%) and femoral and intercostal muscles (17.9%). This study demonstrated a high level of Toxoplasma infection in slaughtered animals in Shiraz and these should be considered as the main sources of infection for human population in the region.     

The distribution pattern of Sarcocystis species,their transmission and pathogenesis in sheep in Fars Province of Iran

Of 1362 sheep examined during two years in Fars Province of Iran, 786 (57.7%) were positive for Sarcocystis spp. The prevalence was significantly higher (p<0.05) in animals owned by nomadic Assyrians (67.95%) than in those owned by local people (41.86%). More of the animals above 2 years age were infected (69.98%) than young ones (30.02%). Females had a higher prevalence of infection (61.07%) than males (38.93%) but most of the males were younger. There was no variation in the infection rate during spring, summer or autumn, but it was low in winter. The species observed were Sarcocystis gigantea, predominantly in oesophagus, S. medusiformis, mainly in diaphragm, S. tenella in the oesophagus, diaphragm, tongue and heart, and S. arieticanis in the oesophagus, tongue and occasionally in the diaphragm. In transmission studies, the prepatent period for S. gigantea and S. medusiformis and for the two microscopic species was 11–13, 10 and 8–12 days, respectively. The infection could not be transmitted to hamsters and guinea-pigs. The macroscopic species were almost non-pathogenic but were responsible for economic losses because of rejection of carcases or parts thereof at slaughter. The microscopic species caused tissue damage to the affected organs, resulting in haemorrhages, mononuclear infiltration and necrotic changes.Abbreviations DPI days post infection     

Pituitary concentrations of gonadotropins and receptors for GnRH in suckled beef cows at various intervals after calving

Mature beef cows were slaughtered at 5 (n = 6), 10 (n = 6), 20 (n = 6) or 30 (n = 5) d after calving to identify endocrine events that may affect the duration of postpartum anestrus. Additional cows (n = 6) were slaughtered 12 to 14 d after their first postpartum estrus (luteal phase cows). Anterior pituitary concentrations of luteinizing hormone (LH) were low at d 5 (383 +/- 69 micrograms/g), averaged 445 +/- 103 and 682 +/- 207 micrograms/g at d 10 and 20, respectively, and were elevated (P less than .05) by d 30 (1,097 +/- 174 micrograms) to a concentration similar to luteal phase cows (1,208 +/- 148 micrograms/g). Concentrations of follicle-stimulating hormone (FSH) averaged 12.4 +/- 1.1, 9.6 +/- 2, 8.6 +/- 1.8 and 7.4 +/- 3.3 mg/g at d 5, 10, 20 and 30, respectively. Affinity (1.6 +/- .2 X 10(9) M-1) of anterior pituitary receptors for the GnRH (gonadotropin-releasing hormone) analog (DAla6; des-Gly10, [D-Ala6]-LH-RH ethylamide) and weights (2.1 +/- .1 g) of the anterior pituitaries did not differ among groups (P greater than .05). Number of receptors for GnRH averaged 37 +/- 7, 39 +/- 9, 25 +/- 5 and 23 +/- 5 X 10(-14) M/mg protein at d 5, 10, 20 and 30, respectively. Anterior pituitaries from luteal phase cows contained 22 +/- 2 X 10(-14) M/mg protein of receptors for GnRH.(ABSTRACT TRUNCATED AT 250 WORDS)     

Natural markings and their use in determining calving intervals in right whales off South Africa

Since 1979, 245 right whales (excluding calves) have been individually identified in aerial photographs taken annually on the South African coast, using variations in dorsal pigmentation and callosity patterns. White or grey blazes (or both) occurred dorsally in 16,7% of individuals, one form of which (partial albinism) occurred in 3,6% of the calves born but may be sex linked. In 19 animals carrying dorsal marks that were resighted two to seven years later, changes in the appearance of the callosities were noted in 95% of individuals, 58% showing pronounced changes. Definite matches between years were made for 139 cows with calves. The average per capita calving interval, adjusted for incomplete spatial and temporal coverage, was 3,183 ± 0,091 (SD) years, or a calf production rate of 0,314 ± 0,009 (SD) per adult female per year. From a simple model it is shown that rates of population increase as high as that observed (6–7%) can only be maintained with a calf production rate of this order if the age at first parturition is relatively low and/or the adult survival rate high.     

Prevalence and risk factors for subclinical coccidiosis in broiler chicken farms in Mazandaran province,Iran

Coccidiosis is a disease of almost universal importance in Poultry production. The subclinical form of coccidiosis has most significant economic impact due to impaired growth rate and feed conversion. Some factors such as: age, size of flock, season, etc., may effect on severity of this disease. In this study, the relationships between some major risk factors and prevalence of subclinical coccidiosis were investigated. This study was done in 120 broiler farms in five different cities of Mazandaran province, north of Iran. Five chicks (3–8 weeks of ages) were taken randomly from every 120 farms and post-mortem and parasitological examinations were performed. Five Eimeria spp. were recognized: Eimeria tenella, Eimeria maxima, Eimeria acervulina, Eimeria brunetti, and Eimeria necatrix. The prevalence rate of subclinical coccidiosis among them is 75% (90 farms out of 120). E. acervulina was the most prevalent species (65.5%) followed by E. maxima (17.7%), E. tenella (15.5%), E. brunetti (10%), and E. necatrix (5.5%). According to what the results approve, the occurrence of subclinical coccidiosis is significantly related to the age and size of flock, whereas the other factors such as the season of year, industrial strains, chicken’s keeping system, and anticoccidial drugs do not affect this phenomenon remarkably.     

Some observations on sheep sarcoptic mange in Tehran province,Iran

Sarcoptes scabiei infestation was diagnosed in 278 sheep from 12 fatling flocks. The sheep presented crusted skin lesions initially appear on the lips or nostrils, the lesion on nostrils also extend towards around the eyes, the supraorbital fossae and in some cases over entire face. The infested male lambs by mating behavior in fatling flocks caused transmitting the infection to fat tail area and scrutum. Histopathological study of lesions demonstrated marked acanthosis, hyperkeratosis, parakeratosis. Tunnels could be observed in the hyperkeratotic stratum corneum and mite segments were located mainly in the stratum corneum and also in the stratum granulosum. Attempts to eliminate S. scabiei var. ovis were made in 3 naturally infested sheep herds, by two dippings with two weeks interval with Amitraz, Cypermetrin and Prompetamphos. The results of this study indicate that acaricidal treatment of S. scabiei var. ovis in 3 naturally infested herds was successful, but a few cases of reinfestation were found in each treated group.