Resynchronization of estrus in beef cattle: ovarian function, estrus and fertility following progestin treatment and treatments to synchronize ovarian follicular development and estrus

The objective was to optimize rebreeding of nonpregnant, previously inseminated beef cattle. In Experiment 1, 43 cows received a used intravaginal progesterone-releasing insert (IVPRI; Days 0-7) 12.3 d after ovulation and received concurrently no treatment, 100 microg gonadotropin releasing hormone (GnRH), 1 mg estradiol cypionate (ECP), or 150 mg progesterone. Emergence of a new ovarian follicular wave was most synchronous (P < 0.0001) in the GnRH group. In Experiment 2, 675 heifers were given GnRH or no treatment on Day 0, fed melengestrol acetate (MGA; 0.5 mg/head/d) from Days 0-5 (Day 0 = 13-14 d after timed insemination; TAI), given 0.5 mg ECP or nothing on Day 7, and reinseminated 6-12 h after onset of estrus. Estrus was more synchronous (P < 0.05) in heifers given GnRH versus no treatment on Day 0. In Experiment 3, 317 TAI heifers were resynchronized with either MGA or a used IVPRI with or without ECP on Day 7; estrus was more synchronous (P < 0.05) and pregnancy rates were higher (54.1% versus 39.2%, P < 0.05) in heifers given a used IVPRI than those fed MGA. For resynchronization of heifers, pregnancy rates were not significantly improved with GnRH treatment, but were higher with a used IVPRI than with MGA.     

Detection of Mycobacterium avium ssp. paratuberculosis in ileocaecal lymph nodes collected from elderly slaughter cows using a semi-nested IS900 polymerase chain reaction

The aim of this study was to investigate the occurrence of subclinical Mycobacterium avium spp. paratuberculosis (MAP) infections at slaughter by testing ileocaecal lymph nodes with a semi-nested IS900 PCR. Tissue samples were available within the framework of a parallel study investigating BSE-susceptibility factors in members of BSE-cohorts in the German Federal State of Lower Saxony. Ileocaecal lymph nodes were collected over a 2-year sampling period from 99 slaughter cattle of a mean age of 6.5 years (5.5-7.5 years). A recently developed IS900 semi-nested polymerase chain reaction (snPCR) assay offering a sensitivity of 1 genome equivalent was used for the detection of MAP-DNA. Based on this snPCR, 17 out of the 99 samples gave positive results, indicating a MAP occurrence of 17.17% in the random sample. All PCR products were sequenced for screening of polymorphisms. Nucleotide homologies of 98.5-100% were found with respect to the MAP K10 reference sequence IS900 (GenBank: AE16958). PCR analysis of ileocaecal lymph nodes collected from slaughter cattle proved to be a suitable technique to determine MAP occurrence in the local cattle population.     

Spatial distribution of Aspergillus flavus and its toxigenic strains on commercial cottonseed from south Texas and its relationship to aflatoxin contamination

The structure of Aspergillus flavus communities associated with south Texas cottonseed was determined by analysing samples from 178 truckloads of commercial cottonseed from 35 gins, extending from Fort Bend County in the north to the Rio Grande Valley in the south, from September 1999 to October 2001. The number of colony-forming units (CFU) of A. flavus on the cottonseed, and the percentage of S strain (%S) were both correlated with aflatoxin contamination of cottonseed. The number of CFU differed between both regions and seasons, while %S differed only between regions. Comparison of maps of CFU and %S revealed that CFU shows a higher variation across years, while %S shows higher spatial variation. The Rio Grande Valley had significantly lower CFU and %S strain than the Coastal Bend and Upper Coast regions. Cottonseed produced in 1999 had significantly more A. flavus than that produced in either 2000 or 2001. Identification of factors dictating geographical variation in S-strain incidence may provide insights that will lead to improved aflatoxin management.     

The breed prevalence of dog erythrocyte antigen 1.1 in the Onderstepoort area of South Africa and its significance in selection of canine blood donors

The blood group antigen Dog Erythrocyte Antigen (DEA) 1.1 is clinically the most important canine blood group as DEA 1.1 antibodies are capable of causing acute haemolytic, potentially life-threatening transfusion reactions. Dogs do not have naturally occurring antibodies to DEA 1.1 but are rapidly sensitised by the first incompatible transfusion. The prevalence of DEA 1.1 in the general dog population is estimated at 42-46%. Canine blood donors registered with the Onderstepoort Animal Blood Bank (n = 93) as well as potential donors (n = 140) were typed for DEA 1.1 using a monoclonal antibody card kit. All dogs came from the Onderstepoort area, near Pretoria, Gauteng province, South Africa. Overall prevalence of DEA 1.1 was 47%. Prevalence was 47% in purebred dogs and 48% in mongrels. Distinct breed differences were noted with less than 20% of German shepherd dogs and Boxers and greater than 75% of Rottweilers, Great Danes, St Bernards and Dalmations testing DEA 1.1 positive. Knowledge of local breed differences will increase effectiveness of blood donor recruitment.     

Influence of trenbolone acetate combined with estradiol-17 beta on growth performance, body characteristics, and chemical composition of goat kids fed milk and slaughtered at different ages.

The effects of anabolic agents (5 mg of estradiol-17 beta + 30 mg of trenbolone acetate) on body characteristics and chemical composition of gain were studied in 58 intact male goat kids fed milk replacer. Four kids were slaughtered at 7 d of age to constitute the initial group. The other kids were allotted in a 2 x 3 factorial arrangement with slaughter age (41, 49, and 56 d of age) and treatment (control and implanted at 21 d old) as factors. Energy intake decreased during the first 4 wk after treatment; implanted kids had the same ADG as controls but a better energy efficiency (P < .05). During the last week of the trial, energy intake was the same; treated kids tended (P < .10) to have a higher empty body gain (EBG). Anabolic agents increased carcass (P < .10) and hide proportions (P < .01) in empty BW and in EBG for all groups (except for carcass at 56 d old). Anabolic agents reduced the contribution of adipose tissues (P < .05), empty digestive tract (P < .05), and other organs (P < .01) to EBG. At all slaughter ages, the chemical composition of carcass and hide wet tissues, all dissectible adipose tissues, and EBG were altered by treatment. In these tissues (except for mesenteric fat tissue), water content increased and lipid content decreased (P < .05), but these effects diminished with age. Expressed on a DM basis, the CP content of the treated carcasses was increased in all groups (P < .05). Implanting high doses of steroids altered nutrient partitioning, which reduced fat and increased water and protein in the body.     

Describing the growth and molt of modern domestic turkey (Meleagris gallopavo) primary wing feathers

The use of feathers as noninvasive physiological measurements of biomarkers in poultry research is expanding. Feather molting patterns and growth rates, however, are not well described in domestic poultry. These parameters could influence the measurement of these biomarkers. Therefore, the objective of this study was to describe the juvenile primary feather molting patterns and feather growth rates for domestic turkeys. The 10 primary wing feathers of 48 female turkeys were measured weekly from week 1 (0 d of age) to week 20. Feathers were manually measured, and the presence or absence of each primary feather was recorded weekly. Generalized linear mixed models were used to investigate if feather growth differed between the primary feathers. The molting of the juvenile primary feathers followed a typical descending pattern starting with P1 (5 wk of age), while P9 and P10 had not molted by the end of the study (20 wk of age). The average feather growth rate was 2.4 cm/wk, although there was a significant difference between the 10 primary feathers (P < 0.0001, 2.1 to 2.8 cm/wk). Over time, feather growth followed a pattern where the growth rate reaches a peak and then declines until the feather is molted. The results of this study provide a critical update of patterns of molting and feather growth in primary wing feathers of modern turkeys. This can have implications for the interpretation of physiological biomarkers, such as the longitudinal deposition of corticosterone, in the feathers of domestic turkeys.     

Establishment of trees on mixtures of pulverized fuel ash and Gypsum. Part II: Nutrition and trace elements

Nutrients and trace elements were determined in the foliage of nine tree species grown in mixtures of pulverized fuel ash (PFA) and gypsum. No serious macronutrient deficiencies were observed. Treatments with PFA consistently increased foliar levels of boron, potassium and molybdenum, and the poor performance of some tree species in pure PFA was attributed to boron toxicity. Gypsum hindered the uptake of boron when mixed with PFA, however, and co-disposal of the two wastes could be used to minimize problems associated with boron toxicity.