Does transport of water to roots limit water uptake of field crops?

The question was examined under which conditions the water extraction rate of plant roots in the field can be limited by water transport to the roots. For this purpose we used a numerical solution of the single root model. Scenario calculations were carried out in order to investigate the general model behaviour. A sensitivity analysis showed that initial volumetric water content and root length density are of greater importance than root diameter in determining the maximum water transport rate to the roots. Data from a field experiment were taken, describing root length density, volumetric water content and water uptake rates under oats (Avena saliva L.) and faba beans (Vicia faba L.) as model input parameters. With this data the model calculated the water content difference between the bulk soil and the root surface which is necessary to induce a water flow to the roots matching the observed water uptake rate. Root length densities below the grain legume crop faba beans are one order of magnitude lower compared to that of the cereal crop oats. The therefore higher specific water influx rates of faba beans roots resulted in a higher decrease in water content near the root surface. However, water uptake by faba beans was controlled by the water flow towards the roots probably only in deeper soil layers with very low root length density. For the given conditions no transport limitation of water uptake was calculated, when rooting densities were higher than about 0.1 cm.cm^?3.     

Effects of Sarcocystis miescheriana infection on carcass quality and on the water-binding capacity of the meat of halothane-tested fattening pigs

Ten halothane-positive pigs (stress sensitive, group A) and ten halothane-negative pigs (stress insensitive, Group C) with a mean body weight of 36 kg were each inoculated orally with 50,000 sporocysts of Sarcocystis miescheriana. Twelve halthane-positive pigs (Group B) and ten halothane-negative pigs (Group D) served as non-infected controls. Thirteen weeks post infection (p.i.) the lean: fat ratios of the pigs of the infected groups A and C were lower (A, 1:0.41 +/- 0.09; C, 1:0.50 +/- 0.10) than those of the pigs of the non-infected groups B and D (B, 1:0.50 +/- 0.08; D, 1:0.55 +/- 0.08). The back-fat thickness, the fat thickness 'A' and the fat thickness 'B' were thinner in infected pigs than in non-infected pigs. The difference in Lendenst?rkespeckquotient (Loin Fat Thickness Quotient) (LSQ) between infected and non-infected pigs was not statistically significant. The values of the water-holding capacity were lower in infected pigs than in non-infected pigs, the difference being statistically significant only in the halothane-negative groups (C, 0.45 +/- 0.02; D, 0.48 +/- 0.04). The water-absorbing capacity was significantly higher in the infected groups (A, 5.92 +/- 3.99%; B, 2.26 +/- 1.08%; C, 8.96 +/- 2.90%; D, 4.97 +/- 2.51%). In conclusion, it can be said that there was a slight tendency towards a better carcass quality and a better water-binding capacity in infected pigs, although this was combined with reduced growth rates.     

Meat composition and palatability of Holstein and beef steers as influenced by forage type and protein source.

This experiment determined meat composition and palatability changes resulting from feeding Holstein (HOL) and crossbred beef (XB) steers diets containing corn silage (CS) or alfalfa haylage (AH) (forage type) and soybean meal (SM) or fish meal (FM) (protein source). Fifty-nine steers (30 HOL and 29 XB) were randomly assigned to diet combinations for a 2 x 2 x 2 (breed x forage x protein) factorial arrangement. Steers were fed to a fat-constant end point (fat depth over the longissimus muscle measured by ultrasound: 1.0 cm XB, .6 cm HOL). Proximate and fatty acid analysis and sensory evaluation were conducted on a rib eye roast and steaks, respectively, removed from the left side of each carcass at ribs 9 to 12. Proximate analysis of the longissimus muscle showed no significant difference (P greater than .05) in moisture, protein, or fat content due to breed, forage, or protein treatment. Forage type had no significant effect (P greater than .05) on amount of individual fatty acids found in longissimus muscle. However, total polyunsaturated fatty acids were higher (P greater than .05) for AH than for CS-fed animals. Longissimus muscle from steers fed FM had higher palmitoleic and lower stearic acid contents (both P less than .05) than longissimus muscle from animals fed SM. Muscle from HOL had higher palmitoleic and lower stearic acid contents than that from XB steers (both P less than .05). There was no significant interaction (P greater than .05) of breed with either diet treatment for individual fatty acid contents.(ABSTRACT TRUNCATED AT 250 WORDS)     

Body and claw measurements and pressure distribution under the claws in calves of different cattle breeds

In 58 female calves of the three breeds German Holstein (GH), German Brown (GB) and German Red (GR) the body weight and height were determined at the age of 79 to 188 days. At the right front limb and the left hind limb the following claw measurements were taken: dorsal border length, diagonal length, heel length and height, angle of the dorsal border and hardness of the claw horn. Furthermore, the punctual pressure under the medial and the lateral claw of the right front limb and the left hind limb were determined using an electronic measuring system. The GH calves weighing 136.8 kg were heavier than GB, which was the tallest breed with 106.2 cm height at the sacral bone. GR calves were the smallest (99.1 cm) and weighed 121.1 kg. The length of the diagonal and the angle of the dorsal border were smaller at the hind limb of all breeds which resulted in a smaller area of ground surface for the claw of this limb. The GR calves had the longest and flattest claws. The GB showed the highest pressures per cm2 at the front limb with 25.6 N/cm2 under both claws as well as at the hind limb with 26.7 N/cm2. The AR had the smallest pressure load with 20.8 N/cm2 at the front limb and 20.2 N/cm2 at the hind limb. The animals showed a larger relative weight load and area of ground surface on the medial claws of the front and hind limbs than on the lateral claws. The highest pressures were found underneath the rear part of the medial claw in all breeds. GB calves showed the highest average pressures (33.3 N/cm2 at the front limb) while GR calves had the lowest (26.3 N/cm2 at the hind limb). GR calves had the highest claw hardness at all measuring positions.     

Genotype effects of milk protein polymorphisms on milk production in East Friesian dairy sheep

The frequencies of milk protein variants alphas1-casein, alphas2-casein, beta-casein and beta-lactoglobulin were determined in 182 milk sheep from 7 flocks in Lower Saxony and Saxony. The genotype effects of these polymorphic milk protein variants on milk performance traits were estimated for 173 ewes using a test day model with fixed regression.The model included the fixed effects of colour variant of the breed, region, lambing season, lambing year, lactation number and number of lambs born. The herd and animal effect were treated as random and the days in milk as linear and non-linear covariates. The milk protein variants of alphas1-casein and beta-casein showed a significant relationship to protein content and the variants of beta-casein to milk fat content. Milk fat yield was significantly associated with the milk protein variants of alphas2-casein, whereas the other milk performance traits were not significantly correlated.     

Genetic-statistical analysis of environmental and genetic influences on the outcome of the juvenile and breeding performance tests for behaviour traits in Hovawart dogs

The objective of the present study was to evaluate the importance of genetic and environmental sources of variation for results of behaviour tests recorded at juvenile and breeding performance tests in the Hovawart dog. For these analyses behaviour test results of 1882 (juvenile evaluation), respectively 929 dogs (breeding performance test) born in 1995 to 2000 had been used. Variance component estimation was performed for the traits appearance, play instinct, hunting affinity, group of people, shoot, acoustical and optical influences and temperament using multivariate linear animal models and Residual Maximum Likelihood (REML). The models included test-year-season, sex, litter size, age and inbreeding coefficient of the animal as fixed effects. Additive genetic effects of the animal, permanent environmental effect of the litter and the effect of the kennel were considered as random factors.The sex of the dog was significant for appearance, play instinct, hunting affinity, acoustical and optical influences of juvenile evaluation and for the traits temperament, play instinct, hunting affinity, acoustical and one of the optical influences of breeding performance test.The age of the dog at test significantly influenced the traits play instinct, hunting affinity and acoustical influences of juvenile evaluation and optical influences and hunting affinity of breeding performance test. All traits with exception of hunting affinity and group of people were significantly affected by the test-year-season. The inbreeding coefficient was significant for appearance of juvenile evaluation and play affinity of breeding performance test. The effect litter size did not influence any of the traits significantly.The estimated heritabilities for the behaviour traits of juvenile and breeding performance test ranged from h2 = 0.01 to h2 = 0.13, respectively h2 = 0.01 to h2 = 0.14, with standard errors of up to 0.03. The additive genetic correlations between most of the traits were moderately to highly positive (r(g) = 0.20 to r(g) = 1.0, respectively r(g) = 0.29 to r(g) = 1.0). Negative additive genetic correlations were only found for a few traits of juvenile (r(g) = -0.02 to r(g) = -0.58) and breeding performance test (r(g) = -0.28 to r(g) = -0.83). Progress in breeding for the behaviour traits investigated here may only be meaningful when information from all relatives is used in an animal model instead of selection based on the phenotype of the single animal.     

Variable number of tandem aminoacid repeats in adhesion-related CDS products in Mycoplasma hyopneumoniae strains

The Mycoplasma hyopneumoniae genome contains at least 22 regions with a variable number of tandem nucleotide repeats (VNTRs) within coding DNA sequences (CDSs). In this work, the VNTR-containing CDSs were analysed in order to evaluate their degree of variation, possible correlations with antigenic properties, and their potential to be used as a basis for a strain typing PCR assay. We have analysed the VNTRs in five M. hyopneumoniae strains (J, 7448, 7422, PMS, and 232), based on published genomic sequences and on amplified and sequenced DNA segments. These VNTRs are distributed among 12 genes, most of which encode putative surface proteins, including known adhesins. The number of repeat units in any of the VNTRs is highly variable among the analysed strains, but they are, without exception, translationally in frame, and, therefore, code for a variable number of aminoacid repeats (VNTARs). These VNTARs determine putative structural, physicochemical and antigenic variations in the corresponding proteins, with potential implications for aspects associated to M. hyopneumoniae pathogenicity, such as cell adhesion and interactions with the host immune system. Considering that the characterized VNTARs are relatively stable, at least in vitro, and their sizes are strain-specific, we have developed a VNTR-based PCR assay for M. hyopneumoniae strain identification, useful for enzootic pneumonia (EP) diagnosis, strain typing, and distinction of circulating field isolates from vaccine strains in animals vaccinated against EP.     

Biocatalytic production of dihydrocoumarin from coumarin by Saccharomyces cerevisiae

Natural dihydrocoumarin, which is of great interest in the flavor industry, was biotechnologically produced from pure coumarin or tonka bean meal with Pseudomonas orientalis, Bacillus cereus, and various Saccharomyces cerevisiae strains. Coumarin was shown to be converted to melilotic acid, which yielded dihydrocoumarin upon distillation during purification. About 1.0 g/L product was obtained from 25 g/L tonka beans with S. cerevisiae within 147 h. This dihydrocoumarin thus fulfills all of the criteria of a natural raw material and can be used as a natural flavoring in accordance with U.S. and European Union regulations.     

A serial cross-sectional study of the prevalence of rabbit haemorrhagic disease on three farms in the lower North Island of New Zealand

AIM: To estimate over a 3-year period following the first release of rabbit haemorrhagic disease virus (RHDV) the prevalence of rabbit haemorrhagic disease (RHD) and the abundance of rabbits (Oryctolagus cuniculus) in an area that historically had low rabbit densities.

METHODS: Three farms grazing predominantly sheep and beef cattle, located close together and with low initial rabbit densities, were selected for study. RHDV had been deliberately released on all farms in December 1997. Farms were visited 2–3 times per year between June 1998 and April 2001. At each visit, rabbits were shot with the aid of spotlights at night and blood samples were collected for detection of RHDV antibodies. Rabbit carcasses were necropsied and the age of the animals was determined. Rabbit abundance on each property was measured throughout the study using spotlight night counts. Logistic regression was used to identify factors associated with the risk of carcasses being seropositive for RHDV.

RESULTS: Rabbit density differed initially between farms (8.2, 9.9, 2.3 rabbits per spotlight km in June 1998), and declined on all three properties over time (1.2, 2.4, 1.1 rabbits per spotlight km in November 2000). Highest antibody titres to RHDV were initially evident on the farm on which rabbits were most abundant. The average prevalence of seropositive rabbits overall was 21% (95% CI=15–28%). Female rabbits tended to be less likely to be seropositive for RHDV than males (OR=0.47; 95% CI=0.21–1.02). The odds of becoming seropositive were reduced for rabbits born in the breeding season of 1999–2000 (OR=0.17; 95% CI=0.05–0.64).

CONCLUSIONS: The temporal pattern of outbreaks measured by peaks of seroprevalence differed between closely-spaced farms when they had different rabbit densities, but were similar when rabbit densities were similar. Microclimate and vegetation influencing abundance of insect vectors for RHDV and intrinsic population-related factors like rabbit breeding behaviour are also likely to be involved in local patterns of spread.