Effects of the ruminal comminution rate and microbial contamination of particles on accuracy of in situ estimates of ruminal degradability and intestinal digestibility of feedstuffs

Effects of considering the comminution rate (k_c) and the correction of microbial contamination (using ¹⁵N techniques) of particles in the rumen on estimates of ruminally undegraded fractions and their intestinal digestibility were examined generating composite samples (from rumen‐incubated residues) representative of the undegraded feed rumen outflow. The study used sunflower meal (SFM) and Italian ryegrass hay (RGH) and three rumen and duodenum cannulated wethers fed with a 40:60 RGH to concentrate diet (75 g DM/kgBW^0.75). Transit studies up to the duodenum with Yb‐SFM and Eu‐RGH marked samples showed higher k_c values (/h) in SFM than in RGH (0.577 vs. 0.0892, p = 0.034), whereas similar values occurred for the rumen passage rate (k_p). Estimates of ruminally undegraded and intestinal digestibility of all tested fractions decreased when k_c was considered and also applying microbial correction. Thus, microbial uncorrected k_p‐based proportions of intestinal digested undegraded crude protein overestimated those corrected and k_c?k_p‐based by 39% in SFM (0.146 vs. 0.105) and 761% in RGH (0.373 vs. 0.0433). Results show that both k_c and microbial contamination correction should be considered to obtain accurate in situ estimates in grasses, whereas in protein concentrates not considering k_c is an important source of error.     

The effect of aging of milk samples on the accuracy of infrared analysis of milk composition]

The effect of a decrease (and/or fermentation) in the lactose content during milk storage under different conditions was investigated on the accuracy of the results obtained on a Milko-Scan apparatus to contribute to the present knowledge of this problem. The results were in agreement with some results cited in the literature. These wavelengths are used for infrared spectrophotometry on the above apparatus: for fat 3.48 microns, for proteins 6.46 microns and for lactose 9.60 microns. Bulk milk samples used for the tests were untreated or treated with potassium dichromate, bronopol, sodium azide and Milkofix at the temperatures of storage in darkness 20 degrees C and 4 degrees C. The differences against the reference values (measured on the first day) were determined and evaluated in milk composition and characteristics as arising during milk storage. These differences were used in form of either cumulative means of differences (Figs. 1 to 5) or individual differences (Fig. 8). In the first part significant correlation coefficients (P less than 0.001) were calculated for the relationship between the variations of lactose content and the fat and protein contents: r = -0.59 and/or -0.73 (Figs. 6 and 7). This suggests that the decrease in the lactose content by 0.10% recorded by the infrared analysis and caused by lactose decomposition is accompanied by a "seeming" increase in the fat and protein content by about 0.04%. In the second part the correlation coefficients for the fat and protein contents r = -0.96 and -0.96 (P less than 0.001; Figs. 9 and 10; Tab. II) were calculated on the basis of an observation of the lactose decrease in an untreated milk sample (20 degrees C for 28 hours). These coefficients are somewhat different from the preceding ones; this is due to the lower homogeneity of the first set where the milk samples were treated in a different way, but the coefficients confirm the same conclusions. The values of the correlation coefficients for the dependence between the development of the acquired titratable acidity (SH) and the variations of fat (F), protein (P) and lactose (L) contents were as follows: r = 0.95; 0.95; -0.99 (P less than 0.001; Figs. 12, 13; Tab. II). Thus the above-mentioned "seeming" increase in the F and P contents can be explained to the extent of 92.2% from the decrease in the L content, which also causes the increase in titratable acidity to the extent of 98.0%.(ABSTRACT TRUNCATED AT 400 WORDS)     

Simulation of rotational grazing to evaluate integrated pest management strategies for Boophilus microplus (Acari: ixodidae) in Venezuela

Ranchers in Venezuela historically have controlled the cattle-fever tick, Boophilus microplus (Canestrini), with acaricide treatments of cattle but no technical planning. We developed a simulation model to evaluate cattle-tick population dynamics in systematic pasture rotation systems and Integrated Pest Management (IPM) approaches to managing ticks in the tropical dry-forest ecological zone of Venezuela. Model output showed five generations of cattle-ticks produced each year throughout the dry and rainy seasons that occur in this zone. Sensitivity analyses showed disproportionately large changes in on-host B. microplus populations in response to small changes in larval mortality rates, such as those resulting from differences in the innate resistance of cattle to tick parasitism. Simulation results with 1-6 pasture systems suggest that adjusting the graze:rest sequence with systematic rotation among 4-6 pastures could suppress, but not eradicate, tick populations.     

Effect of luteinising-hormone in vivo on ovarian cell subpopulations of newly-hatched chicks

1. We analysed the number and size of different ovarian cell subpopulations of newly-hatched chicks by ovarian cell suspension count and morphometric/stereological methods as well as delta5-3beta-hydroxysteroid dehydrogenase (delta5-3beta HSD) activity in these cells treated in vivo with LH during embryonic development. 2. Fertile White Leghorn eggs received 1 microg LH applied to the chorioallantoic membrane on days 13, 15, and 17 of incubation. All animals were killed within 24 h after hatching, the left ovary was dissected and processed. 3. The results indicate that the number of germ, pregranulosa, interstitial and undifferentiated cells was not affected by LH treatment. However, we observed an increase in the size of individual interstitial cells of the ovarian medulla. In these cells, delta5-3beta HSD activity was increased in response to LH. 4. These findings suggest that LH does not exert a proliferative effect on the cells of the prefollicular ovary of the chick and that interstitial cells can be target cells for LH, increasing their steroidogenic activity due to LH treatment.     

Survey on Myxobolus infection of the bleak (Alburnus alburnus L.) in the river Danube and in Lake Balaton

In a three-year survey of myxosporean infections of the bleak (Alburnus alburnus), involving the examination of 205 fish specimens from the River Danube and 50 from Lake Balaton, four Myxobolus species (two gill parasites, one fin parasite and a species parasitising the skeletal muscles) were detected. Two of the species could be identified as M. alburni and M. obesus. Of the other two species, the gill parasite proved to be a hitherto undescribed species which is described here as a new species by the name of M. margitae. One of the two gill-parasitic species, M. obesus, formed plasmodia in the respiratory lamellae of the gill filaments, while the plasmodia of M. margitae n. sp. were formed in the afferent artery of the primary gill filaments. The plasmodia containing spores morphologically identifiable with the species M. alburni were located in the connective tissue between the fin rays. The less frequently found muscle-parasitic Myxobolus species has not been identified precisely. The plasmodia of M. obesus were found in the fish in May and June, while those of M. alburni and M. margitae n. sp. in July and August. The prevalence of infection in fish examined in these periods was 15.5% for M. obesus, 11.5% for M. margitae and 14.0% for M. alburni.     

Monoamine oxidase activity in some brain areas of sheep after hormonal stimulation

The influence of hormonal superovulatory preparations Folistiman (450 IU FSH, Spofa, Prague) and serum gonadotropin (1500 IU PMSG, Spofa, Prague) on monoamine oxidase (MAO), the degradative enzyme of catecholamines, was investigated in some areas of the brain regulating reproductive functions (area preoptica of the hypothalamus, pituitary gland, and pineal gland) in ewes with synchronized oestrus (20 mg chlorsuperlutin) during the oestrous period using a radiochemical method. After intramuscular administration of 1500 IU PMSG, marked increase of MAO activity was found in the area preoptica (p < 0.05) and in the pituitary gland (p < 0.01) in comparison with the control group. No change occurred in MAO activity after ovarian stimulation with FSH. Administration of the above superovulatory preparations failed to induce MAO activity in the pineal gland of sheep.     

Antibacterial susceptibility patterns of Pseudomonas strains isolated from chronic canine otitis externa

Development of antibiotic resistance in bacteria is a problem of great concern. It is important to establish the convenience of antimicrobial susceptibility tests in animal infections. The aim of this study was to test the susceptibility to antibiotics of Pseudomonas strains isolated from chronic canine otitis externa. We tested 23 strains of Pseudomonas: 19 Ps. aeruginosa, three Ps. fluorescens and one Pseudomonas spp. The most effective antibiotics were tobramycin (100% susceptible), marbofloxacin (91.3%) and ceftazidime (91.3%). Ticarcillin and gentamicin, commonly used for the treatment of otitis externa also showed good results (susceptibility of strains was 86 and 65.2% respectively). Lower susceptibility was found using enrofloxacin (52.1%) probably due to its indiscriminate use. We emphasize the need for a rational policy of antibiotic prescribing in order to prevent the selection of resistant strains.     

Multivariate approach for young bull selection from a performance test using multiple traits of economic importance

This study used multivariate statistics to identify clusters of animals with similar expected progeny difference (EPD) and also identify leading traits that discriminate between bulls. Various linear selection indices based on specific selection criteria were proposed. Records were collected from 880 young Nelore bulls submitted to performance testing in central Brazil between 2001 and 2012. Pre-weaning average daily gain and weights at 210 days with direct and maternal effects were used in the analysis, in addition to post-weaning weight, scrotal circumference at 365 and 450 days, carcass finish and rib eye area. EPDs were classified into three groups, and the EPD means of two of these groups stood out and were considered important based on principal component analysis that associated higher values of direct EPD of weights, average daily weight gain and scrotal circumference. The EPDs for weight at 210, 365 and 450 days, pre- and post-weaning daily gain and scrotal circumference at 365 and 450 days were major causes of variation. Each linear selection index proposed (SI₁, SI₂, SI₃, SI₄ and SI₅) defined a specific approach meaning that a different selection index should be used depending on breeding goals and selection criteria.     

Spatial risk assessment of herd sero-status of Aujeszky's disease in a county in Hungary

A Geographic Information System (VetEpiGIS) was used to analyze the ADV (Aujeszky's disease virus) sero-status in large-scale pig units regarding certain geographical features in a county of southern Hungary. The ADV sero-statuses were collected from all swine units in Csongrád county in 1998-2000. The units' coordinates were combined with a vector graphical digital map of the county, with a resolution of 1:100,000. Logistic regression tested the associations between sero-status of large-scale units and presence of topographical features, other units and villages in the neighborhood. "Neighborhood" was defined by circular zones with radius 1-10km around the unit (in 1km increments; one logistic regression for each radius). The following topographical features showed significant positive association with the ADV seropositivity: lake (3km OR: 5.7; 5km OR: 7.5; 6km OR: 6.1; 10km OR: 5.4) and highway (5km OR: 4.2; 6km OR: 5.3). Other features had negative association with ADV seropositivity: forest (3km OR: 0.13; 4km OR: 0.15; 5km OR: 0.15; 6km OR: 0.10; 7km OR: 0.10; 8km OR: 0.23) and uninfected large-scale unit (4km OR: 0.07; 5km OR: 0.27; 6km OR: 0.32; 7km OR: 0.31).