Water-dispersible clay after wetting and drying cycles in four Brazilian oxisols

Widespread intensive land use in the seasonal tropics can damage the physical stability of aggregates. Similar damage can be expected from wetting and drying cycles causing aggregate fragmentation and, consequently, leading to an increase in their specific area and exposure of internal electric charges. Thus, we hypothetised that the influence of wetting and drying cycles is dependent on the mineralogical composition of oxisols (latosols) and it is higher in soils with low aggregate stability. A greenhouse experiment was carried out to test this hypothesis in highly weathered soils from Brazil, all with variable-charge clays and highly stable aggregates. Wetting and drying cycles were defined from the quantity of water available between field capacity and the permanent wilting point. Soil columns were submitted to 0, 2, 6, 9, 12, 15 and 18 wetting and drying cycles. After each number of wetting and drying defined physical and chemical properties were determined. Statistical analysis, such as simple and multiple linear regression and Pearson's correlation were performed, showing significantly correlated WDC contents with wetting and drying cycles. The obtained results led to the conclusion that there was a close interdependence among mineralogical composition, aggregate stability and WDC influenced by wetting and drying cycles. Soils of reduced aggregate stability like kaolinitcs made them more susceptible to the action of wetting and drying on the WDC. Changes in the WDC with wetting and drying cycles showed correlated with eletrochemical properties.     

Habitat selection by the pale-headed brush-finch (Atlapetes pallidiceps) in southern Ecuador: implications for conservation

The pale-headed brush-finch (Atlapetes pallidiceps) is threatened with extinction due to habitat loss, but very little is known about its ecological requirements. We used multiple logistic regression to study habitat selection of this species at landscape, territory, and nest site scales in order to make recommendations about effective management. Habitat selection by the sympatric stripe-headed brush-finch (Buarremon torquatus) was examined with the same methods in order to analyse interspecific resource partitioning and potential competition. The pale-headed brush-finch selected semi-open habitat types with intermediate scrub heights, and avoided forests. Nest sites depended on the presence of vines or bamboo. By contrast, the stripe-headed brush-finch chose dense habitat with low ground cover under tall vegetation and avoided semi-open habitat. The two species had overlapping territories but differed significantly in microhabitat use and the use of vegetation strata. We found no convincing evidence that the stripe-headed brush-finch displaces the pale-headed brush-finch from optimal habitat. The preservation of semi-open scrubland maintained by low-intensity grazing is suggested for future conservation of the pale-headed brush-finch.     

Effect of water and feed withdrawal and health status on blood and serum components, body weight loss, and meat and carcass characteristics of Holstein slaughter cows

During marketing, cattle may be exposed to periods of water deprivation. The impact of water and feed access and health status on the physiological well-being and carcass characteristics of Holstein slaughter cows during preslaughter marketing was studied through analysis of serum components, BW loss percentage, and fresh meat composition. Ninety-one multiparous Holstein cows (609 ± 89 kg mean BW, 2.9 ± 0.5 mean BCS, varying stage of lactation) were purchased over 3 wk in 3 groups (n = 31, 29, and 31) at a terminal market in central Wisconsin. Each cow was screened to determine health status (sick or not sick) and randomly assigned to 1 of 3 water and feed withdrawal treatment pens (AL, ad libitum access to water for 36 h; 18H, 18 h of ad libitum access to water followed by 18 h of water withdrawal; 36H, 36 h of water withdrawal; all 3 treatments included 36 h of feed withdrawal) in a randomized complete block arrangement with repeated measures for serum components. Blood samples were collected by tail venipuncture at 0, 9, 18, 27, and 36 h of each treatment. Ambient temperatures were 1.9 ± 6.2°C during the trial period, which occurred over a 3-wk period in March and April 2007 near Arlington, WI. No difference (P > 0.05) was observed in mean serum cortisol in AL (18.41 ± 2.17 ng/mL) or 36H (22.98 ± 2.17 ng/mL). Mean serum glucose was greater (P < 0.05) in 36H pens (78.15 ± 0.77 mg/dL) than AL (75.91 ± 0.77 mg/dL). Mean serum creatinine was greater (P < 0.05) in 36H pens (0.71 ± 0.03 mg/dL) than AL (0.60 ± 0.03 mg/dL). The 36H pens also displayed increased (P < 0.05) serum albumin, anion gap, Ca, Cl, Na, cholesterol, and aspartate aminotransferase over AL. Greater (P < 0.05) mean percentage BW loss was observed in 36H pens (5.2 ± 0.6%) than AL (3.1 ± 0.6%). Mean muscle protein (%) was greater (P < 0.05) in 36H (22.2 ± 0.4%) than 18H (21.3 ± 0.4%). Mean muscle moisture (%) was greater (P < 0.05) in AL and 18H (75.3 ± 0.4% and 75.2 ± 0.4%) than 36H. Mean 24-h pH values were 5.92 (AL), 5.92 (18H), and 5.81 (36H; SE = 0.04) and were not different (P < 0.05). Observed pH and color values indicated a borderline dark-cutter state across all cattle in the study, regardless of water and feed access treatment. Based on these results, water and feed withdrawal in lairage should not exceed 18 h during the marketing of Holstein slaughter cows acclimated to springtime conditions to maintain BW, serum component concentrations, and fresh meat composition.     

Reproductive performance in South Australian dairy herds

SUMMARY Herd breeding records (161) were examined from a random 10% sample of dairy farms (96) in South Australia with more than 40 cows and suitable breeding records for 1988 and/or 1989. Of these farms, 53 (55.2%) had a year-round calving pattern, 42 (43.8%) claimed to be seasonal and one was changing from a year-round to a seasonal pattern. Only 14.6% of farmers observed oestrous behaviour outside milking times and 18.8% used tailpaint. Overall, the average proportion of unobserved heats was estimated to be 32%. Artificial insemination (AI) was carried out on 85.4% of farms (16.7% used AI alone and 68.7% also used bulls) of which 32.9% used commercial technicians and 67.1% were do-it-yourself operators. Overall, the average 30-day submission rate was 59.9% and the average 49-day non-return to service rate was 58.9%. Investigation into the probable causes of suboptimal reproductive performance gave a tentative diagnosis of inefficient oestrous detection, deferral of service, inadequate nutrition, poor AI technique, insufficient bulls, and venereal/other diseases in 69.1, 32.1, 27.2, 28.4, 13.6 and 7.4% of records, respectively.     

The use of infrared thermography as an early indicator of bovine respiratory disease complex in calves

Bovine respiratory disease (BRD) complex causes considerable distress to domestic livestock and economic hardship to the beef industry. Furthermore, the resulting extensive use of antimicrobial treatments is a growing concern from the perspective of facilitating antibiotic resistant microbes. The earlier detection of BRD would enable an earlier, more targeted treatment regime and earlier isolation of infected individuals. The objective of the present study was to investigate the use of non-invasive infrared thermography in the early detection of BRD in cattle. Studies were conducted on 133 head of weaned calves. Data demonstrated that infrared thermography was able to identify animals at early stages of illness, often several days to over one week before clinical signs were manifest. Data indicated that 4-6 days prior to the onset of clinical symptoms of BRD, greater positive and negative predictive values and test efficiency for infrared thermography (80%, 65% and 71%, respectively) compared to the industry standard practice of clinical scoring (70%, 45% and 55%, respectively).     

Polymers, fractals, and ceramic materials

Concepts borrowed from polymer science have been applied to tailor the properties of inorganic materials, especially those derived from amorphous precursors. Fractal geometry can be used to characterize macromolecular precursors and to relate their structures to kinetic growth processes. Within the silica system, for example, it is possible to manipulate the conditions of solution polymerization to yield a variety of macromolecules from branched chains to smooth colloidal particles.     

Beef production from cull dairy cows: a review from culling to consumption

Although more than 3 million head of dairy cows enter the food supply chain in the U.S. every year, research on this topic remains limited and scarce. Meat production from dairy cows is a significant component of beef production, accounting for almost 10% of U.S. commercial beef production. Thus, the purpose of this review is to demonstrate the importance of dairy cows as a beef source, and to provide an overview on topics from farm to meat product—culling, marketing, transportation, welfare, body composition and its relationship with lactation particularities, carcass characteristics, meat quality, and traceability. Current scientific evidence has shown that culling a dairy cow at an appropriate time has beneficial effects on cow welfare and, consequently, cow value. During marketing the dairy cow is visually evaluated for health and factors associated with its expected carcass value; thus, marketing a well-conditioned cow will ensure that the animal is fit for transportation and provides high carcass yield. However, limitations such as low body condition score, lameness or mobility problems, and visual defects remain persistent. Even though beef harvest plants accommodate cows in all body composition states, the current carcass grade system does not reflect the mature cow industry needs. Therefore, improvement of the grading system could maximize carcass utilization and increase cow carcass value by recognizing subprimal cuts that could be merchandised as whole muscle cuts. Lastly, implementation of a traceability system would unify information from the farm to harvest assisting the industry in making further advancements.     

An evaluation of anthelmintic properties,assessed using faecal nematode egg counts,of New Zealand native flax (Phormium tenax)

AIM: To investigate the anthelmintic properties of New Zealand native flax (Phormium tenax) for cattle, using a faecal egg count reduction test (FECRT).

METHODS: Twenty-six heifer calves with high (>300 epg) faecal nematode egg counts (FEC) were paired into two groups and fed either chopped flax leaves ad libitum, or barley straw at an equivalent dry matter (DM) rate, from Day 0–7; all were supplemented with 1.5 kg/head/day cereal feed supplement. On Days 8–10, all heifers were fed a common diet of 3.5 kg DM/ head/day barley straw and 1.5 kg/head/day cereal feed supplement. Heifers were weighed and faecal samples were collected on Days —6, 0, 7, and 10; samples were analysed in triplicate for FEC. The nutritive value of the flax and straw was analysed.

RESULTS: Both the flax and straw had low dry matter digestibility (DMD) and protein content. Although the flax-fed claves grew more than the controls, this may have been related to gut fill. Total daily faecal egg output was similar for flax and straw groups on Day 7 (14.7 vs 15.0 x 10⁶ eggs/day, respectively) and Day 10 (14.9 vs 15.1 x 10⁶ eggs/day, respectively). There was no difference in the change in FEC with time between the calves fed flax or straw diets.

CONCLUSION: Consumption of flax leaves did not reduce FEC in calves with a mixed nematode infection.     

The effect of individual liveweight and use of teaser rams prior to mating on the reproductive performance of ewe hoggets

AIM: To determine the effects of liveweight (LW) and use of teaser rams prior to mating on both the mating performance and pregnancy rate of ewe hoggets.

METHODS: Romney hoggets (n=841) were weighed and randomly assigned to one of two treatment groups; either exposed to seven harnessed, vasectomised (teaser) rams for 17 days prior to the breeding period (n=283); or not exposed to teaser rams (unteased, n=558). Harnessed Perendale rams were then introduced for two oestrous cycles. Using crayon marks, hoggets were identified as having been mated during the first 17 days only, during the second 17 days only, during both periods, or not mated. All mated hoggets were then scanned for pregnancy using ultrasound, 48 days after the end of the breeding period, and identified as being either non-pregnant, or as single-, twinor triplet-bearing.

RESULTS: Hoggets mated in either the first 17 days only or in both the first and second 17-day periods were heavier than those mated in the second period only (p<0.001). Those mated in the first or second 17-day period only, and those mated in both periods were all heavier prior to mating than those not mated at all (p<0.001). Twin-bearing hoggets were heavier than both their single-bearing and non-pregnant counterparts (p<0.001). A greater proportion of the teased hoggets were mated in the first 17 days only compared with unteased hoggets (62.6 vs 32.1%; p<0.001). In contrast, more of the unteased hoggets were marked in the second 17-day period only (p<0.001). A greater proportion of mated, unteased hoggets were found to be non-pregnant in comparison to their teased counterparts (17.8 vs 11.2%; p=0.02).

CONCLUSIONS: Heavier hoggets at breeding were more likely to be mated in the first 17 days of the breeding period and more likely to be twin-bearing. Use of teaser rams for 17 days prior to the breeding period increased the proportion of hoggets mated in the first 17 days, increased conception rates, and thus increased the proportion of pregnant hoggets. These results indicate that farmers should utilise teasers for 17 days prior to commencement of the breeding period and avoid mating hoggets that weigh below 36 kg.