Standardized evaluation and rating of biofilters: II. Manufacturer''s and user''s perspective

As manufacturers of biofilters we feel that it is important that our customers have a standardized set of criteria that can be used to compare the many different commercially available biofilters on the market today. The purpose of this paper is to show how a variety of manufacturers size their own filters, establish commonalities between the methods and suggest, to the engineering community, the needs of the industry that are required to develop a uniform sizing criteria. Similarities in sizing methodologies include standard information supplied by the consumer (system volume, feed rate, etc.) as well as those estimated by the manufacturer (TAN production, and hydraulic requirements). Differences in sizing methodology include the use of in situ nitrification and system flushing. From the various examples of biofilter sizing, it is clear that manufacturers use a sizing methodology based on either an areal or volumetric TAN conversion rate (ATR or VTR). As manufacturers, we should be able to publish ATR or VTR for each of three trophic levels (oligotrophic, mesotrophic and eutrophic) with appropriate correction factors for water temperature and salinity. A standardized labeling system that would allow system designers to accurately and rapidly determine which biofilter(s) meet their needs is proposed. We leave it to the engineering community to devise a standardized scheme by which VTR values could be determined to facilitate this comparison.     

Neonatal lamb mortality: major risk factors and the potential ameliorative role of melatonin

High incidences of pre-weaning mortality continue to limit global sheep production, constituting a major economic and welfare concern. Despite significant advances in genetics, nutrition, and management, the proportion of lamb deaths has remained stable at 15–20% over the past four decades. There is mounting evidence that melatonin can improve outcomes in compromised ovine pregnancies via enhanced uterine bloodflow and neonatal neuroprotection. This review provides an overview of the major risk factors and underlying mechanisms involved in perinatal lamb mortality and discusses the potential of melatonin treatment as a remedial strategy. Supplementing pregnant ewes with melatonin enhances uterine bloodflow and fetal oxygenation, and potentially birthweight and neonatal thermogenic capacity. Melatonin freely crosses the ovine placenta and blood-brain barrier and provides neuroprotection to the fetal lamb during periods of chronic and acute hypoxia throughout gestation, with improved behavioural outcomes in hypoxic neonates. The current literature provides strong evidence that maternal melatonin treatment improves outcomes for lambs which experience compromised in utero development or prolonged parturition, though to date this has not been investigated in livestock production systems. As such there is a clear basis for continued research into the effects of maternal melatonin supplementation during gestation on pre-weaning survival under extensive production conditions.     

Economic modeling of the use of gonadotropin-releasing hormone at insemination to improve fertility in dairy cows

Economic and sensitivity analysis methods were used to evaluate financial returns from use of gonadotropin-releasing hormone (GnRH) at the time of insemination to enhance fertility of dairy cows. A computer spread sheet was used to determine the best service(s) for GnRH treatment, the increase in conception rate required for economic benefit from treatment, and how profits from GnRH treatment are affected by drug cost, herd reproductive efficiency, and production costs. Financial returns increased from use of GnRH at insemination under most herd conditions. Herds with conception rates less than or equal to 45% benefited from GnRH treatment at any 1 or 2 inseminations. Herds with conception rates greater than or equal to 60% benefited from GnRH treatment only at second or later services. Selection of second and/or third insemination as the GnRH treatment service usually resulted in the greatest total return. The enhancement of fertility necessary to achieve the break-even point with GnRH treatment at third service was 2% for low- and 5% for high-conception-rate herds. Base-line herd conception rates, estrus detection efficiency, replacement costs, value of excess days not pregnant, and cost of treatment had the greatest effect on returns from treatment. Herds with high conception rates and low replacement costs were likely to realize the least benefit from GnRH treatment at insemination. On the basis of our findings, we concluded that GnRH treatment at insemination is a profitable procedure under most herd conditions. Optimal treatment regimens for specific herds may best be determined by using herd performance and management data for calculating returns.     

In vitro degradation of bovine myofibrils is caused by μ-calpain, not caspase-3

Tenderness is a key palatability trait influencing perception of consumers of meat quality and is influenced by a multitude of factors, including postmortem proteolysis. A fundamental understanding of this biological mechanism regulating tenderness is necessary to decrease variability and increase consumer satisfaction. However, reports regarding the enzyme systems involved in postmortem tenderization are conflicting. Therefore, the objective of this study was to determine if caspase-3 is responsible for the degradation of myofibrillar proteins during aging. Bovine semitendinosus muscles were removed from 2 carcasses. Muscle from the left side of each carcass was excised 20 min postmortem and utilized for in vitro analysis of protein degradation. Muscle strips were dissected from the semitendinosus, restrained to maintain length, and placed in a neutral buffer containing protease inhibitors. Upon rigor completion, myofibrils were isolated from each strip and sarcomere length was determined. Samples with similar sarcomere lengths were selected to minimize the effect of sarcomere length on proteolysis. Myofibrils were then incubated at 22°C with μ-calpain, caspase-3, or μ-calpain + caspase-3 for 0.25, 1, 3, 24, 48, or 72 h at optimum pH for enzyme activity. The semitendinosus from the right side of each carcass was excised 1 d postmortem, cut into 2.54-cm steaks, vacuum-packaged, and allowed to age for 2, 4, 7, or 10 d to evaluate normal protein degradation during beef aging. Proteolysis of troponin T, α-actinin, and desmin was monitored using SDS-PAGE and Western blotting techniques, whereas proteolysis of titin and nebulin was monitored using SDS-vertical agarose gel electrophoresis and Western blotting. Analysis of Western blots revealed no change in abundance of intact troponin T, desmin, titin, or nebulin over time in myofibrils incubated with caspase-3. However, abundance of these proteins subjected to digestion with μ-calpain and μ-calpain + caspase-3 revealed degradation patterns similar to in situ samples. No degradation of α-actinin was observed in in vitro or in situ samples. Results of this study indicate μ-calpain, not caspase-3, is responsible for the degradation of key myofibrillar proteins during beef aging.     

Induction of anaesthesia in dogs and cats with propofol

Propofol was used to induce anaesthesia in 89 dogs and 13 cats of either sex, various breeds and of widely different ages and weights; they varied considerably in physical condition and were anaesthetised for a variety of investigations and surgical procedures. They were premedicated with acepromazine, papaveretum, diazepam, pethidine, atropine and scopolamine in different combinations. After induction with propofol, anaesthesia was maintained with halothane, isoflurane, methoxyflurane and enflurane and, or, nitrous oxide. The mean (+/- sd) induction doses of propofol in unpremedicated and premedicated animals were 5.2 +/- 2.3 mg/kg and 3.6 +/- 1.4 mg/kg respectively for dogs, and 5.0 +/- 2.8 mg/kg and 5.3 +/- 4.3 mg/kg for cats. There were no differences between the sexes. Premedication did not affect recovery times. The incidence of side effects was very low. One dog showed evidence of pain when propofol was injected. No incompatibility was observed between propofol and the premedicants and other anaesthetic agents used.     

Pathology of surgically resected tissue from 305 cases of anal furunculosis in the dog

Data are presented from a series of 305 cases of canine anal furunculosis in which the German shepherd dog was over-represented (n = 255) compared with dogs of other breeds (n = 50). The age and sex distribution in each group was similar. The nature and severity of pathological change in surgically resected tissue from German shepherd dogs was compared to that in dogs of other breeds. The microscopic appearance of lesions in each group was similar and did not suggest a simple reason for the breed predisposition in this disorder.