Molecular Markers For Selection of Resistance to Facial Eczema

<p>The disease facial eczema is caused by the fungal metabolite sporidesmin which produces photosensitisation of animals whose liver and biliary tract have been damaged by the toxin. Sporidesmin is produced by the pasture fungus Pithomyces chartarum and affects ruminant animals that graze on contaminated pasture. Previous studies have shown that sporidesmin is metabolised in the liver and have suggested that the toxin is metabolically inactivated by enzymes in the glutathione S-transferase and cytochrome P-450 families. The activities of these enzymes were therefore measured in liver extracts from Romneys that had been selected for resistance or susceptibility to sporidesmin - induced liver damage. Although there were no differences in cytochrome P-450 CO binding spectra or cytochrome c reductase between the selection lines, resistant Romneys had greater nitroanisole O-demethylase activity and this difference was apparently enhanced two days after dosing with sporidesmin. Dose-dependent differences occurred in the absence of major hepatocellular injury suggesting that they reflected changes in enzyme activity rather than changes in tissue mass. Aminopyrine N-demethylase did not vary significantly between the selection lines. Some differences in GSH-dependent metabolism were also observed. Undosed resistant Romneys showed greater GSH-dependent metabolism of sporidesmin in a spectrophotometric assay. It is possible that glutathione S-transferase Mu or Theta isoforms had greater activity in the resistant lines as differences were observed using p-nitrobenzyl chloride and 1,2 epoxy-3-p-nitrophenoxypropanol but not with 1-chloro-2,4-dinitrobenzene or 1,2-dichloro-4-nitrobenzene that are good substrates for these isoforms. 2-D PAGE was applied to the separation of whole homogenate and soluble proteins. Variations in expression of some proteins including GST Mu isoforms were found between the selection lines. Roles of cytochrome P-450 and glutathione S-transferase in the hepatic detoxication of sporidesmin have previously been demonstrated. Results obtained in this study suggest that resistant Romneys may have greater cytochrome P-450 O-demethylase and glutathione S-transferase activities that could be responsible for increased metabolic inactivation of sporidesmin. These differences may in the future be of use in design of DNA probes to enhance detection and selection of facial eczema resistant livestock.</p>

Molecular Markers For Selection of Resistance to Facial Eczema

<p>The disease facial eczema is caused by the fungal metabolite sporidesmin which produces photosensitisation of animals whose liver and biliary tract have been damaged by the toxin. Sporidesmin is produced by the pasture fungus Pithomyces chartarum and affects ruminant animals that graze on contaminated pasture. Previous studies have shown that sporidesmin is metabolised in the liver and have suggested that the toxin is metabolically inactivated by enzymes in the glutathione S-transferase and cytochrome P-450 families. The activities of these enzymes were therefore measured in liver extracts from Romneys that had been selected for resistance or susceptibility to sporidesmin - induced liver damage. Although there were no differences in cytochrome P-450 CO binding spectra or cytochrome c reductase between the selection lines, resistant Romneys had greater nitroanisole O-demethylase activity and this difference was apparently enhanced two days after dosing with sporidesmin. Dose-dependent differences occurred in the absence of major hepatocellular injury suggesting that they reflected changes in enzyme activity rather than changes in tissue mass. Aminopyrine N-demethylase did not vary significantly between the selection lines. Some differences in GSH-dependent metabolism were also observed. Undosed resistant Romneys showed greater GSH-dependent metabolism of sporidesmin in a spectrophotometric assay. It is possible that glutathione S-transferase Mu or Theta isoforms had greater activity in the resistant lines as differences were observed using p-nitrobenzyl chloride and 1,2 epoxy-3-p-nitrophenoxypropanol but not with 1-chloro-2,4-dinitrobenzene or 1,2-dichloro-4-nitrobenzene that are good substrates for these isoforms. 2-D PAGE was applied to the separation of whole homogenate and soluble proteins. Variations in expression of some proteins including GST Mu isoforms were found between the selection lines. Roles of cytochrome P-450 and glutathione S-transferase in the hepatic detoxication of sporidesmin have previously been demonstrated. Results obtained in this study suggest that resistant Romneys may have greater cytochrome P-450 O-demethylase and glutathione S-transferase activities that could be responsible for increased metabolic inactivation of sporidesmin. These differences may in the future be of use in design of DNA probes to enhance detection and selection of facial eczema resistant livestock.</p>

Mangrove (Avicennia marina) leaves as an alternative feed resources for ruminants

The aim of this research was to get the best treatment for preserving of mangrove (Avicennia marina) leaves as an alternative feed resouces for ruminants. This research used experimental method using a completely randomized design (CRD) with 2 treatments and 5 replications for each treatment. The treatments are: P1 (Mangrove leaves silage) and P2 (Mangrove leaves hay). The variables observed in the in-vitro experiment were in-vitro rument fluid characteristics (pH, NH3, VFA), total gas production and methane gas production. The results of the in-vitro research showed that the P2 treatment (mangrove hay) produced : pH 6,67, VFA 83 Mm, NH3 5,44 mg/100 ml, total production gas for 48 hours 99,7 ml/hour, and methane gas production for 48 hours 65,05 ml/gr DM. From this research can be concluded that the best treatment for preservation of mangrove leaves (Avicennia marina) was the hay treatment based on the total gas and methane gas production. It can be concluded that the hay mangrove leaves (Avicennia marina) can be used as an alternative resource feed for ruminant animals.

76 Cattle Production’s Response to Packing Capacity Disruption

In August 2019, a fire at Tyson’s Finney County, Kansas, beef plant removed approximately 5% of U.S. beef packing capacity for 3 months. Subsequent COVID-19 pandemic-related precautions and workforce illness caused multiple packing plants across the country to decrease or stop production in the spring of 2020. Both events resulted in feedlots being unable to ship cattle at optimal finish points or according to projection. Estimates of the number of cattle backlogged during 2020 approach 1 million. Producers were faced with decisions on how to manage finished animals that could not be shipped while considering economic, animal welfare, and animal health outcomes. Many factors further complicated the situation including highly volatile markets, the possibility employee quarantine due to personal or family illness would cause operations to be under-staffed, and shortage of available pens for new cattle. Feeders had the option to slow the rate of growth of finished cattle due to the ability of ruminant animals to utilize low-energy feedstuffs or by calculating programmed rates of gain using the net energy system. Instead, many producers chose to attempt maximal rates of gain hoping persistent growth and feeding margins would offset discounts due to heavy carcass weights and excess fatness when the supply chain began moving again. Regarding new placements, the structure of the beef industry is uniquely developed to absorb cattle in stocker and backgrounding operations. This presentation will review the factors impacting cattle production and provide case-studies related to feeding at maintenance and growth rates, efficiencies, and carcass outcomes of held cattle from an operation and industry level.

169 Estimating the Environmental Impact of Livestock Operations Using the Canadian Whole-farm Model Holos Developed for Canadian Farmers

The Holos model is a Canadian whole-farm model that uses IPCC Tier II emission factors to calculate greenhouse gas (GHG) emissions from Canadian farming systems. These Tier II emission factors are Canada-specific with respect to land-based nitrous oxide emission, but are universal with respect to the livestock calculation. Here, however, Tier II is limited to ruminant animals, as so far only Tier I models are available for monogastrics. The model is designed to permit farmers to enter readily available farm management information themselves in order to calculate GHG sources and management driven mitigation practices. The presentation will provide an overview of the model and its design (interface and algorithms), and will showcase some of the scientific studies (cradle-to-farmgate) that were accomplished using the Holos model for assessing the carbon footprint of Canadian beef and dairy production systems.

Hayvan Besleme Stratejileri ile Metan Emisyonunun Azaltılması

The methods applied for yield increases per unit animal are also progressing rapidly, along with the rapid progress of agricultural and animal production in parallel with the rapidly developing population and the food demand. The increase in animal products increases the environmental impacts per unit of animal product. With the increase in animal wastes in recent years, greenhouse gas emissions have increased even more, thus negatively affecting the environment and animal health. In order to prevent this negative effect, sustainable methods and strategic measures related to animal feeding and care are important in order to reduce the emission of harmful greenhouse gases. Methane, which is the second most important greenhouse gas, is found in large amounts in the atmosphere as a molecule, the accumulation of this gas in the atmosphere more than CO₂ increases the interest in this subject. Different practices related to the nutrition of ruminant animals (use of feed additives, feeding strategies) in order to optimize rumen conditions and increase productivity per unit animal is a developing area. Sharing this information with animal breeders will also benefit the environment, and therefore human and animal health, in terms of reducing both methane and nitrogen emissions. In ruminant animals, it can cause a loss of 2-12% of the gross energy taken with the feed so that the methane gas can be removed from the body. There are many studies on feeding to reduce nitrogen losses in faeces and urine, which cause methane emissions for ruminants, and many of these studies still do not reach a permanent conclusion. The reduction in enteric CH₄ emissions to be made must be tailored to the specific needs of farmers and livestock, and to be cost-effective. In our study, it is aimed to compile animal feeding strategies and reduction of methane emissions under different conditions.