Nutrition Experiments see link below: http://nutritionexperimentshollie.weebly.com Food Analysis methods There is dry matter analysis. This is the most common test done in nutrition laboratories due to animal tissues, plant feedstuffs and more samples different in water content. If grain is bought and fed, the value of grain with 20% moisture is not going to be the same as grain with 10% moisture. Once the analysis has been done, nutrient composition is able to be expressed on a dry basis or normal fed basis, that is 90% dry matter for the majority of grains. The best way to find the dry matter is put the substance in an oven and leave it in there until all of the water has evaporated from it. It is done at a temperature of 100-105 degrees C. Moisture can be measured by moisture meters as well; these give results straight away by a probe placed into the test material. A few of these pieces of equipment need electrical conductivity for quick results. This method is not as accurate as the results given by drying the test material in the oven. Microwaves can also be used prior and after drying. Proximate Analysis This is where analytical procedures have been developed over a century ago in Germany. It is the routine description of feedstuff. There are different fractions that occur from proximate analysis these are: crude protein, ash, water, ether extract, nitrogen free extract and crude fibre. Crude protein is found by kjeldahl method. This is done by the average protein is 16% N and the kjeldahl analysis is dependent on the measurement of N in the test material. In order to convert the measured N content of a feed to crude protein, the value of N is multiplied by 6.25. E.g. calculated crude protein content of feed made up of 8% N is 50% (8%x6.25=50%). Material that is analysed first will be digested in concentrated H2S04 that converts the N to (NH4) 2S04. The mixture of cool, diluted with water, and neutralized with NaOH, alters the N into the form ionised ammonium. The sample is distilled, with the distillate made up of ammonium is titrated with acid. The analysis is precise and can be repeated however, it takes a long time and uses hazardous chemicals. Sample digestion is used more often. Ash is the mineral part of the sample determined by burning the sample in a muffle furnace at 600 degrees centigrade for 2 hours. Crude fat piece of sample that is soluble in diethyl ether (ether extract). Crude fibre piece of moisture and fat free sample which stays after digestion with weak acid and base. Low digestibility and made up of cellulose. Soluble carbohydrate (Nitrogen extract) is found by adding up percentages and subtracting the total from 100. (Laboratory base analysis, 2015). Specialised Analytical Methods There are a number of these methods and these methods are used for: animal tissue, feedstuff, mixed diets and excretion samples. Bomb calorimetry The oxygen bomb calorimeter is used for energy values of liquids solids and gases. The energy value of a sample is determined by burning it in a pressurized oxygen atmosphere. When it is burnt, the heat created allows the temperature to get higher in the water covering the container which the sample is in and the raise in temperature gives the base for calculating the energy value. It is used for extensive use for evaluating fuels e.g. natural gases and coal. It is most effective in determining digestibility of energy in feedstuff and rations. The gross energy value (got when burning) of feedstuff has slight to no direct application because you cannot tell the difference between constituents that are used well by animals and those that are not (Pond, 2005). Dry weight analysis subtract moisture content from 100 to determine the dry matter %, then divide the % of nutrient by the dry matter %, multiply the answer by 100 to give the % of nutrient on a dry matter basis. 1g of carbohydrate produces 3.5 kcal Metabolisable energy. 1g of protein produces 3.5kcal Metabolisable energy, 1g of fat produces 8.46 kcal Metabolisable energy. ME = (Protein x 3.5) + (fat x 8.46) + (carbohydrate x 3.5) kcal/ 100gms. To work out the ME content of dog food when protein is 22%, oil is 8% and ash is 7.9%. You calculate the soluble carbohydrate content (add up % of nutrients and take away from 100). Carbohydrate 49 x 3.5= 171.50 Fat 8 x 8.46 = 67.68 Protein 22 x 3.5 = 77.00 Metabolisable Energy (ME) = 316.18 100-51 = 49 Soluble energy Dry weight analysis Calculating the ME content of the following canned pedigree dog food on a dry matter basis: protein 8%, oil 6%, Ash 2%, Fibre 0.8% and moisture 79%. You have to divide the values by the dry matter. Protein 8/21 x 100= 38.09% Fat 6/21 x 100 = 28.57% Carbohydrate 4/21 x 100 = 19.04% Carbohydrate 19.04 x 3.5 = 66.64 Fat 28.57 x 8.46 = 241.70 Protein 39.09 x 3.5 = 133.30 Metabolisable energy = 441.64 (Pond, 2005: chapter 3). |
Energy requirements in sickness are calculated by RER due to being inactive. Sickness can be trauma, surgery or sepsis. this increases their energy requirements. burns: moderate RER x 1.5 severe RER x 2.0 cage rest RER X 1.25 cancer: early RER X 1.25 Late RER X 1.75 Sepsis RER X 1.5 Surgery/ trauma mild RER X 1.25 Severe RER X 1.5 Healthy pet has MER of RER X 2 however, inactive dog will need less energy and working dogs will need more. Growth (dogs) weaning to 50% adult weight MER X 2 50-80% adult weight MER X 1.5 80-100% ADULT WEIGHT MER x 1.2 Gestation (dogs) 1st third MER X 1.0 2nd third MER X 1.1 last third MER X 1.2-1.3 (Agar, 2001). The Pearson’s Square Method is used to measure the amount of feed that is needed to follow the nutritional requirement of animals and livestock. It is especially important method for farmers to use as they normally have two rations therefore they need to make sure their animals are getting the correct nutritional content. It works best when there are two feeds. The centre number is the specific animals nutritional requirement. It works by taking away the nutritional requirement for example in the chicken Pearson’s square method (18) take away crude protein (10) equals (8) then crude protein of cotton seed in the top left hand corner (40) takeaway (18) desired amount. Then you takeaway these two numbers to get (22)parts so then you add the two parts of the mix together to make (30) parts. However, this method does not work if there are more than two rations. (Simple Ration Formulation: Pearson's Square, 2010). 8/30 x 100 = 26.66% cotton seed 22/30 x 100 = 73.33% grain This is suitable for a laying chicken because they are getting a mixture of food. However, it is not good because they can selective feed, so if they leave some of it then the they are not getting the required protein. If you just had one ingredient for example, pellets you know that they are getting the nutrients that they need from it. This is because with two ingredients there is no way of monitoring how much they are eating. Pearson's square of a chicken
Soybean meal (SBM) 45% protein
Corn Gluten 45% protein Grain mixture (corn 9% and oats 12%) 60%SBM x 45/100 = 27 40% corn gluten x 45/100 = 18 Protein supplement mixture 27 + 18 = 45% 65% corn x 9/100 = 5.85 35% oats x 12/100 = 4.20 Grain mix is 5.85 + 4.20 = 10.05% 4.95/ 34.95 x 100 = 14.2 % PSM
30/34.95 X 100 = 85.8 % CM 4.95 x 60 = 3 parts SBM 4.95 x 40 = 2 parts CG This is a suitable ration for a maintenance production animal because the animal is not just getting one ingredient they are getting a few to make their food more interesting and enjoyable. They are also getting a good percentage of each ingredient allowing them to get a balanced diet. The problems with the formula are both the soybean meal and corn gluten are 45% protein and in the ration you do not need both to be that high only one amount otherwise the animal would be getting too much. Partition of energy in a pig (Energy, 2015). The gross energy that an animal has is lost in the faeces. The digestible energy is lost through gas and urine. Metabolisable energy is lost through heat. So in order to maintain the required energy the animal needs to be fed because energy is lost by bodily functions especially in production animals. The intake of food minus energy lost in faeces is called the apparent digested energy. The intake of energy (IE) of the animal is measured by collecting the faeces over a time period. Feed and faeces are examined for energy content and digestible energy (DE) is worked out by DE= IE-FE. Faeces loss can range from 10% - 80% depending on the animal (Pond, 2005). |
(Chemistry, 2015).