In a December discussion with Denis Bourdeau, he suggested I check the feed I was using to verify it met the necessary 2500 "megaCal" criteria required to grow fryers at an optimum rate. He also said that he had found it necessary to contract to a Quebec feed supplier to obtain a supply of feed that was above 2500 "megaCals,"- and to have a coxistat included.

Shortly after Christmas, I was visited by Brian Tapscott, the OMAFRA specialist in alternate livestock.

At that time, I asked him to send me some definitive information on "megaCals" and their importance to us. The following facts are lifted from "Rabbit Feeding and Nutrition" by Peter R. Cheeke.

Proteins: Proteins are essential components of animal tissue. Muscle tissue is largely protein. All enzymes, which facilitate chemical reactions in the body, are proteins. Proteins are composed of small molecules called amino acids. All amino acids contain one or more amino groups (NH2), thus all amino acids contain nitrogen. The protein content of feeds is commonly measured by analysis for nitrogen.

Energy Measurements: Basic definition is Calorie. It is equal to the heat energy required to raise the temperature of 1 litre of fresh water at room temperature by 1°C. Also, 1 kilocalorie (kcal) = 1000 calories, and 1 megacalorie (mcal)= 1000 kcal. When referring to the caloric rating of feed, they are considered kcal/kg of feed, ie: 2500 kcals per 1 kg. (A 6 oz portion of this feed would total 426 kcals)

The three nutrient categories that can serve as energy sources are carbohydrates, fats, and protein.

Energy Requirements in Rabbits: A 10 pound rabbit requires a minimum of 219 kcal energy intake per day to remain alive. This requirement must be met before any productive functions are accomplished.

At levels below a 2500 kcal/kg feed diet, intake may not be adequate to provide sufficient gross energy daily energy (DE) intake for maximum gain. DE intakes required to support a high growth rate (45g/day) are shown in the table below:

Daily Energy Intake Requirements of the Growing Meat Rabbit Gaining 45 g/day

Energy requirements are greatest for lactating does, and are estimated at four or more times the maintenance requirement at peak lactation. It is estimated a doe would require a total daily caloric intake of 1092 kcal to maintain a 300 g yield of milk a day. This exceeds the feed intake capacity of a NZ doe, therefore the use of high energy lactation diets for rabbits would appear to be warranted.

Energy Toxicity: Almost all nutrients are toxic when consumed in excessive quantities. The animal body has no mechanisms for excreting energy consumed in excess of requirements. Excess calories are stored in adipose tissue as body fat. For this reason it is necessary to restrict the feed to keep rabbits in desirable body conditions.

Acknowledgment to Brian Tapscott, OMAFRA