Factors Affecting Nutrient Digestibility in Pet Food

Ⅰ.The factors of the diet

1. The source of dietary components and the absolute content of nutrients will affect the determination of digestibility. In addition to this, the effect of dietary processing on digestibility cannot be ignored.

2. Reducing the particle size of dietary raw materials can improve digestibility, thereby improving feed utilization, but it will lead to reduced productivity during feed processing, increased feed costs, and reduced mobility.

3. The processing conditions of the pretreatment chamber, particle crushing, extrusion steam granulation process or dryer can all affect the nutritional value of the feed and thus the digestibility.

4. The feeding and management of pets can also affect digestibility, such as the type and quantity of previously fed diets.

Ⅱ.The factors of the pet itself

Animal factors, including breed, age, sex, activity level, and physiological state, must also be considered when determining digestibility.

1. The influence of variety

1) In order to study the effect of different breeds, Meyer et al. (1999) performed a digestion test with 10 different canines weighing 4.252.5 kg (4 to 9 dogs per breed). Among them, the experimental dogs were fed with canned or dry commercial diets with a dry matter intake of 13g/(kg BW·d), while the Irish wolfhounds were fed with canned diets with a dry matter intake of 10g/d. (kg BW·d). Heavier breeds had more water in their stools, lower stool quality and more frequent bowel movements. In the experiment, the feces of the largest breed, the Irish wolfhound, contained less water than the Labrador retriever, suggesting that weight wasn’t the only factor to be considered. Apparent digestibility differences between varieties were small. James and McCay (1950) and Kendall et al. (1983) found that medium-sized dogs (Salukis, German Shepherds and Basset hounds) and small dogs (Dachshunds and Beagles) had similar digestibility, and in both In the experiments, the body weights between the experimental breeds were so close that the differences in digestibility were small. This point became a tipping point for the regularity of relative gut weight loss with weight gain since Kirkwood (1985) and Meyer et al. (1993). The empty gut weight of small dogs accounts for 6% to 7% of body weight, while that of large dogs drops to 3% to 4%.

2) Weber et al. (2003) studied the effect of age and body size on apparent digestibility of extruded diets. Nutrient digestibility was significantly higher in large dogs across all age groups, although these large dogs had lower stool scores and higher stool moisture content.

2. The effect of age

1) In the study by Weber et al. (2003) above, the digestibility of macronutrients in the four breeds of dogs used in the experiment increased significantly with age (1-60 weeks).

2) Shields (1993) research on French Brittany puppies showed that the digestibility of dry matter, protein and energy in 11-week-old dogs was 1, 5 and 3 percentage points lower than that of 2-4 year old adult dogs, respectively. But no differences were found between 6-month-old and 2-year-old dogs. It is still unclear whether the reduced digestibility in puppies is caused by an increase in diet consumption alone (relative body weight or intestinal length), or by a decrease in digestive efficiency in this age group.

3) Buffington et al. (1989) compared the digestibility of beagle dogs aged 2 to 17 years. The results showed that, before the age of 10, no decline in digestibility was found. At 15-17 years of age, only a small decrease in digestibility was observed.

3. The effect of gender

There are relatively few studies on the effect of gender on digestibility. Males in dogs and cats have higher feed intake and excretion than females, and lower nutrient digestibility than females, and the effect of gender differences in cats is greater than in dogs.

III. The factors of the environment

Housing conditions and environmental factors appear to influence digestibility, but studies of dogs housed in metabolic cages or mobile kennels have shown similar digestibility regardless of housing conditions.

Effective environmental factors, including air temperature, humidity, air velocity, floor coverings, insulation and temperature adaptation of walls and roofs, and their interactions, can all have an impact on nutrient digestibility. Temperature works through compensatory metabolism to maintain body temperature or absolute food intake in two ways. Other environmental factors, such as the relationship between managers and test animals and photoperiod, may have effects on nutrient digestibility, but these effects are difficult to quantify.

Post time: Jun-16-2022