Topics:
Animal Nutrition, Animal Refresher
Preferred Animals for Digestibility Trials
In digestibility trial, ____________ animals are preferred:
- Female
- Males
- Castrated males — Correct Answer
- Castrated female
Explanation:
Correct Answer: Castrated males
Castrated males are preferred in digestibility trials because (a) they allow separate collection of faeces and urine (unlike females where separation is difficult), and (b) castration removes the hormonal influence of testosterone, reducing variation in metabolism and making results more uniform.
Preference Hierarchy in Digestibility Trials
| Animal Type | Preference | Reason |
|---|---|---|
| Castrated males | Most preferred ✔ | Separate urine/faeces + reduced hormonal variation |
| Normal males | Second preference | Separate urine/faeces but hormonal variation present |
| Females | Least preferred | Urogenital anatomy makes separate collection difficult |
Digestibility Trial — Key Rules
- Only faeces are collected in digestibility trial
- Both faeces AND urine collected in metabolic trial
- Preliminary period: 10–12 days (ruminants); 7–10 days (horse & swine)
- Collection period: 7–10 days (all species)
- In poultry: digestibility determined surgically or chemically (faeces and urine exit via same cloaca)
Why Other Options Are Wrong
- Female → difficult to separately collect faeces and urine; least preferred
- Males → second preference; castrated males are preferred over intact males
- Castrated female → not a standard preference; castrated males are the established choice
📚 About this Topic — Animal Nutrition
This multiple choice question is from Animal Nutrition, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Nutrition to strengthen your preparation.
