Animal Science MCQ Multiple Choice Questions Answers - Page 2 for Practice
31. Which mineral must be supplied at high levels in laying hen diets to ensure adequate eggshell structural strength?
Correct Answer is: Calcium
Solution:
Laying hens require elevated dietary calcium (around 3.5-4.0%) because eggshells are composed primarily of calcium carbonate.
32. Johne's disease, a chronic intestinal infection in cattle causing severe diarrhea and weight loss, is caused by which pathogen?
Correct Answer is: Mycobacterium avium subsp. paratuberculosis
Solution:
Johne's disease (paratuberculosis) is caused by Mycobacterium avium subsp. paratuberculosis, leading to irreversible intestinal wall thickening.
33. What is the primary disaccharide carbohydrate present in mammalian milk?
Correct Answer is: Lactose
Solution:
Lactose is the main sugar in mammalian milk, synthesized in the mammary gland from glucose and galactose.
34. Which hormone is primarily responsible for milk letdown in mammals?
Correct Answer is: Oxytocin
Solution:
Oxytocin causes the contraction of myoepithelial cells surrounding the alveoli in the mammary gland, stimulating milk letdown.
35. Elevated blood or salivary concentrations of which hormone are most commonly measured to assess acute physiological stress in animals?
Correct Answer is: Cortisol
Solution:
Cortisol is a major glucocorticoid hormone released by the adrenal cortex during physiological stress responses.
36. What type of specialized cecal feces do rabbits re-ingest directly from the anus to recycle essential nutrients such as B vitamins and microbially synthesized protein?
Correct Answer is: Cecotropes
Solution:
Cecotropes are soft, nutrient-rich fecal pellets produced in the cecum that rabbits re-ingest to recover vital vitamins and amino acids produced by cecal microbes.
37. What term describes the phenomenon where different animal genotypes perform or respond differently when exposed to distinct environmental conditions?
Correct Answer is: Genotype-environment interaction
Solution:
Genotype-environment interaction (GxE) occurs when the relative performance of different genotypes changes depending on the environmental conditions under which they are evaluated.
38. What is the standard incubation period required for domestic turkey eggs to hatch?
Correct Answer is: 28 days
Solution:
Domestic turkey eggs require an incubation period of 28 days to hatch, compared to 21 days for domestic chicken eggs.
39. Which anatomical structure allows a nursing calf to direct milk straight from the esophagus to the omasum and abomasum, bypassing the un-fermented rumen?
Correct Answer is: Reticular groove
Solution:
The reticular (or esophageal) groove is a muscular fold that reflexively closes in suckling young ruminants, creating a channel that bypasses the reticulorumen.
40. In chemical feed analysis, an increase in which fiber fraction is most strongly associated with a decrease in the overall digestibility of a forage?
Correct Answer is: Acid Detergent Fiber (ADF)
Solution:
Acid Detergent Fiber (ADF) contains cellulose and indigestible lignin; higher ADF percentages directly correlate with reduced forage digestibility.
41. Which equine stereotypic behavior involves a horse grasping a fixed wooden or metal object with its upper incisors, leaning back, and drawing air into the esophagus?
Correct Answer is: Cribbing
Solution:
Cribbing (or crib-biting) is an oral stereotypic habit where a horse arches its neck, grasps a solid object with its incisors, and swallows air.
42. Grass tetany, a potentially fatal metabolic disorder in spring-grazing cattle, is caused by an acute physiological deficiency in which mineral?
Correct Answer is: Magnesium
Solution:
Grass tetany (hypomagnesemia) occurs when cattle graze rapidly growing, cold-season pastures that are low in available magnesium, leading to muscle spasms and tetany.
43. Which water quality parameter measures the total concentration of dissolved inorganic salts and is a primary consideration in aquatic species culture?
Correct Answer is: Salinity
Solution:
Salinity measures total dissolved salts (expressed in parts per thousand) and determines whether an aquaculture environment is suitable for freshwater, brackish, or marine species.
44. Post-mortem muscular rigidity (rigor mortis) sets in when muscle cells exhaust their supply of which essential molecule needed to detach myosin heads from actin filaments?
Correct Answer is: Adenosine triphosphate (ATP)
Solution:
Rigor mortis occurs when ATP reserves are depleted post-mortem, preventing actin-myosin cross-bridges from breaking and leaving muscles in a fixed, rigid state.
45. In poultry digestion, which organ is responsible for the mechanical grinding of feed?
Correct Answer is: Gizzard
Solution:
The gizzard (ventriculus) contains strong muscular walls and grit to mechanically grind ingested food.
46. What parameter, measured in micrometers (microns), serves as the primary standard for grading raw wool quality and determining market value?
Correct Answer is: Fineness
Solution:
Wool fineness refers to average fiber diameter; smaller micron measurements indicate finer wool, which yields softer, higher-value textiles.
47. Which hormone synthesized and released by the anterior pituitary gland directly stimulates alveolar epithelial cells in the mammary gland to synthesize milk?
Correct Answer is: Prolactin
Solution:
Prolactin is the primary hormone secreted by the anterior pituitary that triggers and maintains milk synthesis (lactogenesis) within mammary secretory cells.
48. Which endoparasite, known as the large roundworm of swine, leaves distinct fibrous scarring ('milk spots') on the liver during its larval migration?
Correct Answer is: Ascaris suum
Solution:
Larvae of *Ascaris suum* travel through the intestinal wall to the liver during their migration cycle, leaving white fibrous lesions known as 'milk spots'.
49. Which dairy cattle breed is renowned for producing milk with the highest average concentration of butterfat and protein solids?
Correct Answer is: Jersey
Solution:
Jersey cattle yield milk with significantly higher percentages of milk fat (often exceeding 4.8%) and total solids compared to other major dairy breeds.
50. What digestive metabolic disorder occurs in feedlot cattle fed high-concentrate grain diets, characterized by rapid fermentation and a rumen pH drop below 5.5?
Correct Answer is: Rumen acidosis
Solution:
Rumen acidosis develops when excessive intake of rapidly fermentable carbohydrates causes volatile fatty acid and lactic acid accumulation, lowering rumen pH.
51. Because of their continuous non-collapsible air capillaries and air sacs, how many complete cycles of inhalation and exhalation does an avian respiratory system require to move a single volume of air through the entire path?
Correct Answer is: Two
Solution:
Avian respiration requires two full breathing cycles (inhalation 1, exhalation 1, inhalation 2, exhalation 2) to move a single bolus of air entirely through the system.
52. Newborn piglets raised in modern indoor confinement housing are routinely administered an intramuscular injection of which nutrient to prevent severe nutritional anemia?
Correct Answer is: Iron
Solution:
Piglets are born with minimal iron stores, and sow milk is low in iron; without supplemental iron injections, piglets rapidly develop iron-deficiency anemia.
53. What term describes a form of gene interaction where an allele at one genetic locus suppresses or alters the expression of alleles at a completely different locus?
Correct Answer is: Epistasis
Solution:
Epistasis is a non-allelic gene interaction where one gene masks or modifies the phenotypic expression of a second independent gene locus.
54. The framework of the 'Five Freedoms', widely accepted in animal science, was originally established to benchmark acceptable welfare standards for which category of animals?
Correct Answer is: Farm animals
Solution:
The Five Freedoms were developed following the UK's 1965 Brambell Committee report to ensure baseline physical and mental well-being for livestock in farming systems.
55. In horses, which section of the hindgut serves as the principal chamber for anaerobic microbial fermentation of dietary structural carbohydrates?
Correct Answer is: Cecum and large colon
Solution:
Horses are hindgut fermenters whose expansive cecum and large colon contain dense microbial populations that breakdown cellulose and hemicellulose into volatile fatty acids.
56. What is the average gestation length for a mare (female horse)?
Correct Answer is: 336 days
Solution:
Horses have an average gestation period of approximately 11 months, or about 335 to 340 days.
57. Which hormonal drug class is routinely administered in cattle reproductive management to cause regression of the corpus luteum (luteolysis) and synchronize estrus?
Correct Answer is: Prostaglandins (PGF2a)
Solution:
Prostaglandin F2 alpha (PGF2a) destroys the functional corpus luteum on the ovary, causing progesterone levels to decline and permitting the cow to return to estrus.
58. Which mechanism is the primary method of heat loss for swine in high ambient temperatures, given their lack of functional sweat glands?
Correct Answer is: Panting and wallowing
Solution:
Pigs lack functional sweat glands, relying primarily on panting for evaporative cooling and wallowing in water or mud.
59. Bovine Spongiform Encephalopathy (BSE) is caused by which type of infectious agent?
Correct Answer is: Prion
Solution:
BSE, commonly known as mad cow disease, is caused by misfolded infectious proteins known as prions.
60. What ovarian structure secretes progesterone to maintain pregnancy in mammals?
Correct Answer is: Corpus luteum
Solution:
The corpus luteum develops from the ruptured follicle post-ovulation and produces progesterone needed to sustain pregnancy.
