QCAA Agricultural Science Animal production B
15 sample questions with marking guides and sample answers
The table contains mean values for feed intake, feed conversion ratio, average daily weight gain and end-of-trial fat depth of feedlot lambs that were given feeds formulated at different energy levels.
| Feed | Intake (kg/day) | Feed conversion ratio | Average daily gain (g/day) | Fat depth (mm) |
|---|---|---|---|---|
| Low energy | 6 | |||
| Medium energy | 11 | |||
| High energy | 15 |
Contrast the results of using the different feeds. Draw conclusions about the best feed for fat lamb production.
Reveal Answer
High and medium energy feed resulted in a similar lower feed intake compared to low energy feed (2.3 kg/day vs. 1.75 kg/day) and similar lower feed conversion ratios (5.1 vs. 4).
Both medium and high energy feeds produced higher average daily gains (520 g/day vs. 476 g/day) and fat depth (15 mm vs. 6 mm) at the end of the trial.
Measured values for medium and high energy feeds suggest a significant difference compared to mean values for low energy feeds.
In conclusion, to produce fat lambs in a shorter period, higher energy feeds should be provided, to increase production (i.e. average daily gain) and potentially be the better option in terms of feed costs (i.e. food conversion ratio) for optimum production.
| Descriptor | Marks |
|---|---|
Contrasts feed intake and FCR data | 1 |
Contrasts ADG and fat depth data | 1 |
Draws an appropriate conclusion regarding higher energy feed and increased production | 1 |
Draws an appropriate conclusion regarding high energy feed and feed costs for optimum production | 1 |
The table identifies the minimum requirements for different lamb export markets.
| Market segment | Liveweight range (kg) | Carcass weight range (kg) | Preferred fat score |
|---|---|---|---|
| Heavy export | 38–64 | 20–30 | 2 to 4 |
| Light export | 25–35 | 10–16 | 2 |
| ‘Hajj’ market | 35–41 | 18–22 | No preference |
Identify the lamb that is best suited to the heavy export market.
Liveweight: 50 kg, Carcass weight: 27 kg, Fat score: 1
Liveweight: 40 kg, Carcass weight: 23 kg, Fat score: 5
Liveweight: 40 kg, Carcass weight: 22 kg, Fat score: 3
Liveweight: 35 kg, Carcass weight: 19 kg, Fat score: 2
Reveal Answer
Liveweight: 50 kg, Carcass weight: 27 kg, Fat score: 1
This option is incorrect because the fat score of 1 is below the preferred range of 2 to 4, even though the weights meet the requirements.
Liveweight: 40 kg, Carcass weight: 23 kg, Fat score: 5
This option is incorrect because the fat score of 5 exceeds the preferred range of 2 to 4, despite the weights falling within the correct limits.
Liveweight: 40 kg, Carcass weight: 22 kg, Fat score: 3
This option is correct because the liveweight (), carcass weight (), and fat score (3) all fall within the specific ranges defined for the heavy export market.
Liveweight: 35 kg, Carcass weight: 19 kg, Fat score: 2
This option is incorrect because the liveweight () and carcass weight () are too low for the heavy export market, fitting the light export category instead.
Which management strategy would control pests and diseases in an extensive animal industry?
visual inspections of poultry sheds
removing animal waste from a cattle feedlot
selection of short-coated cattle for animal production
maintenance of pastures in free-range egg production
Reveal Answer
visual inspections of poultry sheds
Poultry sheds are characteristic of intensive farming systems where animals are housed in confinement, rather than extensive systems which utilize large areas of land.
removing animal waste from a cattle feedlot
Cattle feedlots are intensive production systems with high stocking densities and high inputs, whereas extensive industries rely on grazing over large areas.
selection of short-coated cattle for animal production
In extensive systems where individual animal treatment is labor-prohibitive, breeding for genetic traits like short coats provides natural resistance to external parasites such as ticks.
maintenance of pastures in free-range egg production
Free-range egg production is generally considered a semi-intensive or intensive industry due to the high level of daily management, feeding, and labor required compared to extensive grazing.
Explain the difference between animal welfare and animal ethics, using a specific, intensive animal agricultural industry as an example.
Reveal Answer
Animal ethics looks at whether the production system should be carried out by public perception, whereas animal welfare is measurable by using a set of standards.
For example, in caged egg production systems, there is the public perception that this system should not be used to farm egg layers due to restrictions in space and interfering with the perceived animal rights of chickens.
Animal welfare in caged egg production systems is where there is a set minimum standard of requirements (e.g. size for cages, water dripper numbers and feed areas available to the egg layer).
| Descriptor | Marks |
|---|---|
identifies animal ethics issue in relation to their chosen industry | 1 |
identifies animal welfare concept in relation to their chosen industry | 1 |
explains the difference between animal welfare and ethics | 1 |
The table shows nutrient composition of the feeds available for dairy cattle on a farm.
| Feed | Crude protein (g/kg DM) | Metabolisable energy (MJ/kg DM) | Dry matter (%) |
|---|---|---|---|
| Silage | 120 | 9.5 | 54 |
| Hay | 140 | 9.9 | 87 |
| Barley | 130 | 11.2 | 90 |
| Lupin | 380 | 12.9 | 88 |
| N-fertilised turnip leaf | 190 | 12.5 | 14 |
If a ration consisting of 3 kg silage, 5 kg barley and 2 kg N-fertilised turnip leaf was supplied to each animal, what would be the total available crude protein and metabolisable energy?
| Crude protein (g) | Metabolisable energy (MJ) | |
|---|---|---|
| A | 1390 | 120 |
| B | 1159 | 91 |
| C | 998 | 82 |
| D | 833 | 69 |
Row A
Row B
Row C
Row D
Reveal Answer
Row A
This option incorrectly calculates nutrients based on the fresh weight ('as fed') rather than the dry matter content. For example, it calculates Crude Protein as g, ignoring the water content in the feeds.
Row B
This is an incorrect calculation. To find the correct values, the fresh weight must first be converted to dry matter mass before applying the nutrient concentrations.
Row C
This is an incorrect calculation. The correct method requires determining the dry matter (DM) portion of each feed component (e.g., Turnip leaf is only DM) before summing the protein and energy.
Row D
First, calculate the dry matter (DM) mass: Silage ( kg), Barley ( kg), and Turnip ( kg). Then sum the nutrients: CP is g, and ME is MJ.
Describe what market specifications are in agriculture and provide two examples for a meat animal in the domestic market.
Reveal Answer
Market specifications are the quality standards required by the buyers of the product.
Two examples are carcass weight and fat depth.
| Descriptor | Marks |
|---|---|
Describes market specifications | 1 |
Provides one example of a specification | 1 |
Provides a second example of a specification | 1 |
The Varroa mite is a honeybee parasite that has a major impact on overseas honey and related enterprises, killing large populations of bees and weakening colonies. If uncontrolled, Varroa mite infestation in honeybee colonies severely impacts honey production, but can also affect a wide range of pollination-reliant crops.
Identify two management strategies that beekeepers or biosecurity officers could implement to restrict the movement of Varroa mite outside of an infested area.
Reveal Answer
One management strategy is to restrict physical movement of hives outside the infested area.
A second management strategy is to routinely monitor hives and report any unexpected hive deaths, production abnormalities and/or deformities to relevant biosecurity officers.
| Descriptor | Marks |
|---|---|
identifies a strategy | 1 |
identifies a second strategy | 1 |
Identify another pest associated with an agricultural animal of regional importance and explain its effect on this animal.
Reveal Answer
An example of a regional pest is Barber’s pole worm in sheep.
While the worms in the stomach are feeding on the sheep’s blood, the animal will lose condition, which will negatively affect its production.
| Descriptor | Marks |
|---|---|
identifies the pest and associated animal | 1 |
explains how this pest affects the associated animal | 1 |
Describe two stages of the life cycle of the pest from Question 23b).
Reveal Answer
Stage 1: Barber’s pole worm is excreted from sheep in egg form.
Stage 2: These eggs hatch as larvae in the grass.
| Descriptor | Marks |
|---|---|
describes a stage of the pest’s life cycle | 1 |
describes a second stage of the pest’s life cycle | 1 |
Identify the point in the life cycle of the pest from Question 23b) where it is most vulnerable and explain why.
Reveal Answer
The Barber’s pole worm is most vulnerable when its eggs are in the paddock. This is when the eggs can be removed by paddock rotation with a less desirable host animal, which is commonly used to break the worm’s life cycle.
| Descriptor | Marks |
|---|---|
identifies when the pest is most vulnerable | 1 |
explains why the pest is vulnerable | 1 |
The tables show the mulesing practices declared by wool producers for Australian sheep in 2011 and 2021 and the percentage of unsold merino fleeces from mulesed and non-mulesed sheep in 2012 and 2022.
| 2011 | 2021 | |
|---|---|---|
| Practice | % of wool producers | |
| Mulesed without pain relief | 22.0 | 14.5 |
| Mulesed with pain relief | 17.0 | 47.5 |
| Non-mulesed | 5.0 | 12.6 |
| Ceased mulesing | 3.0 | 3.2 |
| Not declared | 53.0 | 22.2 |
| 2012 | 2022 | |
|---|---|---|
| Practice | % of fleeces unsold | |
| Mulesed without pain relief or not declared | 10.2 | 26.3 |
| Mulesed with pain relief | 9.5 | 22.8 |
| Non-mulesed | 7.9 | 18.0 |
Draw two conclusions about the effects of consumer demand on the practice of mulesing in the Australian wool industry. Provide evidence from both tables to justify each conclusion.
Conclusion 1:
Conclusion 2:
Reveal Answer
Conclusion 1: Due to consumer demand, the number of wool producers that mules their sheep is declining. The number of producers that do not mules their sheep increased from 5.0% in 2011 to 12.6% in 2021. Wool from sheep mulesed without pain relief is more likely to be left unsold (26.3% in 2022) compared to wool from non-mulesed sheep (18% in 2022).
Conclusion 2: Where mulesing is still occurring, producers are more likely to use pain relief. In 2011, 17% of producers mulesed their sheep with pain relief, whereas in 2021, 47.5% mulesed their sheep with pain relief. The wool from sheep mulesed with pain relief (22.8% unsold in 2022) was more likely to be sold than wool from sheep mulesed without pain relief (26.3% unsold in 2022).
| Descriptor | Marks |
|---|---|
Draws a conclusion | 1 |
Justifies the conclusion using evidence from the practices table | 1 |
Justifies the conclusion using evidence from the sales table | 1 |
Draws a second conclusion | 1 |
Justifies the second conclusion using evidence from the practices data | 1 |
Justifies the second conclusion using evidence from the sales data | 1 |
In a ruminant animal, fats are broken down into
amino acids.
hydrochloric acid.
volatile fatty acids.
essential fatty acids.
Reveal Answer
amino acids.
Amino acids are the final breakdown products of proteins, not fats.
hydrochloric acid.
Hydrochloric acid is a digestive secretion found in the abomasum (true stomach), not a product resulting from the breakdown of fats.
volatile fatty acids.
Volatile fatty acids (such as acetate, propionate, and butyrate) are primarily the end products of carbohydrate fermentation in the rumen.
essential fatty acids.
Fats (triglycerides) are hydrolyzed by microbial lipases into fatty acids and glycerol; among the choices, this correctly identifies the lipid-derived component.
Fluctuation in the diameter of wool fibres of a purebred merino flock over a calendar year is mainly due to
genetic variation among sheep.
changes in the taste of leaf material.
changes in temperature across the year.
variation in the quality of available pasture.
Reveal Answer
genetic variation among sheep.
Genetics determine the baseline wool characteristics and potential of the sheep, but an individual's genes do not change throughout the year to cause seasonal fluctuations.
changes in the taste of leaf material.
While palatability affects intake, the physical fluctuation in fibre diameter is driven by the nutritional content (protein and energy) available for wool synthesis, not specifically the taste of the leaves.
changes in temperature across the year.
Although temperature varies seasonally, it is not the direct cause of fibre diameter changes; the primary seasonal driver is the impact of seasons on feed availability.
variation in the quality of available pasture.
Wool growth is highly sensitive to nutrition; seasonal variations in the quality and quantity of pasture directly affect the nutrients available to the sheep, causing the fibre diameter to thicken during good feed and thin during poor feed.
A characteristic of an unsustainable biological control method is
a narrow host range for the biological control organism.
an increase in the population of the competing species.
the disappearance of the biological control organism.
a reduction in the population of the targeted pest.
Reveal Answer
a narrow host range for the biological control organism.
A narrow host range is actually a desirable and sustainable characteristic, as it ensures the control agent targets only the specific pest without harming beneficial non-target species.
an increase in the population of the competing species.
An increase in competing species (or the control agent itself) is a natural part of ecological adjustments and does not inherently define the method as unsustainable.
the disappearance of the biological control organism.
A sustainable biological control method relies on the control agent establishing a self-perpetuating population; if the organism disappears, the pest population will rebound, requiring repeated human intervention.
a reduction in the population of the targeted pest.
Reducing the targeted pest population is the primary goal of all biological control methods, whether they are sustainable or not, so this is not a characteristic specific to unsustainability.
The most effective alternative method to mulesing in sheep is
breeding sheep without wool in the breech area.
moving sheep to a new paddock.
vaccinating for diseases.
providing pain relief.
Reveal Answer
breeding sheep without wool in the breech area.
Breeding for bare-breech traits is the most effective long-term alternative because it genetically removes the wool from the area susceptible to flystrike, eliminating the need for surgical modification.
moving sheep to a new paddock.
While pasture management can reduce exposure to flies, it does not address the anatomical susceptibility of the sheep to flystrike caused by wool in the breech area.
vaccinating for diseases.
Vaccination is not a viable alternative because there is currently no commercially available vaccine that effectively prevents flystrike.
providing pain relief.
Providing pain relief improves animal welfare during the mulesing procedure, but it modifies the existing practice rather than serving as an alternative method to it.
Deformed bones were observed in an animal herd. This condition is most likely caused by a deficiency in
iron.
calcium.
nitrogen.
phosphorus.
Reveal Answer
iron.
Iron is essential for the formation of hemoglobin in red blood cells to transport oxygen; a deficiency leads to anemia rather than bone deformities.
calcium.
Calcium is the primary mineral responsible for the hardness and structural integrity of bones. A deficiency prevents proper mineralization, leading to soft, weak, or deformed bones (conditions such as rickets or osteomalacia).
nitrogen.
Nitrogen is a key element in amino acids (proteins) and nucleic acids (DNA/RNA), but it is not a major mineral component responsible for the hardness of the bone matrix.
phosphorus.
While phosphorus is a component of bone mineral (hydroxyapatite), calcium is the most abundant mineral in the skeleton and is the primary answer associated with structural rigidity and preventing deformation in this context.
The table shows average Angus herd EBVs for live weight (kg) from 2015 to 2017.
| Year | Birth | 200 days | 400 days | 600 days |
|---|---|---|---|---|
| 2015 | 4.4 | +15.7 | +28 | +35 |
| 2016 | 4.8 | +17.4 | +35 | +45 |
| 2017 | 5.5 | +23.3 | +41 | +51 |
Determine the change in average 600-day weight from 2015 to 2017.
Reveal Answer
600 days:
| Descriptor | Marks |
|---|---|
provides 16 kg | 1 |
If the data trends in the table continue, draw conclusions about the impact on the Angus breed into the future.
Reveal Answer
The birth weights and live weights of the animals are increasing over time (1.1 kg and 16 kg).
If producers continue to select for animals with higher EBVs, the breed will get heavier into the future.
Higher birth weights may result in greater calving problems.
| Descriptor | Marks |
|---|---|
identifies that birth weights and live weights are increasing | 1 |
predicts that the breed will get heavier | 1 |
concludes that calving problems may occur | 1 |
Barber's pole worm (Haemonchus contortus) is a major parasite in the Queensland sheep industry (particularly where summer rainfall is dominant), with substantial problems associated with drench resistance costing the industry millions of dollars each year. Adult worms live inside the digestive tract of sheep and lay up to 10 000 eggs per day, which are passed in dung. With favourable (warm and moist) weather conditions, infective larvae hatch within 3–4 days and migrate up onto the stalks of pastures. They live within the bottom 7–8 cm of the pasture stalk and are subsequently ingested by grazing sheep, where they mature in the abomasum over 21 days. If they are ingested by grazing cattle or horses, they do not survive, due to differences within the digestive system.
The larvae require warm and moist environments within the lower section of the pasture but are susceptible to direct sunlight and fire, which will kill them.
Individual sheep demonstrate varied resistance to this parasite, with a heritability of worm resistance of at least 25%. Animals that have been exposed to this parasite tend to acquire a basic level of immunity; however, animals that are at greatest risk are weaners, ewes just prior to lambing, as well as those that have never been exposed to the parasite. The parasite causes issues including lethargy, weight loss, a break in the wool staple length, and a drop in milk production. It can also be fatal.
Regular faecal egg counts can give producers information on the current worm burden of their flock as well as that population's resistance to specific drenches. Several drenches are available (including short-acting, quarantine drenches and long-acting drenches); however, Queensland has seen major problems with Barber's pole worm resistance to some drenches. A vaccine has recently been developed, which has been useful in situations where severe drench resistance is evident; however, this vaccine is quite expensive.
Use the PPRR (Prevention, Preparedness, Response, Recovery) model to assess the risk of Barber's pole worm on sheep production. Describe two risk management strategies for each element of the PPRR model for Queensland sheep producers. Provide a justification for each management strategy.
Reveal Answer
Prevention
-
Management strategy 1: Selective breeding for worm resistance: Heritability for this trait is 25%, so, although progress may be slow, creating a herd that has a natural resistance to this parasite will reduce financial loss due to lost productivity in the animals and reduce reliance on drenches.
-
Management strategy 2: Paddock rotation: Rotating the paddocks (ideally every 4 weeks) will help to break the life cycle of the pest, as the hatched larvae will not be ingested by sheep and will eventually die on the pasture as they are unable to complete their life cycle.
Preparedness
- Management strategy 1: Maintain pasture lengths that are longer than 7-8 cm. This will reduce the chance of sheep ingesting the larvae, as they reside on the lower sections of the pasture.
- Management strategy 2: Drench ewes just prior to lambing, as this is the time when they are most susceptible to worm infestations. This will reduce the chance of them getting sick and the chance of their milk production dropping off, which would put the growth of their lambs at risk.
Response
- Management strategy 1: Conduct faecal egg count test to establish the level of infection and to gain information on the most effective type of drench to use.
- Management strategy 2: Put the lambs on a feedlot to stop them from grazing on the ground and picking up larvae.
Recovery
- Management strategy 1: Increase the feed given to affected animals to help them recover the body weight lost due to the infection.
- Management strategy 2: Buy in more ewes to replace the animals that died from the parasite in order to maintain breeding operations.
Identification of strategies for Barber's pole worm
| Descriptor | Marks |
|---|---|
identifies a strategy for prevention | 1 |
identifies a second strategy for prevention | 1 |
identifies a strategy for preparedness | 1 |
identifies a second strategy for preparedness | 1 |
identifies a strategy for response | 1 |
identifies a second strategy for response | 1 |
identifies a strategy for recovery | 1 |
identifies a second strategy for recovery | 1 |
Justification of strategies for Barber's pole worm
| Descriptor | Marks |
|---|---|
justifies a strategy for prevention | 1 |
justifies a second strategy for prevention | 1 |
justifies a strategy for preparedness | 1 |
justifies a second strategy for preparedness | 1 |
justifies a strategy for response | 1 |
justifies a second strategy for response | 1 |
justifies a strategy for recovery | 1 |
justifies a second strategy for recovery | 1 |