Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Identify common pasture species in South Africa.
• Explain the principles of rotational grazing.
• Calculate the carrying capacity of a pasture.
• Describe methods of fodder conservation like haymaking and silage.

Lesson summary

This week, we delve into the crucial area of pasture and fodder production, a cornerstone of successful livestock farming in South Africa. Quality pasture and fodder are essential for healthy livestock, efficient production, and ultimately, a profitable farming operation. In a country like South Africa, where grazing land can be affected by drought and variable rainfall, understanding how to manage pasture effectively and supplement with fodder becomes even more critical. Poor pasture management leads to overgrazing, soil degradation, and reduced livestock productivity, impacting food security and the livelihoods of many rural communities.

Lesson notes

2. 1. Pasture Grass and Legume Species in South Africa: South Africa boasts diverse pasturelands, and selecting the right species is vital.

Consider these factors: climate (rainfall, temperature), soil type, livestock type (cattle, sheep, goats), and desired productivity.

Grasses: Themeda triandra (Red Grass): A palatable, perennial grass, dominant in many natural grasslands. Well-suited to less intensive grazing systems.

Cenchrus ciliaris (Buffel Grass): Drought-resistant, suitable for arid and semi-arid regions. Introduced species, can be invasive.

Eragrostis curvula (Weeping Lovegrass): Widely adapted, used for erosion control and grazing. Can become unpalatable if mature.

Panicum maximum (Guinea Grass): High-yielding, requires good rainfall or irrigation. Excellent for intensive grazing.

Digitaria eriantha (Smuts Finger Grass): Palatable, good for haymaking. Sensitive to frost.

Legumes: Medicago sativa (Lucerne/Alfalfa): High-protein, excellent fodder crop. Requires well-drained soils and specific soil p

H. Trifolium repens (White Clover): Low-growing, improves soil fertility (nitrogen fixation). Tolerant to grazing.

Stylosanthes guianensis (Stylo): Tropical legume, drought-tolerant, suitable for warmer regions. 2.

2. Rotational Grazing: Rotational grazing involves dividing a pasture into paddocks and moving livestock between them on a planned schedule. This allows pasture plants to recover and prevents overgrazing.

Benefits: Improved Pasture Health: Plants have time to regrow, increasing biomass production.

Reduced Soil Erosion: Healthy plant cover protects the soil from wind and water erosion.

Increased Livestock Productivity: Livestock have access to fresh, high-quality forage.

Weed Control: Grazing can help control certain weed species.

Parasite Control: Breaking the life cycle of internal parasites by moving livestock to clean paddocks.

Example: A farmer has 10 hectares of pasture and 20 cattle. He divides the pasture into 4 paddocks of 2.5 hectares each. He rotates the cattle every 7 days, giving each paddock 21 days to recover. 2.

3. Carrying Capacity: Carrying capacity refers to the number of livestock that a given area of pasture can support sustainably without causing degradation. It's influenced by pasture yield, animal size, and grazing period.

Calculation: Carrying Capacity (Animals/Hectare) = (Total Forage Production (kg/ha) x Utilisation Rate) / (Animal's Daily Forage Requirement (kg) x Grazing Period (days))

Forage Production: Estimate based on pasture surveys or historical data.

Utilisation Rate: The percentage of forage that animals consume (typically 50-70%).

Animal's Daily Forage Requirement: Depends on animal type, size, and physiological state (e.g., lactating cows need more).

Example: A pasture produces 5000 kg of forage per hectare. The utilisation rate is 60%. A cow requires 10 kg of forage per day, and the grazing period is 365 days. Carrying Capacity = (5000 kg/ha 0.60) / (10 kg/day 365 days) = 0.82 animals/hectare This means the pasture can sustainably support 0.82 cows per hectare. To avoid overgrazing, the farmer should stock at or below this level. 2.

4. Fodder Conservation: Haymaking and Silage Production: When pasture production is seasonal (e.g., during the rainy season), conserving excess forage as hay or silage ensures livestock have feed during the dry season.

Haymaking: Drying forage to a low moisture content (around 15%) to prevent spoilage.

Steps: Cutting: Mowing the forage at the correct stage of maturity (before seed heads form).

Curing: Drying the forage in the sun, turning it regularly to ensure even drying.

Baling: Compressing the dried forage into bales for storage.

Storage: Storing bales in a dry, well-ventilated place to prevent mold growth.

Silage Production: Fermenting moist forage in the absence of oxygen. This produces lactic acid, which preserves the forage.

Steps: Chopping: Cutting the forage into small pieces to facilitate compaction.

Ensiling: Packing the chopped forage tightly into a silo or bunker to exclude air.

Sealing: Covering the silo or bunker with plastic to prevent air and water infiltration.

Fermentation: Allowing the forage to ferment for several weeks. Lactic acid bacteria convert sugars into lactic acid, preserving the feed. 2.

5. Nutritional Value of Fodder Crops: Different fodder crops have varying nutritional content.

Key nutrients: Crude Protein (CP): Essential for growth, reproduction, and milk production. Legumes (lucerne, clover) are generally high in C

P. Energy (Total Digestible Nutrients - TDN): Provides energy for maintenance, activity, and production. Grasses are generally good sources of energy. Fibre (Neutral Detergent Fibre - NDF, Acid Detergent Fibre - ADF): Affects digestibility and intake. High-fibre forages are less digestible.

Minerals and Vitamins: Essential for various metabolic functions. Supplementation may be necessary if fodder is deficient.