1. INTRODUCTION TO THE PRODUCTION SECTOR OF THE MEAT INDUSTRY PT. 2

Does the body and carcass composition of animals change with growth?

Yes, it changes considerably both prior to birth (prenatal growth) and after birth (postnatal growth).

What is illustrated in Figure 2.4?

Drawings of the same Southdown ram at four different growth stages from 6.2 kg at 1 week to 60.1 kg at 15 months.

What happens to the head relative to the whole body as an animal grows?

The head becomes relatively smaller.

How do the size and weight of the feet and bones change as an animal matures?

They become larger and heavier.

What happens to the 'blockiness' or 'depth' of the body as the animal grows?

It increases.

What shape does the growth curve of mammals typically follow?

An 'S'-shaped or sigmoid curve.

What does the initial period of the growth curve represent?

A period when the growth rate is increasing, mostly before birth.

What is the 'finished' weight of animals raised for meat production?

Usually about two-thirds to three-quarters of the animal's mature weight.

What factors affect the growth pattern of livestock?

Seasonal changes in feed supply and environmental conditions.

What is the significance of the inflexion point in a growth curve?

It indicates the maximum average daily gain (ADG) before growth rate begins to decline.

What happens to growth efficiency before the inflexion point?

It is generally increasing.

What occurs to growth efficiency beyond the inflexion point?

It typically declines.

What are the key changes in composition during post-natal growth?

Changes in muscle, fat, and bone composition.

How does prenatal growth affect postnatal muscle growth?

The number of muscle fibers is largely set before birth, limiting overall muscle size.

What does Figure 2.6 illustrate?

The way nine different characteristics change with increasing carcass weight for beef-type steers.

What is an early maturing weight characteristic?

One that increases at a decreasing rate as carcass weight increases.

What indicates a percentage or ratio is early maturing?

It decreases as carcass weight increases.

What is the typical range of carcass weights for steers in NZ?

250 to 350 kg.

What influences the growth of important body tissues such as muscle?

Factors occurring before birth.

What is the implication of having a limited number of muscle fibers at birth?

It limits the overall size of the muscle.

What does a smooth growth curve indicate?

It reflects optimal growth conditions without environmental fluctuations.

What is the relationship between growth rate and environmental conditions?

Growth rate can vary significantly with changes in environmental conditions.

What is the significance of understanding growth patterns?

It enables more accurate assessments of potential animal growth under good feeding conditions.

What type of analysis reveals changes in body composition during growth?

Chemical analysis or dissection of the body into its parts.

What happens to the carcass composition as animals grow older?

The proportions of muscle, fat, and bone change, often following predictable patterns.

What is the effect of a changing environment on livestock growth?

It can disrupt the smooth growth curve typically expected under constant conditions.

What is the role of feed quality in animal growth?

Adequate quantities of good quality diet are essential for optimal growth.

What are the three main components of carcass composition?

Fat, Bone, and Lean (Muscle)

How does fat percentage change with increasing carcass weight?

Fat % increases at an increasing rate.

What happens to the proportion of total muscle in the distal parts of the legs as an animal grows?

It decreases, while the abdominal muscles become a larger proportion.

What is the significance of subcutaneous fat depth in animals?

It provides a good indication of overall fatness.

What are the four main functions of the skeletal system?

1. Structural framework for muscles, 2. Protection of organs, 3. Storage of calcium and phosphorus, 4. Production of blood cells.

What role does bone marrow play in the skeletal system?

It is the main site of production of new blood cells.

What is the composition of bone from immature growing animals?

About one third water, one third ash (mainly calcium and phosphate), one quarter protein (mainly collagen), and the remainder fat and other components.

How does the structure of bone compare to reinforced concrete?

The collagen framework is like flexible reinforcing steel, while the bone salts are comparable to hard, inflexible concrete.

What is the relationship between muscle and bone as an animal matures?

The animal becomes more 'blocky' and 'compact' as muscle and fat layers increase relative to bone length.

What is meant by 'waves of growth' in animal development?

It refers to the sequential maturation of tissues: nervous tissue, bone, muscle, and finally fat.

What happens to daily feed intake as an animal approaches maturity?

It increases to a maximum and then usually declines, fluctuating seasonally thereafter.

What is the effect of carcass weight on the proportion of total muscle in expensive cuts?

It tends to decrease slightly as carcass weight increases.

What are ligaments and how do they differ from tendons?

Ligaments are connective tissues that connect bone to bone, while tendons connect muscle to bone.

What is the role of synovial membranes and fluid in the skeletal system?

They facilitate the movement of joints.

What is the significance of the 'goodness-of-fit' for the line in carcass weight analysis?

It indicates how well the data fits the expected pattern of change.

What does the term 'dressing-out %' refer to?

It refers to the percentage of the animal's live weight that is converted into carcass weight.

How does the proportion of total fat change as an animal matures?

The proportion of fat in the subcutaneous depot increases, indicating it is late-maturing.

What is the impact of growth on the shape of animals?

Animals become more 'blocky' and 'compact' due to increased muscle and fat thickness relative to bone length.

What are the main components of the skeletal system?

Bones, cartilage, synovial membranes, synovial fluid, and ligaments.

What happens to gut contents percentage as an animal grows?

It changes as the animal matures, affecting overall carcass composition.

What is the importance of understanding bone structure in relation to meat production?

It helps in appreciating how bones affect live animal well-being, meat yield, and meat quality.

What is the relationship between bone and muscle in terms of skeletal function?

Muscles depend on skeletal attachments to function properly.

What is the significance of the 'early' and 'late' maturing classifications in carcass composition?

They indicate how different tissues develop and mature at varying rates.

How does the composition of bone affect its function?

The specific job of each bone and the stresses it endures determine its shape and internal structure.

What does the term 'M:B' refer to in carcass analysis?

It refers to the ratio of muscle to bone in the carcass.

What is the typical pattern of change for nervous tissue, bone, muscle, and fat during growth?

Nervous tissue matures first, followed by bone, muscle, and finally fat.

What are the two main parts of a long bone?

The epiphyses at either end and the diaphysis (shaft) in the middle.

What covers the smooth areas at the ends of a long bone?

Articular cartilage.

Where does growth in bone length primarily occur?

At the epiphysial plate.

What is the periosteum?

A thin layer covering the whole bone where overall bone growth takes place.

What are the two types of internal bone structure?

Spongy bone (where stresses are low) and dense bone (where more strength is needed).

What is contained within the femur?

Bone marrow.

To which bone is the femur attached at its proximal end?

The pelvic bone.

To which bone is the femur attached at its distal end?

The tibia.

What is the typical number of cervical vertebrae in mammals?

7 cervical vertebrae.

How many thoracic vertebrae does a horse have?

18 thoracic vertebrae.

How many lumbar vertebrae does a cow have?

6 lumbar vertebrae.

What is the role of the skull in the skeleton?

It is fused together to form the head bones, except for the lower jaw and a small bone in the tongue.

What is the function of the rib cage?

It protects the thoracic organs and is composed of ribs that correspond to thoracic vertebrae.

What bones make up the forelimb?

Scapula, humerus, radius, ulna, carpal bones, metacarpal, and phalangeal bones.

What is the patella commonly known as?

The knee bone.

What is the significance of the skeletal system in the meat industry?

It is important for carcass classification and assessing the yield of lean meat.

What happens to carcasses with excessively high levels of bone relative to muscle?

They are penalized in carcass classification systems.

What is the economic value of bone in the meat industry?

Generally low; it is often used for blood and bone fertilizer or as a calcium supplement.

What is the USDA's grading system for beef carcass maturity?

It has five levels (A to E) based on skeletal characteristics.

What characterizes an A maturity carcass in terms of skeletal features?

Soft porous chine bones, somewhat narrow and red rib bones, distinct separation of sacral vertebrae, and presence of cartilage on the split aitch bone.

What is the function of the olecranon?

It is the elbow.

What is 'hip-hanging' in the meat industry?

A method of hanging carcasses that stretches muscles for improved tenderness.

What is the role of the tuber coxae?

It is the hip bone that becomes apparent for animals in poor condition.

What is the tuber ischii?

The pin bone beside the tail.

What is the tuber calcis?

The point on a tarsal bone where the achilles tendon is attached.

What are the bones of the hind limb?

Hip bone, femur, tibia, tarsal bones, metatarsal, and foot bones.

What is the significance of the number of ribs in relation to thoracic vertebrae?

There is always the same number of ribs as thoracic vertebrae.

What are the characteristics of E-maturity carcasses?

They have hard white chine bones, little or no cartilage, broad white ribs, and sacral vertebrae that may be difficult to distinguish.

What is the purpose of the skeletal system in evaluating animal composition?

It provides landmarks that assist in condition-scoring systems for sheep and cattle.

Where are the common sites for assessing fatness in sheep?

At the GR site over the ribs and in the loin region.

What is the general procedure for assessing the fatness of an animal?

Look at areas with little muscle between the skin and the bone to minimize confusion between fat and muscle thickness.

What areas are assessed for good muscling in animals?

Areas where there is little fat relative to muscle between the skin and the bone.

What type of muscle is primarily discussed in this section?

Skeletal muscle, also known as voluntary or striated muscle.

What are the main functions of skeletal muscle?

To bring about movement, produce heat, and serve as a source of nutrients in emergencies.

How does skeletal muscle achieve movement?

Through contraction in conjunction with bones that provide a system of levers.

What is the role of ATP in muscle contraction?

ATP provides energy for contraction and maintains the sliding of thick and thin filaments.

What happens during muscle contraction at the sarcomere level?

The Z discs come closer together while the lengths of thick and thin filaments remain unchanged.

What is the sliding-filament mechanism?

It describes how thick filaments slide relative to thin filaments during muscle contraction.

What initiates muscle contraction?

The release of calcium from the sarcoplasmic reticulum triggered by a nerve impulse.

What is the structure of skeletal muscle composed of?

Muscle fibers grouped in bundles held together by connective tissue.

What is the significance of the sarcomere in muscle contraction?

It is the basic unit of muscle contraction, measuring the distance between adjacent Z-lines.

What is the effect of muscle contraction on sarcomere length?

The sarcomere shortens from a length of 3.0 µm to 1.6 µm during contraction.

What is the relationship between ATP and muscle plasticity?

ATP maintains plasticity, allowing thick and thin filaments to slide easily relative to each other.

What are the two crucial functions of ATP in skeletal muscle?

To provide energy for muscle contraction and to maintain filament sliding.

What is the role of calcium ions in muscle contraction?

Calcium ions are released from the sarcoplasmic reticulum to initiate contraction.

What is the composition of muscle fibers?

Muscle fibers are made up of myofibrils, which contain thick and thin filaments.

What is the function of connective tissue in muscle structure?

It holds together muscle fibers and bundles, contributing to the overall structure of the muscle.