Digestive System Ruminants

The only way of finding the limits of the possible is by going beyond them into the impossible. Arthur C. Clarke

Dentition - Cattle Incisors Pre-molars Molars Deciduous: 20 (there are no deciduous molar and deciduous PM1) (I C PM) Permanent: 32 (No PM1)

Eruption – Deciduous Teeth TeethAge at eruption 1 st Incisor (Di 1)Birth – 2 weeks 2 nd Incisor (Di 2)Birth – 2 weeks 3 rd Incisor (Di 3)Birth – 2 weeks 4 th Incisor (Di 4 or C)Birth – 2 weeks 1 st Cheek Tooth (Dp 2)Birth to few days of age 2 nd Cheek Tooth (Dp 3)Birth to few days of age 3 rd Cheek Tooth (Dp 4)Birth to few days of age

Deciduous Permanent

Eruption – Permanent teeth TeethAge at eruption I 118 – 24 months I 224 – 30 months I 336 months I4 or C42 – 48 months 1 st cheek tooth P224 – 30 months P3 second cheek tooth18 – 30 months P4 third cheek tooth30 – 36 months M2 fifth cheek tooth24 – 30 months M3 sixth cheek tooth24 – 30 months

Cattle - Dentition 14 months:14 months –complete deciduous –short and broad –bright ivory color –space between Di 1 incisors

How old? Teeth are longer and narrower Not touching at upper corner RostralRostral - lateral

How old? Eruption of one or more central incisors

How old? At least one of 2 nd pair of incisors

How old? I3: 36 months, I4: 42 months Peg teeth

Dentition – Sheep and Goats 2 (0/4 incisors, 3/3 pre-molars, 3/3 molars) = 32 Animal under one year old: no permanent teeth One year old (2 permanent teeth) Two years old (4 permanent teeth) Three years old (6 permanent teeth) Four years old (8 permanent teeth) Old animal, more than four years old

Permanent Tooth Eruption Incisor (I1)1-1.5 years Incisor (I2)1.5-2 years Incisor (I3)2.5-3 years Incisor (I4)3.5-4 years Premolars1.5-2 years Molar (M1)3 months Molar (M2)9-12 months Molar (M3)1.5-2 years

How old- Sheep? Wide spacing Broken mouth

How old - Goats Deciduous – 2 weeks Deciduous – 10 months 1.5 – 2 yrs 3 yrs 10 yrs

Digestive System Cranial fermentors –Forestomach –E.g. cattle, sheep and deer –digest and extract energy from cellulose –utilize the protein from fermentative microbes Caudal fermentors Cecal digestors E.g. horses and rabbits digest and extract energy from cellulose utilize dietary hexose sources directly

Digestive system calf Esophageal groove –first few weeks of life, the rumen, reticulum, and omasum are undeveloped –By pass reticulum and rumen and goes directly into abomasum –Grain and forage for rumen development ~ 3 weeks age

Fermentation Ecology Rumen inoculation –1 ml of rumen content: ~10 to 50 billion bacteria,1 million protozoa, variable numbers of yeasts and fungi –Cellulolytic (digest cellulose) –Hemicellulolytic (digest hemicellulose) –Amylolytic (digest starch) –Proteolytic (digest proteins) –Sugar utilizing (utilize monosaccharides and disaccharides) –Acid utilizing (utilize such substrates as lactic, succinic and malic acids) –Ammonia producers –Vitamin synthesizers: vitamin B and K –Methane producers

Entodinium (Rumen Protozoa)

Symbiotic Relationship Microbes provide to the ruminant –Digestion of cellulose and hemicellulose –Provision of high quality protein –Production of VFA –Provision of B vitamins –Detoxification of toxic compounds Ruminants provide to microbes –Housing –Garbage removal –Nutrients –Optimal environment for growth

Fermentation Ecology Rumen pH between 6 and 7 Grain engorgement: pH <5.5 – protozoal populations decrease Products: Sugars -> VFA’s –acetic, propionic and butyric acids

Volatile Fatty Acids Acetic acid –is utilized minimally in the liver –oxidized throughout most of the body to generate ATP –Major source of acetyl CoA for synthesis of lipids. Proprionic acid –is almost completely removed from portal blood by the liver –In the liver, proprionate serves as a major substrate for gluconeogenesis, which is absolutely critical to the ruminant because almost no glucose reaches the small intestine for absorption. Butyric acid, –most of which comes out of the rumen as the ketone beta-hydroxybutyric acid –is oxidized in many tissues for energy production.

Ruminant Anatomy the rumen or paunch reticulum or "honeycomb," the omasum or “book," the abomasum or "true stomach." Esophagus > reticulum > rumen > omasum > abomasum CD

Reticulum – ‘honeycomb’ Lies against the diaphragm rumino-reticulum connected by tissue Heavy objects fall –Hardware disease (traumatic reticuloperitonitis) No enzyme secretion Formation of food bolus

Rumen – ‘Paunch’ largest of the forestomaches sacculated by muscular pillars: dorsal, ventral, caudodorsal and caudoventral sacs stratified squamous epithelium (Papillae lining) fermentation vat (25 gallons, anaerobic bacteria) Absorbs most VFA Healthy cows: 1-2 minutes/contractions

Omasum - book broad longitudinal folds or leaves Absorption of water Reduce particle size, ingesta between the leaves will be drier than in other compartments

Abomasum – true stomach –This is the only compartment (also called the true stomach) with a glandular lining –HCL and digestive enzymes (proteolytic enzymens: mucin, pepsinogen, renin, lipase), needed for the breakdown of feeds, are secreted into the abomasum –PH decreases from 6 > 2.5 Denatures proteins Kills bacteria and pathogens Dissolves minerals

Digestive system - Ruminants The small intestine –measures about 20 times the length of the animal –duodenum, jejunum, and ileum. –secretions of the pancreas and the gallbladder, which aid digestion –Most of the digestive process is completed here, and many nutrients are absorbed through the villi (small finger-like projections) into the blood and lymphatic systems. Cecum –junction of the SI and LI, where some previously undigested fiber may be broken down –Function of cecum? Large intestine –last segment of the tract through which undigested feedstuffs pass –absorption of water is the primary digestive activity occurring in the large intestine –Some bacterial digestion of undigested feed occurs

Function of digestive tract Eructation (belching) –Large quantities of gas, mostly carbon dioxide and methane, are produced in the rumen Rumination (4 phases) –35 to 40 percent of each day ruminating (cud chewing) –During rest periods, feed boluses (cud) are regurgitated for rechewing to reduce particle size and for resalivation. –Feed is more readily digested by rumen microbes as particle size is reduced –Redeglutition: swallowing

Four Steps of Rumination Regurgitation –Reverse peristalsis carries food to mouth Remastication –Liquid squeezed from bolus and swallowed –Bolus chewed Reinsalivation –Adding more saliva Redeglutition –Swallowing bolus and liquids

Remastication and Redeglutition

Digestive system - Ruminants Motility of the rumen and reticulum –contractions mix the rumen contents, bring microbes in contact with new feedstuffs, reduce flotation of solids, and move materials out of the rumen Saliva production –50 to 80 quarts of saliva –provides liquid for the microbial population, recirculates nitrogen and minerals, and buffers the rumen –buffer for helping to maintain a rumen pH between 6.2 and 6.8 for optimum digestion of forages and feedstuffs Vomiting –Rare: suspect toxins

References Large Animal Clinical Procedures, Elizabeth Hanie /herbivores/index.htmlhttp:// /herbivores/index.html ms/components/di htmlhttp:// ms/components/di html faculty.fortlewis.edu/LASHELL_B/Nutr2- Rumdigestion.pdf extension/dairy/nutrition/calves/rumenhttp:// extension/dairy/nutrition/calves/rumen