Ruminant pt 4 Flashcards
What are the characteristics of group I saliva?
Isotonic, strongly buffered, and produced continuously (Parotid, inferior molar, palatine, pharyngeal and buccal)
What are the characteristics of Group II saliva?
Hypotonic, weakly buffered, and is produced mainly during feeding (Submaxillary, sublingual and labial)
What is the chemical composition of saliva?
pH 8.5
Dry matter 1.4%
Ash 0.1%
Nitrogen (mostly urea) 0.1-0.2%
What are the buffering compounds found in saliva?
Mostly bicarb but also phosphate
How much saliva is secreted?
Sheep: 6-10L
Cows: 50-200
What factors effect parotid saliva secretion?
Ruminating and diet type
What factor effects submaxillary saliva secretion?
Eating and diet type
What is the function of saliva?
- Lubrication and taste
- Enzyme activity
- Source of nutrients for ruminal microorganisms
- Influence nutrient removal from rumen
- Antifoaming agent
- Convey antibodies
- Buffering
How can you collect ruminal contents?
- Stomach tube
- Ruminal cannula
- Rumenocentesis
What is the otpimal ruminal pH?
6.8
What microbe has the largest pH range it can survive in?
Bacteria
What is the highest pH that microbes in the rumen can survive in?
7.5
How is ruminal pH regulated?
- Feed stuffs: mineral compounds
- Salivary compounds: bicarb and phosphates
- Fermentation products: VFA, lactate, and ammonia
When do we need to enhance ruminal buffering capacity?
Need this if diet does not provoke much saliva.
- Don’t require much mastication/rumination
- High moisture content
- Diets that contain acids or generate more acids
How do you enhance ruminal buffering capacity?
- Diets that produce less acid and or have high buffering capacity
- Stimulate secretion by salivary glands
- Dietary supplementation of buffers
What is a buffer?
Compounds used in cattle diets to increase buffering capacity in rumen and maintain pH
Why do we feed buffers to dairy cattle?
Prevent ruminal acidosis and improve milk fat content
When are buffers the greatest benefit to feedlot cattle?
- During step up to high grain diets
- When rapidly fermentable grains are fed (wheat or barley)
- Processed grains
- When switched from forage to concentrate diets
When are buffers at the greatest benefit for dairy cows?
- Early lactation
- When feeding storage
- Small sized food
- Abruptly switching food type
- Milk fat test is low
What are the types of reticulo-rumenal motility?
- Primary or mixing cycle: Peristalsis
2. Secondary or eructation cycle: antiperistalsis
What are specialized contractions in the reticulo-rumen?
- Reticular groove
2. Extrareticular contraction during rumination
What is the set of contractions in the primary cycle?
Reticulum-> Cranial sac-> Dorsal sac-> Dorsal blind sac-> Ventral sac-> Ventral blind sac
What are secondary contractions?
- Independent of reticular contraction
- Associated with eructation
- Involves dorsal, dorsal blind, and ventral sac
- Antiperistalsis
What is the frequency of ruminal motility?
1 per minute
