Lecture 15 - Pasture Bloat Management and Plant Winter Survival

Question 1

can pure alfalfa be grazed
how about alfalfa hay

Answer 1

no
yes

Question 2

pasture bloat

Answer 2

is a common digestive disorder of ruminants (cannot release rumen gas)

Question 3

4 compartments of a ruminant stomach

Answer 3

rumen
reticulum
omasum
abomasum

Question 4

other names for pasture bloat

Answer 4

frothy or primary bloat

Question 5

symptoms of bloat

Answer 5

• severe abdominal distension
• respiratory distress
• animal collapses

Question 6

what forages cause pasture bloat

Answer 6

alfalfa, white clover, sweet clover, annual clovers

Question 7

what forages dont cause pasture bloat

Answer 7

cicer milkvetch, sainfoin

Question 8

causes of frothy bloat

Answer 8

• rapidly digested feed with high protein
• small particles (chloroplast)
• increased microbial activity
• animal genetic/physiological state

Question 9

breeding goal of alfalfa

Answer 9

development of alfalfa with low initial rate of digestion

Question 10

forage mixtures target alfalfa:grasses ratio is

Answer 10

15% alfalfa 85% grasses (by weight)

Question 11

what is a problem with grasses in forage mixtures during the summer

Answer 11

slower regrowth in the summer

Question 12

use of CT containing legume

Answer 12

need more than 10% sainfoin to prevent most deaths

Question 13

problems with the use of CT containing legume

Answer 13

slow regrowth of sainfoin and less sainfoin as stands age

Question 14

the safe growth stage for alfalfa

Answer 14

full bloom stage

Question 15

swathing and wilting of alfalfa

Answer 15

• alfalfa hay seldom cause bloat
• wilting for 24hrs increases sulfhydryl content of alfalfa proteins

Question 16

_____ hrs of wilting alfalfa reduced bloat incidence to 0

Answer 16

48

Question 17

forms of bloat management additives

Answer 17

feed or water additives

Question 18

bloat management grazing practices

Answer 18

• limit grazing period during first few days to give rumen micro-flora time to adjust to legume
• avoid early morning or evening grazing
• cull frequent bloater

Question 19

best forage for cold hardiness and temp it can tolerate

Answer 19

alfalfa, -22 C

Question 20

climatic conditions related to winter injury

Answer 20

• low temp
• lack of snow cover
• alternate freezing and thawing cycles of soil
• fast freezing causing ice crystals to form inside
• slow freezing, where ice forms outside cell membrane
• ice sheets

Question 21

root heaving (alfalfa)

Answer 21

freeze and thaw of soil pushes roots from the ground

Question 22

what stand age of alfalfa is the most critical age for assessment of winter hardiness

Answer 22

3rd winter

Question 23

changes at cellular and molecular levels during hardening process

Answer 23

• decrease in total water
• increase in sugar content (antifreeze)
• increase in organic constituents
• increase permeability of cell membrane

Question 24

plant morphologcial and physiological aspects affecting winter survival

Answer 24

• stand age
• stage
• location of crown tissue
• disease presence
• high levels of root reserves

Question 25

management to avoid winter killing

Answer 25

- winter hardy species - grass legume species - leave stubble to capture snow - fertilization - critical rest period for alfalfa