animal-related environmental issues that may be controlled by animal management nitrogen phosphorus...
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ANIMAL-RELATED ENVIRONMENTAL ISSUES THAT MAY BE CONTROLLED
BY ANIMAL MANAGEMENT• Nitrogen• Phosphorus• Odors• Greenhouse gases• Sediment• Species diversity
TOOLS TO MANAGE ANIMAL-RELATED ENVIRONMENTAL ISSUES
• Nutritional management• Managed grazing
CONTROLLING NITROGEN EXCRETION BY OPTIMIZING PROTEIN METABOLISM
Monogastrics• Increase protein digestibility• Lower crude protein intake• Dietary balance
– Protein:energy ratio– Balance of essential amino acids
• Phenyalanine• Valine• Tryptophan• Threonine• Isoleucine• Methionine• Histidine• Arginine• Leucine• Lysine
• Increase protein digestibility
• Decrease N intake• Decrease protein
degradability• Diet balance
– Carbohydrate energy
– Sulfur
– Phosphorus
Protein
Protein
Degraded
Escape
NH3Microbialprotein
Convertedto urea inliver
MetabolizableProtein
ABSORBED
Excreted
NPN
CONTROLLING NITROGEN EXCRETION BY OPTIMIZING PROTEIN METABOLISM
Ruminants
MANAGING NITROGEN EXCRETION BY DAIRY COWS100 cow herd
Crude protein, % 21.3 17.1 17.1
Protein supplement
Soybean meal
Soybean meal Heat-treated soybean meal
Milk production, lb/day
89.8 83.1 88.9
Feed cost, $/cow 3.88 3.62 3.64
N excretion, lb/yr
Urinary 25,487 17,914 16,366
Fecal 17,597 17,740 17,721
Total 43,085 35,654 34,087
• Lower P intake– Phase feeding
• Feed phytase to monogastrics– 50% of the phosphorus in most feeds is bound to phytic
acid
• Feed low phytate corn and soybeans to monogastrics
• Dietary balance– Ca:P ratio– Vitamin D metabolites
CONTROLLING PHOSPHORUS EXCRETION BY OPTIMIZING NUTRITION
MANAGING PHOSPHORUS EXCRETION BY DAIRY COWS
100 cow herd
P concentration, %
.45 .39 .36
Milk production, lb/cow
89.8 90.3 90.6
$/cow 3.88 3.85 3.83
Excreted, lb/yr
Urinary 118 108 102
Fecal 4,540 3,565 2,992
Total 4,658 3,673 3,094
P balance, g/day +10 -1 -7
GREENHOUSE GASES
• Carbon dioxide
• Methane (CH4)
– 21 x the greenhouse effects of CO2
• Nitrous oxide– 310 x the greenhouse effects of CO2
SOURCE STRENGTHS OF GHG EMISSIONS FROM DIFFERENT BEEF AND DAIRY
OPERATIONS
U.S. Beef cow-feedlot
CA Dairy Wis Dairy NZ Grazing-based Dairy
kg carbon dioxide equivalent/kg product
Enteric methane
5.5 .36 .41 .60
Manure methane
.14 .21 .03 .04
Nitrous oxide
8.1 .37 .42 .76
Carbon dioxide
1.8 .33 .57 .22
Total GHG 15.5 1.26 1.38 1.62
WHY IS METHANE PRODUCED?
Carbohydrates
Microbialenergy Acetate
H+ hhhhhhh
CH4
Propionate Other electron acceptors (Unsaturated fattu acids)
CONTROLLING METHANE PRODUCTION BY RUMINANTS THROUGH DIET MANAGEMENT
• Increase the proportion of grain and decrease the proportion of forage in the diet– Must have a minimum of 50% forage in dairy diets and
10% in feedlot diets
• Grind forage• Feed ionophores
– Monensin– Lasalocid– Salinomycin
• Feed unsaturated fatty acids– Maximum 5% of diet dry matter
EFFECTS OF GRAZING ON ENVIRONMENTAL QUALITY
• Well-managed grazing– Optimize forage productivity
and nutritional quality– Maximize forage species
diversity– Improve efficiency of forage
utilization– Maintains forage cover on
streambanks– Minimize soil erosion– Minimize P loading of
streams– Minimize soil compaction
and trailing– Maximize manure nutrient
distribution
• Poorly managed grazing– Reduced forage
productivity and quality– Minimize forage species
diversity– Weed infestation– Loss of streambank cover– Stream widening and loss
of aquatic habitat– Increased soil erosion– Increased P loading of
streams– Increased soil compaction– Increased cow paths– Poor manure distribution
KEY TO SUSTAINABILITY OF GRAZING LANDS
• Managing vegetative cover through– Feed for grazing livestock
– Hold soil into place
– Filter water
– Recycle nutrients
EFFECTS OF FORAGE CANOPY HEIGHT ON GROUND COVER, INFILTRATION RATE, AND EROSION RATE
AFTER TREADING AT THREE RATES ON A NEW ZEALAND HILL COUNTRY PASTURE
Canopy height, inches
0 1 2 30
20
40
60
80
100Bare ground, % Infiltration rate, l/sq m/hr Sediment loss, g/sq m/hr
COMPONENTS OF GOOD GRAZING MANAGEMENT
• Appropriate stocking rate– Neither too low or high– Flexible management to maintain forage quality
• Adjust stocking rate• Hay harvest
• Appropriate rest periods– Based on forage growth rate
• 15 days early summer• 35 days in mid-summer
• Appropriate design– Number of paddocks
• 8 – 12 for rest• 24 – 36 for grazing efficiency
– Square paddocks– Water in each paddock
CALCULATING THE LENGTH OF OCCUPANCY FOR PADDOCKS
• Estimate forage yield• Estimate total forage in 5
ac paddock• Estimate available forage
in paddock• Estimate forage intake by
fifty 1250 lb cow-calf pairs• Calculate days/paddock• Calculate total paddocks
• Calculate total acres
• 15 cm x 110 lb/ac/cm = 1650 lb/ac• 1650 lb/ac x 10 ac = 16,500 lb
• 16,500 lb x 50% = 8250 lb
• 50 x 1250 x 3.5% BW = 2188 lb/day
• 8250 lb/pad / 2188 lb/day = 3.8 days• 35 days rest/3.8 days + 1 = 10.2
paddocks• 10.2 paddocks x 10 ac/pad = 100 ac
Months
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
To
tal
fora
ge
ma
ss
, lb
/ac
re
0
1000
2000
3000
Cool season grassLegumesWarm season grassStockpiled gr-leg (Hay equiv.)Corn stalks (Hay equiv.)
FORAGE AVAILABILITY THROUGHOUT THE YEAR
ARRANGEMENT OF TREATMENTS(June, 2002)
MEASUREMENT OF SEDIMENT AND PHOSPHORUS LOSSES
Rainfall simulations• Frequency
– June, August, October, and April
• Locations– 3 in 2 slope classes within
each paddock– 3 in each buffer strip at
paddock base– 3 in each buffer strip 30 ft
from paddock base
• Rainfall rate– 2.8 inches/hour
• Duration– 1.5 hours
EFFECTS OF FORAGE TREATMENTS ON ANNUAL SEDIMENT FLOW
(Year 1)
Grazing treatment
Se
dim
en
tati
on
, lb
/ac
.
0
10
20
30
40
50
60
70Ungrazed Hay/stockpile 2" Continuous 2" Rotational 4" Rotational
a
b
b b
b
Total P Soluble P
lb/a
c
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35Ungrazed Hay/stockpile 2" Continuous 2" Rotational 4" Rotational
a
b
bb
b
bb
a
c
c
EFFECTS OF FORAGE TREATMENTS ON ANNUAL TOTAL AND SOLUBLE PHOSPHORUS FLOW
(Year 1)