Advanced Ruminant Nutrition

What is the order of importance of main nutrients for dairy cows?

DMI

Energy (CHO and fats)

Protein

Fiber

Macrominerals

Trace Elements

Roughly half of all utilizable protein in a diary cow comes from

Digestion of microbes from rumen

What is the most important nutritional factor for maintaining health status of cows (dry or lactating)?

Ad lib feed

When are dairy cows in an energy defecit nutritionally?

Day 0 to ~50 post partum (early lactation)

What occurs in dairy cows in terms of DMI around calving?

Sharp decline and a slow return to their “normal” over 50-60 days

Every time you mix cow groups, you will see a

decrease in DMI for 2-3 days

What will a higher DMI allow in dairy cows?

Higher performance, lower nutrient density rations, increase use of forage, cost savings

Cows will drink approximately 14 times a day, consuming __ L each time

5-7

How can water intake impact DMI of rations?

40% reduction → 16-24% decline in the latter

When do cows drink 50-60% of total intake?

Post milking

About how much trough space should be preserved per cow to facilitate adequate water intake?

0.7m

What aspects of feeding are reviewed under “bunk management?”

Animal grouping, phyiscal facilities, the environemnt, mixing of feed, physical nature of the feed, timing and frequency of feeding, management of the feed face, feed quality, feed palatability, feed stability

What behaviors do cows prefer to exhibit around feeding and drinking times?

Habits, social interactions, curiosity and hierarchies

When do cows show peak feed consumption behaviors?

Post milking and following allocation of fresh feed

Why should we be cautious about moving first time lactation animals?

Growing evidence that subordinate animals produce 3.8-4.5% less milk and potential long term health effects result

Why is it generally accepted to separate heifers from cows?

The younger are typically smaller and more subordinate animals, most obvious group susceptible to bullying and stress

Feed dfifferences in behavior and intake between old and young cattle

When is the right time to mix cows?

Second lactation, introducing heifer group once in calf for a few weeks or during the dry period

What factors would influence an increased DMI in cows?

Complete (TMR) diet, out of parlor feeders, and mixed forages offered

What factors would influence a decreased DMI in cows?

Self feed silage, electric wire at feed face, poorly preserved silage

What is the ideal bunk space for cow feed access?

15-40cm from standing height

What happens if feed bunks are set less than 15 cm from standing height?

Less reach and more weight on front feet for longer

What happens if feed bunks are set more than 40 cm from standing height?

Cow commands more bunk space and may begin tossing feed

What surfaces do cows tend to prefer?

Smooth, light colored, or well lit

What qualities/ingredients may lead cows to find a ration unpalatable?

Calcium soap fats in excess, high ash content, urea/rape, dry or ‘burnt’ silage

When should you clean out bunks?

Daily

Why is forage quality so important in dairy nutrition?

Critical to drive DMI and a major determinant of ration palatability

>50% of DM proportion of ration

What is the only way to achieve high yields, cost effectively, and with good animal health?

Feed high quality forage

Why is good ventilation of feedstuff and feed areas considered essential?

Reduces humidity, noxious gases, pathogens, and drafts decreasing stress

What are four of the main ways that nutrition management can go wrong?

Poor maintenance of feeds, inaccurate quantities, poor mixing, poor distribution

If you have grass silage at 30% DM, and cows to be fed 10kg DM daily, how much fresh weight for a cow? 200 cows?

33kg, 6667 kg

How long does it take a cow to alter her microbiome after a diet change?

2 days to 2 weeks

Why is mix consistency so important in dairy herds?

To achieve optimal nutrient balance, every day the same, every palce the same, every mouthful the same

What are some factors that contribute to poor mix? (6)

Ingredient characteristics, improper sequence of addition, incorrect mix time, mixer overload, worn or broken mixing components, ingredient build-up