10.1/10.2 - Dairy Cattle

acidosis

• occurs when pH of rumen falls below 5.5

• the change in acidity changes rumen flora → acid-producing bacteria take over

  • bacteria produce more acid, making acidosis worse

• increased acid absorbed through rumen wall, causing metabolic acidosis → in severe cases can lead to shock & death

cause of acidosis

feeding high levels of rapidly digestible carbohydrates

• seen in dairy cattle as a result of feeding increased concentrates compared to forage

symptoms of acidosis

symptoms:

• reduced feed intake

• poor body condition & weight loss

• lethargy

milk fever

• disorder mainly of dairy cows close to calving

• caused by low blood calcium level (hypocalcemia)

• losses:

  • due to deaths (1 in 20 affected die)

  • reduction in productive lifespan of each cow affected is ~3 years

  • reduction in milk production following each episode, as well as costs of prevention & treatment

cause of milk fever

~80% of cases occur within 1 day of calving

• milk & colostrum production drain Ca (& other substances) from the blood, some cows unable to replace Ca fast enough

• higher producers more susceptible due to decrease fall in blood Ca level

symptoms of milk fever

typical cases, some initial excitement or agitations & tremor in muscles of head & limbs → start to stagger & go down to a “sitting” position, often with a “kink” in her neck → lie flat on their side → circulatory collapse, coma, death

treatment for milk fever

oral Ca gel/bolus or Ca gluconate under skin

displaced abdomen (DA)

• abomasum (true stomach) normally lies on floor of abdomen → can become filed with gas & rises to the top of abdomen (becomes “displaced”)

  treatment: requires replacing abomasum in its normal position

  • preferably, vet prevents recurrence by tacking abomasum to body wall

  • surgery can be performed (not always necessary)

  • abomasum can often be returned to usual place by casting & rolling cow onto its back, permitting abomasum to “float” back into its normal position

cause of displaced abomasum

majority of cases occur soon after calving

• during pregnancy, uterus displaces abdomen → after calving the abomasum has to move back to its normal position, increasing risk of displacement

symptoms of displaced abomasum

loss of appetite, drop in milk yield, reduced rumination, mild diarrhea

prevention for displaced abomasum

• ensure DM intake is maintained in early lactation

• ensure cattle aren’t too fat at calving

• feed high quality feeds, with good quality forage

• feed total mixed ration as opposed to concentrates

• minimize changes between late dry and early lactation ration

  • likely that farm with numerous DA problems is feeding late/dry &/or early lactation cows

ketosis

• occurs when energy demands exceed energy intake, & result in negative energy balance

• body condition of dairy cow important at calving

  • cows should be on rising plane of nutrient up to calving with aim to calve in good condition

  • after calving, cow has potential to reach maximum efficiency in milk production → feed requirements for high production are greater than voluntary intake of pasture can provide

• energy supplement is required

  • evidence that this improves production & reproductive performance, & decreases risk of ketosis

cause of ketosis

when large amounts of body fat are utilized as an energy source to support production

• fat is sometimes mobilized faster than the liver can properly metabolize

  • ketone production exceeds ketone utilization

    • in dairy cows, mismatch between input & output usually occurs in the 1st week

symptoms of ketosis

• reduced milk yield

• weight loss

• reduced appetite

• acetone (pear drop) smell of breath/or milk

• may develop nervous signs

  • excessive salivation & licking, aggression, etc

treatment for ketosis

initial aim is to restore lack of glucose in the body

• quick acting glucose supplement required immediately

follow up treatment: aimed at providing long term supply of glucose

production & nutrients

• need to consume a lot of feed to achieve levels of production

  • some cows produce more than 34,000 lbs of milk annually (over 4200 gal)

• nutrient needs vary tremendously throughout the lactation & dry period cycle

  • at peak production: may require 3-10x as much protein & energy as she required during gestation

  • further complicated: cows appetite usually lacks behind nutrient requirements

challenge of dairy feeding program

meet cows nutrient needs while minimizing body weight loss & digestive upsets, & maintaining cow health

the cycle

relationship between milk production, dry matter intake & body weight changes typically observed during normal lactation/gestation cycle

when is peak milk production reached

6 - 9 weeks after calving

• increases rapidly

maximum daily dry intake

occurs 12 - 15 weeks postpartum

how long are cows in a negative energy balance

8 - 10 weeks

• possibly as long as 20+ weeks

how much body weight is does a cow in good condition lose during early lactation

90 - 135 kgs

• has to support 700 - 900 kg of milk production

what happens when there is a lack of nutrient sources

peak production & total lactational production will likely be less than optimal

optimal dry matter intake achieved

• occurs once cows appetite increases

• intake follows production requirements and decreases as production decreases

• cows tend to consume more than she needs during later lactation → allows her to gain body weight that was lost in early lactation

• cow should regain most of lost body weight during late lactation for optimal energetic efficiency

• weight gain during dry period accounted for by fetal growth

bovine somatotropin (bST)

• for cows injected with bST, there may bee a second increase in production within a few days of initial injections

  • may again experience a short term negative energy balance → appetite lags behind protsiton

• production typically increases about 10% as result of bST injection

  • dry matter intake needs to increase 2-3% to supply nutrients for increased production

phased feeding

lactation & gentian cycle can be divided into 5 phases based on nutritional considerations

phase 1

• first 10 weeks of lactation

• when peak production occurs & body stores are used to make up for nutrient intake deficiencies

phase 2

• about 10 weeks postpartum for most cows

• continuing for 10-20 weeks

• maximum dry matter intake

• intake is in balance with requirements

phase 3

• intake exceeds nutrient requirements for production, restoring body reserves

• main period for restoring body stores for next lactation

phase 4

• period for final regain of body weight

• involution followed by regeneration of secretory tissue in udder for next laction

phase 5

• last 1-3 weeks pre-partum

• transition period

• increasing grain intake as mean of prepping rumen for increased nutritional intake that follows after giving birth

dry period

• 6-8 weeks

• cow needs short dry period as rest while prepping for next lactation

• dry periods shorter than 40 days → don’t allow enough time for udder regeneration

  • may cause decrease in production during next lactation

• regenerate new secretory tissue & replace lost body condition

• milk continues to be secreted for several days after drying off before active involution takes over

changes that occur in udder during dry period

• active involution; steady state involution

• lactogenesis + colostrogenesis

active involution

• completed 30 days into dry period

• milk-secreting tissue is reabsorbed

steady-state involution

can exist indefinitely & mammary gland remains in collapses state

lactogenesis + colostrogenesis

• begins 15-20 days pre-partum

• involves onset of lactation & secretion of colostrum

dry cow feeding

• emphasizes maintaining BCS

• USDA research shows that cows convert feed energy to body tissue more efficiently in late lactation than during dry period

• if still thin at drying off, need to replenish body stores & provide for fetal growth

body condition at calving

• BCS of 3.5 at calving

  • scale of 1 - 5

    • 1= very thin; 5= excessively fat

  • ideal for high milk yield, fat test, & reproductive performance

  • cow should be in ideal calving condition when she goes dry

    • weight gain during dry period is mostly accounted for by growth of fetus

dry cow rations

• nutrient requirements can often be met with forages only

  • legume-grass hay & corn silage combo needs only vitamins & small amount of P to meet requirements

• ration can be simple but should include:

  • minimum of 1% body weight as long-stem, dry forage (preferably grass hay)

  • free choice feeding of corn silages should be AVOIDED

    • leads to excessive energy intake, increases likelihood of DA & fat cow syndrome

    • grains should be limited to energy & protein needs

fat cows

• consuming excess energy from grain &/or corn silage likely to develop fat cow syndrome

  • leads to calving difficulties, DAs, ketosis, & other health problems

• cows fed hay &/haylage are less likely to have problems than cows recieving free-choice corn silage

  • limit corn silage for dry cows to 9.5-11 kg/day

    • puls a protein & Ca-P supplement

fat cow syndrome

high blood lipids & fatter liver

bred heifer nutrient requirements

• slightly greater during late gestation than that of dry cows

  • will likely need some grain along with forages during last 3-4 months of gestation (still growing)

  • good quality forages can provide all nutrient needs during early gestation

  • if forages not food quality or heifers exposed to severe weather condition, additional grain may need to be needed to maintain optimal growth

  • usually fed in groups of similar age/size

transition period (phase 5)

time to make several nutritional changes to help cow prep for partition & lactation

• in the last weeks before partition:

  • aim to adapt rumen microflora to higher-energy diets needs postpartum

    • allows cow to meet her greatly increased nutrient requiremtns for lactation

  • adjustment often achieved by including small amounts of all ingredients of lactation ration

    • gradually increase concentration → “steaming up”

    • minimize chances for milk fever & ketosis during lactation

• most cows experience sharp decrease in TDM intake 24-48 hrs before calving

  • stabilizing rumen is important to avoid DA, acidosis, & off-feed

post-calving objectives

1. increase feed intake as rapidly as possible (to minimize nutritional deficit), but not to cause digestive upsets & go off-feed

2. once stress of calving passes, increase concentrate intake yo 0.5-0.7 kg/day

3. if total mixed ration fed, this equates to forage: concentrate ratio of 55:45 or 50:50

period that appetite lags behind nuttiornal requiremtsn

partition until peak milk production

• peak milk production (phase 1) is negative nutrient balance period

peak milk production

• forage portion of diet should be less than 45% of the diets dry matter

• successful phase 1 feeding:

  • maximizes peak milk yield

  • utilizes some body weight as energy source

  • minimizes ketosis

  • returns cow to positive energy balance by 8-10 weeks postpartum

cows compensate for deficit in energy intake

• borrow remaining needed energy from body fat

• cannot borrow very much protein → protein must be supplied in diet

• early lactation cows benefit from rumen bypass (escape) proteins

rumen bypass (escape) proteins

allows proteins to bypass microbes in rumen & proceed directly to abomasum, where cow can derive the benefits from dietary protein

non-protein nitrogen supplements

not used efficiently by cows compensating their deficit in energy intake

acidosis & peak milk production

• increasing energy density helps early lactation cow meet energy requiremnts

  • can be partially achieved by increased proportion of concentrate/grain in ration

  • higher starch, lower fiber diets are more apt to cause acidosis, digestive upsets & milk fat depression

    • non-structural carbs (starches & sugars) should be limited to 30-40% of the diets dry matter

  • feeds such as distillers grain (containing abundance of readily digestible fiber & some fat) can replace sizable amount of high starch feeds, producing more energy, & decreasing rumen acidosis

supplemental dietary fat

• may allow increased energy density & adequate fiber intake

  • limits to how much fat can be fed

hay in daily ration

providing at least 2.25 kg dry hay/day helps maintain normal rumination & digestion, especially during early lactation

maximum dry matter intake

• should be achieved as early in lactation as possible

• conception rates greater for vows in positive energy balance than those in negative energy balance → cows usually bred during this phase of lactation

• body weight should stabilize & weight gain should start occurring in this phase

• maximum DM intake will reach 3.5-4.5% of body weight

• DM intake usually higher for higher producing cows

  • not unusual for some cows to consume more than 5% of their body weight

late lactation

• easiest phase to manage

  • cow is pregnant

  • nutrient intakes exceeds requirements

  • milk production decreased

• time to replace the weight lost in early lactation so that cow is in good condition at drying off

• maintain milk persistency

young cows during late lactation

• still growing

  • need additional nutrients for growth & weight gain

• usual guidelines for estiamating nutrient requirements for growth

  • 20

  • 20% of maintenance for 2 year olds

  • 10% of maintenance for 3 year olds

feeding during late lactation

• minimize feed cost by increasing forage

  • concentrate ratio to match nutrient needs based on cows milk production & body condition

• lower protein content

  • protein:energy ratio needed for weight gain is less than the ratio needed for milk production

  • NPN sources may be utilized

    • bypass proteins will be less cost effective than in earlier lactation, when production is higher

energy for lactating cows

• gestation-lactation curve ends with lactation

• challenge is to get cows to consume sufficient amounts of energy, especially during early lactation

energy intake may be increase by:

• increasing the energy density of the hit

• increasing readily fermentable carbs

• increasing dry matter intake

  • anything that stimulates DM intake allows for continued feeding of normal diets that may be higher in fiber

added fat

• energy density can be increased by replacing portions of carbs in the diet with fat

• 1 kg of fat contains ~2.25x as much energy as 1 kg of carbs

• allows for increase in energy intake while avoiding excessive starch or deficient fiber intake

• cows can consume more fat than is usually present in forage & grain mixes, but cannot consume an unlimited amount of fat

fat content in grains & forages

• contain 2-4% fat

  • fat can be increased to 5-7% of total diet DM, without adversely affecting feed intake or nutrient utilization

  • more than 8-10% fat may decrease feed intake & fiber digestibility, and cause digestive upsets

fat sources NOT suitable for milking cows

free oils (soybean oil, sunflower oil, cottonseed oil, corn oil, fish oils)

• often affect rumen fermentation adversely → reduced fiber digestion & lowered milk fat tests

feeding groups

• cows grouped according to various needs

  • number of groups depends on size of the herd & facilities available

    • ex. dry cows split into 2 groups

      • far off

      • close-up transition

    • body condition

    • milk production

• cows have social dominance hierarchies

• group cows by reproductive status, keeping cows that need to be bred in one pen → may make heat detection easier

• when moving cows from one group to another, make sure shift doesn’t cause undue stress

  • recommended to move groups of cows rather than individuals

calves

• first critical days

  • health & vigor of cows at birth depends on the nutrition of the cow during the last 60 days before freshening

    • during this period, calf develops ~70% go its birth weight

cow during first critical days of calf

• must store nutrients for early lactation

• milk production exceeds cows capacity for feed consumption

• if properly fed & immunized against locally prevalent pathogens, colostrum will have good antibody quality

colostrum

• calves born without functioning immune system → cannot at first synthesize antibodies, need colostrum at birth

• supplies antibodies needed by newborn & acts a laxative to aid in starting calves digestive fountain

• calves should receive a minimum of 2 quarts of colostrum in two feeding in their first 12 hours

• under commercial conditions, fairy calves rarely recieve colostrum from their mothers

  • freshened cows milked, colostrum kept separate from milk destined for market

  • colostrum tested for quality → if good quality, it is either fed fresh or frozen

digestion of newborn calves

• reticulum, rumen, omasum, & abomasum are not developed yet

• digestive tract/processes similar to monogastric animals

  • rumen not fully developed until cold reaches weight of 200 kg

• rumen doesn’t start to be populated with microbes until the calf is ~60 days old

  • microbes produce VFAs → causes tissues lining the rumen to mature & develop

  • calf must be supplied with whole milk or milk replacer

first 60 days of feeding

• calve must elevate head to nurse using a nipple → activates the esophageal groove

  • calves fed by lowering their head to drink from a bucket don’t activate esophageal groove as well

• milk flows directly to omasum & abomasum, bypassing the rumen

  • the more calves are fed to approximate natural conditions, the more efficient their performance will be

milk replacer

• selection of milk replacer important for good results In raising dairy calves

• high quality milk replacer should be used for at least first 3 weeks

• milk replacers of relative lower quality can be used for healthy calves artery they are at least 3 weeks of age

• quality is determined by the type of & amount of protein and fat

  • milk protein sources (dried whey, skim milk, casein) are superior to plant or animal protein sources

• many milk replacers contain antibiotics (tetracyclines)

• vitamin E has been recommended at levels as high as 135 IU day for calves during time prior to weaning

starter diets

• should be offered at ~1 week of age

  • standard ingredients used in dairy feeds can be used for starter rations, but fine-ground feeds are NOT acceptable

• good quality alfalfa hay should be offered in small amounts

  • extremely leafy, find-stemmed alfalfa may lead to scouring because of excess protein intake

  • too much at at this time can reduce the energy density of the diet → may lead to lower gains & interfere with rumen development

• consumption of starter feed is critical to development of an active, functioning rumen

when should calves be weaned

once they are consuming ~2 kg of started feed in addition to hay & milk replacer

2 approaches to weaning calves off milk replacer

abruptly remove milk replacer so calves have to utilize the starter ration

OR

gradually add increasing amounts of water to milk replacer, until its only water

before weaning

• calves should be removed from hutches to small group pens → 100 ft² of space/calf, max of 10 calves/pen

• weaned calves can be moved to younger group pens & offered growing rations → separate growing calves by size if possible

heifers

• if properly introduced to solid feed before weaning, growing ration can be gradually changed so they reach puberty at 15 months

• goal: max growth/min. fat deposition

gestation: 2 phases nutritionally

• breeding to 60 days before calving

• late gestation

nutrition from breeding to 60 days before calving

• ration should be designed for growth, with fat deposition avoided

• if fed high-energy, low-protein rations, cows tend to deposit fat in the udder, limiting future production capability

• pasture & other feedstuffs low in DM are important to breeding programs for bred heifers

nutrition during late gestation

• grain mix similar to that used when they enter lactation

• adjust rumen population to increase microbes that ferment lactation ratio feeds

• increase nutrient intake for storage to support early lactation + growth

• provide for increased demand in nutrients by rapidly developing fetus

• transition from early gestation ration to ration containing a grain mix designed to support lactation should be made gradually, over a period of several feedings

summary

• dairy cows managed on annual gestation-lactation cycle

• if you superimpose lactation cycle, body weight changes, DM intake & compare them to milk production, the cycle divides itself into 5 distinct feeding phases

• during 5 phases, balance body weight changes with balance of concentrates & forages in the ration to maintain milk production & healthy gut microflora

• increase forage content in late lactation

• challenges in early lactation of getting cows to consume enough energy

• adding fat to diet can help with energy consumption

• care of cow the 60 days prior to partition increases health of newborn calf

• dairy calves raised & fed milk replacers

• divide gestation feeding program into 2 phases