Calf Feeding Practices in Relation to Health

R.W. Blowey, BSc, BVSc, MRCVS 124 Stroud Road, Gloucester, England

Key Factors total stomach capacity) and the groove is deflected to run in a ventro-medio-caudal direction, in other words, • Stimulation of oesophageal groove closure is diagonally downwards, towards the right. achieved from the delight offeeding, not just thirst. • Many management features lead to poor groove Closure Mechanisms closure, which in turn causes colic, bloat and ill­ The muscles of the groove are controlled by the thrift. vagus nerve. There are three steps in groove closure: • Formation of the abomasal milk clot is an impor­ tant first stage in digestion. 1. Contraction of the pillars, pulling the lips of the • Most milk substitute problems are associated with groove together. incorrect mixing. 2. Contraction of longitudinal muscles, leading to • Abomasal dilation and ulceration may be caused shortening of the groove. by irregular feeding. 3. Twisting of the right lip, so that it curls over and • The causes of chronic post-weaning scour are of­ conceals the left lip, thereby totally enclosing the ten difficult to identify. channel.

Although infectious diseases are common in young The stimuli which produce groove closure also in­ calves, often their appearance is a consequence of some duce a simultaneous dilation of the reticulo-omasal failure of management. This paper considers some of orifice and an opening of the omasal canal. Milk can the factors which may be involved. now flow directly into the abomasum. Sucking produces quite high vacuums, e.g. The Oesophageal Groove 40mm Hg below atmospheric in teat 200mm Hg below atmospheric in mouth The calf is a ruminant and in common with other ruminants it has four stomachs, namely the reticulum, (cf. milking machine vacuum= 380mm Hg) rumen, omasum and abomasum. The very young calf only Suckled milk is therefore projected rapidly into and uses its fourth stomach, the abomasum, and functions through the cervical oesophagus. A separate series of essentially as a monogastric animal. Milk has to flow di­ pulsatile movements of the caudal oesophagus propels rectly from the oesophagus into the abomasum, liquid through the reticular groove and quite forcefully by-passing the rumen and reticulum via the oesophageal into the abomasum. During sucking, ruminal activity groove. When the groove is in the open position, milk virtually ceases. passing from the oesophagus would fall into the rumen, Even in the adult, the groove continues to contract, become sour and cause a digestive upset. When the groove some 3000-4000 times per day, when it acts to draw closes, a "pipe" is formed which transports milk directly fluid from the reticulum into the omasum with each through to the omasum and into the abomasum. contraction. The oesophageal groove is a continuation of the Factors stimulating groove closure lower oesophagus, passing across the medial wall of the Home (1806): postulated the role of the oesophageal reticulum and terminating in the reticulo-omasal ori­ groove to prevent milk entering the rumen, Webster fice. In the young calf, where the abomasum comprises (1926): assessed oesophageal groove closure manually 60% of the capacity of all the four stomachs, the aboma­ through a ruminal fistula. He showed that: ·sum lies ventrally and slightly to the left of the abdomen. The groove now runs almost vertically. As rumen devel­ 1. In the very young calf, the groove closed when suck­ opment progresses, the abomasum is pushed towards ing milk or water. the right flank (abomasum now equals only 10 - 15% of 2. However, milk was much more effective than wa- Paper presented at the BCVA Summer Meeting, July 1994 and published in Cattle Practice JBCVA Vol. 2, Part 3, July 1994

76 THE BOVINE PRACTITIONER-NO. 29 ter after 2-3-weeks old. 7. Slow drinkers present a problem. Milk left in front 3. The groove did not close when of them cools down and if drunk later may lead to - milk was fed through a tube directly in to the groove spillage. upper cervical oesophagus Milk spilling into the reticulo-rumen ferments to - the buccal and pharyngeal mucosa were anes­ produce colic, bloat and a chronic "pasty" diarrhea. Af­ thetized by swabbing with a local anesthetic. fected calves often become slow drinkers and this further - atropine was given (partially inhibits closure). exacerbates the problem. Bloat may be continuous or 4. Groove closure occurs in sham-fed calves (i.e. suck­ appear only 1-2 hours a._fter a feed. Treatment of affected led milk passes back out through an calves includes: oesophagostomy fistula and does not enter the abo­ masum). 1. Releasing gas with a stomach tube, if badly This work has since been repeated by others and bloated. shows that oesophageal groove closure requires a com­ 2. Remove milk and feed with electrolytes only for 3- plex series of stimuli. It is not sufficient for the calf 4 days. simply to suckle from a teat. It needs to build up a be­ 3. Oral antibiotics to suppress ruminal fermentation. havioral pattern, associated with suckling and it is the 4. Remove concentrates for 1-2 weeks. activation of the whole behavioral pattern, through a 5. Slowly reintroduce milk, preferably through a teat, range of visual, olfactory, thermal and chemical stimuli, to encourage suckling and groove closure. which affects full groove closure. The mechanism can 6. Severe or recurrent cases are best surgically pre­ be suppressed significantly by prior administration of pared with a permanent ruminal fistula. Such intravenous adrenalin and hence stress inhibits closure. calves usually go ahead quite rapidly. The fistula It is the delight from suckling which activates groove can be removed surgically 6-12 months later. closure, not just the desire of thirst. Closure in the Adult Practical Considerations Transfer of nutrients and especially pharmaceuti­ Groove closure is stimulated by sight, sound, taste cals (e.g. anthelmintics) directly into the abomasum of and other stimuli associated with feeding. It is there­ the adult ruminant can have pronounced advantages. fore very important to build up a specific feeding pattern Nutrients may be more efficiently utilized and phar­ so that the calves know what to expect. They need to be maceuticals more effective. "wooed into the mood" and ideally should be able to ex­ Copper sulphate solutions produce groove closures perience some of the activity of feed preparation prior in sheep, but are not particularly effective in cattle. Prob­ to its allocation. Poor groove closure results from: ably the most effective is prior drenching with 60ml of 10% ·sodium bicarbonate, which achieves groove closure 1. Irregular feeding times and/or feeding pattern. For with a 93% efficiency (Reilk 1954). Less concentrated example: solutions (e.g. 5%) are less effective. Both the anion and feed at the same time of day. feed housed calves in the same order. cation must be important, since sodium sulphate and remove the same bucket (e.g. concentrates?) sodium acetate achieve only poor groove closure. So­ each time and replace it with milk dium chloride is also effective, but less so than sodium let the calf see and hear the milk being prepared. bicarbonate (Reilk 1954). 2. Incorrect/variable milk temperatures. Scholz (1990) reviewed the use of lysine vaso­ 3. Feeding after stress - pressin to produce groove closure. Intravenous moving administration of 40iu immediately prior to drenching arrival from Market improved the clinical response of diarrhoeic cows given dehorning oral absorbents and saline and ofk~totic cows given oral castration glucose, compared with controls. 4. Incorrect position of the feeding point, e.g. the base The effectiveness of different benzimidazole of the feeding bucket should be at least 30cm above anthelmintics depends on their ability to bypass the floor level. This means that the bucket needs rais­ rumino-reticulum via the oesophageal groove and pass ing as straw accumulates in the pen. directly into the rumen (Pritchard & Hennessy 1981). 5. Sudden changes of flow rate from the teats, espe­ cially from slow to extremely rapid. This can The Abomasal Milk Clot overload the groove and lead to spillage. 6. Lack of "mothering" in the general sense. Drench­ For both whole milk and the majority of milk sub­ ing clearly does not produce groove closure. stitutes, formation of a milk clot in the abomasum is an

SEPTEMBER, 1995 77 essential first step in the process of digestion. Under cold a variety of problems can arise: the influence of the enzyme rennin and in an acid envi­ - the fat may be poorly dispersed. It rises to the top ronment, the protein in the milk clot solidifies and then of the milk and leaves a ring around the calfs nose, contracts, squeezing out the liquid whey fraction (con­ often leading to hair loss. If your calves develop bald taining non-casein whey proteins and sugars such as noses, check your milk substitute mixing routine. lactose) which then passes down into the small intes­ - proteins and minerals may form a sediment at the tine. The clot in the abomasum is slowly digested by bottom of the bucket and be wasted the enzymes pepsin (digesting casein) and lipase (di­ - oesophageal groove closure is poor gesting the fat) and any remaining material forms a - milk clotting time in the abomasum is retarded. A focus for the next milk clot. The small intestine is alka­ reduction of only 6° C may double the time for the line, digestion being carried out by enzymes produced abomasal milk clot to form. There is then an in­ by the pancreas. Lactose is split into glucose and galac­ creased risk of undigested milk spilling over into tose, two simple sugars which can be absorbed and used the small intestine. by the calf for energy. Protein is split into amino acids which can also be absorbed. If a long row of calves has to be fed from a single If abomasal milk clot formation is poor, then whole container, the milk for the last calf in the row can be milk passes into the small intestine, where casein can­ appreciably cooler - again, watch for bald noses! not be digested. This provides an excellent medium for Inefficient mixing is probably the biggest problem. bacterial fermentation and scouring results. Some of the Mixing with the hand is simply not adequate - a whisk adverse factors associated with poor clot formation are: is essential. Carelessly mixed powders leave lumps, • irregular feeding times poorly dispersed fat and a protein sediment in the bot­ • nervous or stressed calves tom of the bucket. Trials have shown that up to 60% of • overfeeding, especially in the young calf the oils in the replacer may be wasted in this way, in • milk fed at the wrong temperature addition to problems arising from poor abomasal clot • milk substitute fed at the incorrect strength formation and subsequent scouring. Ensure that the • inflammation of the abomasum: milk is mixed at the correct strength. This is usually 125g per liter, but may be increased to 150g per liter if Some of the newer milk substitute powders, espe­ fed once daily. Do not dilute milk powder, for example, cially those associated with ad libitum acidified cold for a scouring calf. If fed diluted, abomasal milk clot milk feeding, do not need to form an abomasal clot. Over­ formation will be retarded. Similarly, do not allow a calf feeding, leading to improperly digested food passing into to drink large quantities of water immediately after it the intestine, is still important however, even though has finished its milk, as this will have an effect equiva­ the acidified milk helps to prevent excessive bacterial lent to diluting the milk. When the milk bucket is empty, growth. it is best to put in a handful of coarse mix or calf pen­ cils, or immediately replace with the concentrate bucket. Problems with Milk Substitutes Some people remove the water bucket for 30-40 min­ There is a wide variety of milk substitutes on the utes after feeding milk. market. Many are based on a high level of skim milk Certain brands of electrolytes can be mixed with powder and form a clot in the abomasum, although some whole milk and actually improve clotting time, but the of the newer products, so-called "zero" replacers, because clot formed may be less stable. In general, therefore, it skim milk powder is absent, do not form a clot. If milk is best to avoid diluting milk. Ifelectrolytes are needed, powder is overheated during manufacture, then clot feed four times daily, twice with milk or milk substi­ formation is poor and scouring may result. However, tute, and twice with electrolytes. most of the problems associated with milk substitutes Finally, do not feed excessive quantities. Most are "on farm" in their origin. feeding schedules are designed for a 40kg calf and sug­ The first golden rule must be to read the gest starting at one liter per feed of the first 4-5 days, manufacturer's instructions. Many manufacturers increasing by 0.25 liter every second day, up to two li­ recommend that milk is first mixed at a higher tem­ ters per feed by 10-12 days old. If you have a smaller perature (45-50°C) before feeding. To do this a calf, feed less. Overloading the abomasum can lead to thermometer is needed. You cannot accurately judge the "spillage" and scouring. In summary, the golden rules t~mperature of the milk using your hand. On a cold day for feeding calves with milk substitute are: you will overestimate the milk temperature and feed it • correct temperature too cold and vice versa on a hot day. Trials have shown • correct strength that if the milk is too hot, a calf simply will not drink it • properly mixed and no harm is done. However, if it is mixed and fed too • fed in the correct amount.

78 THE BOVINE PRACTITIONER-NO. 29 Hair loss around the muzzle is likely to be a Chronic Diarrhea sign of problems. There is a well-recognized syndrome of a chronic, Abomasal Disorders pasty diarrhea, which may occur pre- or post-weaning and from which no specific pathogens (e.g. cocci, Abomasal Dilation cryptosporidia etc.) can be identified. Some cases are This is a condition of sudden onset also seen in idiopathic, others may be related to a feed or manage­ beef suckler calves. The calf is presented as being dull, ment change. Clinically the syndrome appears to be a dehydrated and often having colic. Large quantities of ruminal disturbance and hence may be associated with fluid are audible on auscultation. This prognosis is poor a number of factors, for example: and treatment includes: • managemental and other problems leading to abo­ l. Abomasal fiushing. Place the calf in lateral recum­ masal groove failure, "souring" of the rumen and bency on a bale of straw. Pass a gastric feeding subsequent poor development. tube into the abomasum, run in an electrolyte so­ • sudden feed changes lution and allow it to flush out under gravity. • excess starch and inadequate fiber in the ration, 2. Metaclopramide ("Emequell''). Used as an anti­ leading to poor development of the rumen wall. nausea agent in man, promotes ruminal and Many proprietary calffeeds contain nutritionally abomasal activity in cattle. Give 4-6cc (3 vials) in­ improved straw (NIS) to stimulate rumen devel­ travenously and repeat in 12 hours. opment. I have experienced one case where feeding 3. Intravenous sodium bicarbonate therapy. Using a a home-mix ofrolled/ground barley and wheat led Harleco bicarbonate measuring system, Dai Grove­ to chronic bloat and post-weaning scour for sev­ White has found that the majority of calves with eral years. This resolved following the feeding of a severe abomasal dilation and bloat are acidotic and proprietary calf ration. respond well to intravenous bicarbonate therapy • unsuitable feeds, e.g. high intakes of maize gluten (e.g. plasma bicarbonate at 4-10 mmol/liter, com­ to young calves. Remember that the calf is not a pared with a normal value of approximately 25 full ruminant until it is at least 12 weeks old. Prior mmol/liter. Total "bicarbonate space" is assumed to this the rumen is much more acid than in the to be 0.4 liters per kilogram bodyweight, i.e. 24 adult and feeds which further increase ruminal liters for a 60kg calf). acidity are contra-indicated. The syndrome is sometimes seen on farms where adult dairy con­ Abomasal Ulceration centrates are fed to young calves. Studies have shown that a surprisingly high pro­ portion of otherwise clinically healthy calves raised for Treatment is often difficult. Badly affected calves veal have evidence of chronic ulceration at slaughter. should be returned to a whole milk diet, with almost In a few herds there may be significant mortality due total removal of solid food, and maintained on this for to abomasal ulceration in calves 2-4 weeks old. Sug­ 3-5 weeks, depending on the severity of the condition. gested causes include: The use of a coarse calf ration in such cases is often l. Irregular feeding times, leading to excessively hun­ beneficial. While I accept that trials have shown no sig­ gry pre-ruminant calves eating excessive nificant difference between calf pellets and coarse mix quantities of hay or straw. Undigested fibrous ma­ in healthy calves, I have seen occasions where the use terial then passes into the abomasum and acts of coarse mix appears to have alleviated instances of as an irritant. ruminal bloat or chronic diarrhea. On one farm, where 2. Abomasal overload. Excessive quantities of milk intakes were carefully monitored, calves were found to or milk substitute entering the abomasum over­ eat coarse mix rations more slowly than pellets and loads the digestive enzymes, leading to poor clot there was more vigorous chewing. This would promote formation and "souring" with resulting inflamma­ the flow of saliva, reduce ruminal acidosis and improve tion. I have seen one such problem resolved overall rumen function. · following the fitting of teats with slower flow rates. In another recent case, gross overfeeding (2-2.5 References liters twice daily, given to 4-day old calves) led to death due to abomasal dilation and ulceration. The Pritchard RK & Hennessy DR (1981) Res. Vet. Sci. 30 22 Reilk RF problem was resolved by changing to feeding one (l954)Aust. "\kt. J. 20 29 Scholz H (1990) "\kt. Annual 3049 Webster J (1926) "Die Physiologie und Pathologie der Vormagen der Rinde", liter three times daily. Berlin p. 37. 3. Stress, leading to changes similar to gastric ulcer­ ation in man.

SEPTEMBER, 1995 79