NU­TRI­TIONAL NEEDS OF LONG LAY­ING HENS

The Poultry Bulletin - - FRONT PAGE - By Fran­cois Crots

The mod­ern lay­ing hen is dis­tinctly dif­fer­ent from old gen­er­a­tion lay­ers com­mer­cially farmed with in the early 1980s. This is due to com­pe­ti­tion be­tween breed­ing com­pa­nies for mar­ket share as well as the need to feed nine bil­lion peo­ple around the world. The main rise in lay­ing per­cent­age is based on longer clutch length and im­proved uni­for­mity of layer flocks.

The most pop­u­lar aim of pro­gres­sive layer ge­neti­cists is the 500-egg hen, in one cy­cle and with­out moult­ing. How­ever, eggshell qual­ity at the end of the pro­duc­tion pe­riod de­serves much more at­ten­tion and sup­port in com­par­i­son to a one-year pro­duc­tion cy­cle (72 weeks of life). The so-called post-peak dip shows up as an ad­di­tional chal­lenge at the be­gin­ning of the pro­duc­tion pe­riod. Both top­ics – a se­cured start of pro­duc­tion and reach­ing peak per­for­mance and op­ti­mal egg shell qual­ity up to 90 weeks of flock age (or more) are highly re­lated to op­ti­mal nu­tri­tion of high pro­lific layer flocks.

Ge­netic im­prove­ments

Pro­duc­tion records of the Hy-line Brown have been com­pared in Ta­ble 1 to serve as a prac­ti­cal ex­am­ple of the ge­netic im­prove­ment over the past 16 years. The mod­ern lay­ing hen is slightly lower in body­weight (40 g) at 17 weeks, but is sig­nif­i­cantly more ef­fi­cient dur­ing the rear­ing and pro­duc­tion pe­riod with over­all lower feed con­sump­tion. Other ma­jor im­prove­ments in­clude a 50% pro­duc­tion mark reached nine days ear­lier; the num­ber of eggs at 80 weeks in­creased by 21 eggs; the num­ber of weeks of egg pro­duc­tion over 90% in­creased by five weeks; feed con­ver­sion im­proved by 18 points; and the hen is able to lay at least 500 eggs up to 110 weeks.

Higher pro­duc­tive hen for achal­leng­ing eco­nomic pe­riod

Even though the mod­ern lay­ing hen has im­proved, the eco­nomic cli­mate has also changed dra­mat­i­cally. For ex­am­ple, Fig­ure 1 il­lus­trates the com­par­i­son in the pro­duc­tion curves of the Hy-line brown, 1998 vs 2014. One can ob­serve that the mod­ern lay­ing hen comes in to lay 1/2 weeks ear­lier and the pro­duc­tion af­ter 46 weeks of the 2014 hen is much more per­sis­tent. How­ever, in 1998, the av­er­age feed price was R911/ton and the pro­ducer was Nu­tri­tional needs of mod­ern long LAY­ING HENS

paid R3.72/dozen eggs, with an egg:feed price ra­tio of 2.04. In 2016, pro­duc­ers have paid, on av­er­age, R3700 for a ton of feed and were paid R11.50 for a dozen eggs, in­di­cat­ing a egg:feed price ra­tio of 1.56. The eco­nomic im­pli­ca­tion of this is that even though the mod­ern hen is much more pro­duc­tive, the time re­quired to reach the eco­nomic break-even of the hen has in­creased from 34 weeks in 1998 to 52 weeks in 2016. Pro­duc­ers there­fore only start to make profit af­ter 52 weeks, which in­di­cates that the longer pro­duc­tion cy­cles in the cur­rent eco­nomic client is im­per­a­tive and a 'life-line' to sur­vive the cur­rent eco­nomic chal­lenges with record high feed cost, low egg price and de­pressed dis­pos­able in­come.

So how does the com­mer­cial nu­tri­tion­ist feed the mod­ern, highly pro­duc­tive hen to en­sure that pro­duc­ers ex­tract the full fi­nan­cial ben­e­fit of the

ge­netic progress?

Poor shell qual­ity at any time not only re­sults in fi­nan­cial loss, but also causes ma­jor con­tam­i­na­tion prob­lems in highly mech­a­nised egg pack­ing and han­dling equip­ment. Poor shell qual­ity at 72 weeks does not mean that all hens in an age­ing flock pro­duce eggs of

re­duced qual­ity; rather that the vari­abil­ity in egg qual­ity within the flock in­creases. The long-term main­te­nance of the tis­sues and or­gans in­volved in pro­duc­ing eggs is there­fore a pre­req­ui­site for ex­tend­ing the lay­ing cy­cle of com­mer­cial flocks.

Some of the fac­tors that need to be con­sid­ered to

achieve 500 eggs in 100 weeks (via a per­sis­tence of lay) - and to in­crease the num­ber of sell­able eggs - in­clude the rear­ing pe­riod, feed par­ti­cle size dur­ing rear, gut health, cal­cium in­take, egg weight con­trol and the con­trol of meta­bolic dis­eases.

Im­prove over­all rear­ing weight of pul­lets

Op­ti­mal nu­tri­tion starts just af­ter hatch to de­velop a pul­let on an op­ti­mal body­weight, uni­for­mity and feed in­take ca­pac­ity. Grow­ing and de­vel­op­ing pul­lets cor­rectly in­flu­ences pro­duc­tion, per­sis­tency of the pro­duc­tion, and the per­sis­tency of shell qual­ity from the early stages of the lay­ing cy­cle.

Cor­rect de­vel­op­ment of the skele­ton, mus­cle and fat de­posits are crit­i­cal and highly in­flu­enced by nu­tri­tion. While early weight gain is im­por­tant, achiev­ing on, or above, tar­get weights by six weeks and con­tin­u­ing to 13 weeks is crit­i­cal, as this is when much of the bird’s mus­cle and frame de­vel­op­ment occurs. Small framed birds have lower bone mass and con­se­quently a lower medullary bone mass and cal­cium re­serve in the lay­ing pe­riod, which will likely re­sult in shell qual­ity loss ear­lier in the lay­ing cy­cle.

The use of crum­bled feed as op­posed to mash feed dur­ing the rear­ing pe­riod has proven to in­crease the body­weight of hens at point of lay. Ta­ble 2 in­di­cates that at 17 weeks of age, the hens were 131g heav­ier and had a 9-point im­prove­ment in FCR.

In a trail that was con­ducted in the Nether­lands, Lohman Clas­sic hens were reared

Non the 3 dif­fer­ent feeds, vary­ing in pro­tein and en­ergy con­cen­tra­tions that pro­duced birds with three dif­fer­ent body­weight pro­files. It can be ob­served (ta­ble 3) that the heav­ier hens con­sumed more feed dur­ing the 18 to 24-week pe­riod, but the lay­ing % and egg weight dur­ing the pe­riod were sig­nif­i­cantly higher. There was also a gen­eral trend that the feed con­ver­sion ra­tio im­proved with an in­crease in body­weight.

Know­ing flock feed in­take is crit­i­cal

utri­tion­ists can eas­ily calculate the daily de­mand for op­ti­mal eggshell de­vel­op­ment based on stan­dard sci­en­tific knowl­edge. Cal­cu­lat­ing the suf­fi­cient in­take of daily cal­cium needs

Sto be based on the daily feed in­take of an ac­tual, spe­cific flock. When tar­get­ing a 4,1g cal­cium in­take per hen per day, the amount of cal­cium in the diet needs to be ad­justed by up to 4,5% (90g ef­fec­tive am­bi­ent of daily feed in­take), or to 3,41% cal­cium with 120g feed per hen per day. With a change in sea­son, cal­cium and other crit­i­cal nu­tri­ents need to be ad­justed ac­cord­ing to the in­take of the birds.

4,10 g cal­cium needed x 100 120 g feed con­sumed = 3,41% cal­cium in the diet

Ac­cepted prac­tices to im­prove eggshell qual­ity

witch­ing lights on two hours ear­lier and in­tro­duc­ing a mid­night feed­ing has been shown to im­prove→

the syn­chro­ni­sa­tion of di­etary cal­cium in­take with shell for­ma­tion, and im­proved eggshell qual­ity. To op­ti­mise eggshell qual­ity, the cal­cium par­ti­cle size should also be ad­justed ac­cord­ing to the density and sol­u­bil­ity of the par­tic­u­late cal­cium source (quarry or ma­rine). Di­etary lipid con­tent and the ac­tive me­tab­o­lite of Vi­ta­min D3 have been shown to in­flu­ence the ef­fi­ciency of di­etary cal­cium up­take in the gas­tro-in­testi­nal tract. How this re­lates to the trans­fer of cal­cium in the shell gland re­mains to be de­ter­mined. High lev­els of phos­pho­rous, or too much or too lit­tle salt in the layer diet also have a dele­te­ri­ous ef­fect on eggshell qual­ity and should be avoided.

Syn­chro­nis­ing cal­cium in­take with egg for­ma­tion

Pro­tein, cal­cium and en­ergy re­quire­ments of lay­ing hens do not re­main con­stant, but vary dur­ing the day de­pend­ing on the hen’s phys­i­o­log­i­cal re­quire­ments for the var­i­ous stages of egg for­ma­tion. It is cal­cu­lated that 90% of a hen’s eggs are laid early in the morn­ing just af­ter the lights come on.

To­gether with our in­ter­na­tional tech­ni­cal part­ners, the AFGRI An­i­mal Feeds Re­search & De­vel­op­ment divi­sion de­vel­oped a feed­ing pro­gramme for lay­ing hens ac­cord­ing to the spe­cific nu­tri­ent re­quire­ments for egg for­ma­tion that varies through­out the day. Find­ings from years of re­search re­sulted in the for­mu­la­tion of South Africa’s first Split Feed­ing pro­gramme, where two di­ets (AM and PM) are used to meet

the dy­namic re­quire­ments for egg for­ma­tion.

The AM diet is de­signed to meet the re­quire­ments dur­ing the morn­ing when the al­bu­men is be­ing formed, and when ovu­la­tion and ovipo­si­tion oc­cur. The PM diet is de­signed to meet re­quire­ments for eggshell for­ma­tion that is high­est dur­ing the af­ter­noon pe­riod. New re­quire­ments for en­ergy, amino acids, cal­cium and phos­pho­rous were ob­tained for the AM and PM di­ets. Although the to­tal in­take of th­ese nu­tri­ents was re­duced, per­for­mance was at least as good as, if not bet­ter when com­pared to the sin­gle feed.

Eco­nomic ben­e­fits of the Split Feed­ing sys­tem

In a lo­cal ex­per­i­ment, the ef­fect of the Split Feed­ing sys­tem was tested at Son­dela Eggs near Eloff in Mpumalanga. House three with 13,091 Hy-line hens was fed the stan­dard com­plete mixed ra­tion, while House 4 housed 13,181 hens of the sis­ter flock, and was fed the Split Feed­ing ra­tions. Fig­ures 1, 2 and 3 il­lus­trate com­par­a­tive graphs for the houses’ pro­duc­tion, body­weight and per­cent­age of cracks. One can clearly ob­serve the per­sis­tence of lay in the split fed house birds. Their body­weight af­ter 62 weeks was higher and per­cent­age of cracks lower com­pared to the stan­dard fed birds.

Ta­ble 4 in­di­cates the pro­duc­tion and fi­nan­cial per­for­mance of the trial con­ducted. It can be con­cluded that a split fed bird pro­duced nine more sell­able eggs/hen, which trans­lated to R9,29/ hen, or al­ter­na­tively stated, an im­prove­ment of R120,825

Tper house com­pared to the stan­dard fed birds. The trial is still run­ning and the profit per hen is likely to in­crease as the non-split house was de­pleted since the level of pro­duc­tion was no longer eco­nom­i­cally vi­able to con­tinue the cy­cle.

Egg weight con­trol in age­ing flocks

o en­sure op­ti­mal eggshell qual­ity in ex­tended pro­duc­tion cy­cles, you need to con­sider the egg weight/ size. Due to the ag­ing cal­cium me­tab­o­lism, there is a de­creased per­cent­age of eggshell in re­la­tion to the to­tal egg weight in larger eggs. Breed­ing pro­grammes are pro­vid­ing flat­ter egg weight curves with higher weights in early lay and lower weights in later lay com­pared to pre­vi­ous gen­er­a­tions. Light­ing pro­grammes, ap­plied at both the be­gin­ning and end of the rear­ing pe­riod, also in­flu­ence egg weight.

Ap­pro­pri­ate rear­ing pro­grammes are an im­por­tant first step, be­cause nu­tri­tional in­ter­ven­tion to con­trol egg weight of­ten has a sec­ondary, detri­men­tal ef­fect on pro­duc­tion. In­di­vid­u­ally and in com­bi­na­tion, di­etary amino acid con­cen­tra­tion has been demon­strated to im­pact egg weight as well as pro­duc­tiv­ity, whilst sul­phur amino acid con­cen­tra­tion is most as­so­ci­ated with egg weight, and me­thio­n­ine and cys­teine con­cen­tra­tions are of­ten ad­justed to ob­tain the de­sired egg weight pro­file. There may also be an in­flu­ence from other nu­tri­ents re­lated to sul­phur amino acid me­tab­o­lism. Through in­volve­ment in the methy­la­tion path­way, choline/be­taine and even vi­ta­mins B12, B6 and folic acid may be rel­e­vant. Field re­sponses in­di­cated that egg weight can be con­trolled by re­duc­ing me­thio­n­ine + cys­teine con­cen­tra­tion whilst in­creas­ing the ra­tio of me­thio­n­ine:cys­teine to min­imise the im­pact on pro­duc­tion.

Feed­ing for per­sis­tency in lay

Dur­ing the lay­ing pe­riod, the first chal­lenge is to ad­just the en­ergy and pro­tein re­quire­ments to op­ti­mise egg out­put and to care­fully con­trol body­weight. Growth re­quire­ment is only present for the first few weeks at the on­set of egg pro­duc­tion. En­ergy re­quired for main­te­nance there­after de­pends on body­weight and feather cov­er­age, and in­creases with hen age.

Stud­ies show a strong neg­a­tive cor­re­la­tion be­tween feed in­take and di­etary en­ergy con­cen­tra­tion. This adap­ta­tion is only par­tial and high en­ergy di­ets can be used dur­ing the first part of the lay­ing pe­riod to sat­isfy the con­tin­ued re­quire­ment for growth and to pro­mote heav­ier, early egg weight with­out the risk of over­feed­ing and pro­duc­ing ‘fat hens’. The hen’s en­ergy re­quire­ment de­creases as egg pro­duc­tion be­comes es­tab­lished. To min­imise fat de­po­si­tion, a lower en­ergy diet can be used at this time, as the birds will be able to par­tially com­pen­sate by in­creas­ing their feed in­take. Lay­ing hens also ad­just their feed in­take ac­cord­ing to the rel­a­tive size of the par­ti­cles in re­la­tion to beak size. Vary­ing par­ti­cle size al­lows fur­ther bal­anc­ing of en­ergy in­take.

Crude pro­tein con­cen­tra­tion and amino acids in the layer diet are also im­por­tant; me­thio­n­ine is the main lim­it­ing amino acid. Con­sump­tion of an ex­tra 1g of pro­tein per day, for ex­am­ple, re­sults in an av­er­age in­crease in egg weight of 1,4g. The amount of pro­tein con­sumed is de­pen­dent on the di­etary en­ergy con­cen­tra­tion and the form of the ra­tion. Ide­ally, the pro­tein and amino acid con­cen­tra­tion in the diet should be es­ti­mated rel­a­tive to the egg weight (mg/g of egg for amino acids) and ad­justed to op­ti­mise egg pro­duc­tion through­out the lay­ing cy­cle. An ad­di­tional dif­fi­culty is that the het­ero­gene­ity of the flock in­creases with age. The best strat­egy is to fo­cus on main­tain­ing the pro­duc­tion of the higher pro­duc­ing hens and to ad­just the sup­ply of pro­teins and amino acids ac­cord­ingly, pro­vided the cost is not pro­hib­i­tive.

Liver health to sup­port egg pro­duc­tion

Feed­ing for liver health is not only a vet­eri­nar­ian is­sue, but also an im­por­tant nu­tri­tional topic. The liver pro­vides nearly all the ba­sic nu­tri­ents for yolk and al­bu­men de­vel­op­ment, and even sup­ports the de­vel­op­ment of the eggshell, pro­vid­ing the pro­tein in the eggshell, which is mainly re­spon­si­ble for a cer­tain elas­tic­ity of the shell. Feed­ing layer birds with a cer­tain amount of added fat and oil serve as a well-known tool to re­duce the in­ci­dence of so-called fatty liver syn­drome. A cer­tain amount of added choline chlo­ride in layer di­ets to sup­port the liver me­tab­o­lism should be a non-ques­tion­able stan­dard prac­tice. Every so­called fatty liver sup­ple­ment will be based on choline chlo­ride along­side im­por­tant vi­ta­mins (K3, E, B12, B1 and folic acid).

Dis­ease

Both dis­ease and en­vi­ron­men­tal stress can in­duce changes in egg for­ma­tion at any time dur­ing the lay­ing year. Dis­eases like in­fec­tious bron­chi­tis, egg drop syn­drome and New­cas­tle Dis­ease in­flu­ence egg qual­ity, ei­ther di­rectly by al­ter­ing oviduct struc­ture or in­di­rectly by low­er­ing the gen­eral health sta­tus of the in­di­vid­ual bird. Re­me­dial ac­tion in such cases of­ten in­volves med­i­cat­ing or vac­ci­nat­ing the en­tire flock with vari­able suc­cess.

Con­clu­sion

Ben­e­fits of ge­netic se­lec­tion for im­proved per­sis­tency in lay and sta­bil­ity in egg qual­ity can only be re­alised if they are matched by im­prove­ments in hen nu­tri­tion. It is how­ever up to com­mer­cial nu­tri­tion­ist, pro­duc­ers and vet­eri­nar­i­ans to form part­ner­ships to en­sure that the ge­netic ad­vances pack­aged in the mod­ern lay­ing hen is re­leased by ap­ply­ing the lat­est knowl­edge and tech­nol­ogy.

Fig­ure 1: Eco­nomic breakeven point 1998 vs 2014

Fig­ure 2: Body­weight com­par­i­son of stan­dard ver­sus split fed birds

Fig­ure 3: Cracks (%) com­par­i­son of stan­dard ver­sus split fed birds

Fig­ure 1: Pro­duc­tion com­par­i­son of stan­dard ver­sus split fed birds

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