Op­ti­mis­ing eggs in hot weather

Plan­ning ahead for op­ti­mal re­sults

The Poultry Bulletin - - CONTENTS -

With Spring fast ap­proach­ing and tem­per­a­tures et to rise, every time the sea­son changes, the same thing hap­pens. Hot weather hits sud­denly, layer feed con­sump­tion drops, and pro­duc­tion and egg size suf­fer as a re­sult. It’s a pre­dictable se­quence of events, yet we sel­dom plan ahead for avoid­ing these con­se­quences.

The most se­verely af­fected flocks are those just com­ing into pro­duc­tion when the hot weather ar­rives. That is a pre­car­i­ous time in the life of a layer any­way, be­cause they have dif­fi­culty con­sum­ing suf­fi­cient feed to meet their nu­tri­tional de­mands, even in nor­mal con­di­tions. Adding the ef­fect of heat stress at this time can only make it worse. What are some ac­tions that can be taken to bet­ter pre­pare young flocks to main­tain pro­duc­tion and egg size dur­ing hot weather?

Body Weights

The sin­gle most im­por­tant fac­tor for achiev­ing

egg weight is the pul­let’s body weight ma­tu­rity. This re­la­tion­ship, is sum­marised in the ta­ble be­low.

For every 45 g heav­ier the av­er­age body weight at 18 weeks, egg size in­creased al­most 0.5 grams. Of course, body weight is af­fected by many man­age­ment fac­tors, in­clud­ing disease, light­ing, space al­lot­ment, and beak trim­ming, but the most di­rect in­flu­ence prob­a­bly comes from nu­tri­tion.

It has been demon­strated that pul­let growth is most re­spon­sive to pro­tein in roughly the first half of the grow­ing pe­riod and to en­ergy in the later half. We have learned that en­ergy in­take can be the most re­stric­tive nu­tri­ent lim­it­ing growth. With to­day’s feed ef­fi­cient va­ri­eties, we

some­times need to en­cour­age con­sump­tion dur­ing grow­ing by keep­ing house tem­per­a­tures a lit­tle cooler, run­ning feed­ers more of­ten, and al­low­ing more space per bird. Also, higher den­sity di­ets, es­pe­cially en­ergy, will al­low the pul­lets to con­sume ad­e­quate en­ergy and other nu­tri­ents on a lower level of feed in­take.

Rate of ma­tu­rity

An­other way to im­prove body weights at ma­tu­rity is by de­lay­ing ma­tu­rity. Ge­netic se­lec­tion has been ad­vanc­ing the rate of sex­ual ma­tu­rity by about one day per year. Early ma­tu­rity can be a valu­able trait if the nec­es­sary body weight can also be at­tained. How­ever, if at least stan­dard body weight is not present at 18 weeks,

light stim­u­la­tion should be de­layed un­til that tar­get weight is achieved. A more ef­fec­tive ap­proach to pur­posely de­lay ma­tu­rity and in­crease egg size is to use a step­down light­ing pro­gram dur­ing grow­ing.

A test com­pared a con­trol light­ing pro­gram of a con­stant eight hour day length from three to 16 weeks and stim­u­la­tion be­gin­ning at 17 weeks to a de­lay-type pro­gram with step-down light­ing from eight to 13 weeks and stim­u­la­tion be­gin­ning at 19 weeks. Pro­duc­tion was de­layed in the step-down pro­gram by 10 to 11 days, and egg num­bers were re­duced by seven to eight per hen-day.

The ad­van­tage was that av­er­age egg weight for 52 weeks of pro­duc­tion was in­creased by 1.7 grams and 1.5 grams for white and brown re­spec­tively. To­tal egg mass was not sig­nif­i­cantly dif­fer­ent be­tween the two light­ing pro­grams. This demon­strates that pro­duc­ers can use light­ing to achieve their ob­jec­tive, ei­ther more eggs of a smaller size or fewer eggs of a larger size.

An­other newer method for de­lay­ing ma­tu­rity and im­prov­ing early egg size is the “pre-lay pause.” With this tech­nique, feed is with­drawn for five days when the flock reaches 10% pro­duc­tion. In field tri­als at the Uni­ver­sity of Ge­or­gia, Charles Strong found that egg weight im­proved 0.7 to 1.5 grams per egg in the first half of the lay­ing cy­cle and only two eggs per hen housed were lost by the de­lay in ma­tu­rity. This man­age­ment tech­nique seems to be gain­ing in pop­u­lar­ity. Some method of de­lay­ing ma­tu­rity, ei­ther step-down light­ing or a pre-lay pause, should be con­sid­ered for spring-grown pul­lets to coun­ter­act the nat­u­rally in­creas­ing day length, and to im­prove egg size dur­ing the en­su­ing hot sum­mer months.

Nu­tri­tion in early lay

Egg size in early lay seems to be nu­tri­tion­ally in­flu­enced most by di­etary pro­tein and fat lev­els. Don Bell and Ralph Ernst re­ported that one ex­cep­tional layer flock in their state main­tained egg size 6.3 to 7.5 grams per egg above breeder stan­dards from 18 to 40 weeks by feed­ing about 30% higher me­thio­n­ine and 15% higher me­thio­n­ine + cys­tine lev­els than rec­om­mended by the breeder.

Kavous Ke­shavarz of Cor­nell has re­ported that in light­weight pul­lets, in­creas­ing crude pro­tein from 17% to 22% in­creased egg weight about 1.0 grams. Also, us­ing 3-4% fat to re­place an equal num­ber of calo­ries from car­bo­hy­drate in­creased egg size about 1.0 grams. The two ef­fects of pro­tein and fat seem to be ad­di­tive, so they can be used to­gether for max­i­mum re­sponse.

Veg­etable oils, or blends con­tain­ing veg­etable oil, con­tain high lev­els of linoleic acid which is es­pe­cially ben­e­fi­cial for im­prov­ing egg size. Wil­liam Mck­ean re­ported that a daily in­take of 1100 mg linoleic acid per hen per day op­ti­mised egg size and pro­duc­tion. Re­search at the Harper Adams Col­lege in the United King­dom demon­strated about a 1.0 gram larger egg size from a diet con­tain­ing 3.0% linoleic acid com­pared to 1.5%.

Stim­u­lat­ing con­sump­tion

Be­sides in­creas­ing the nu­tri­ent den­sity of the feed, any­thing we can do to stim­u­late con­sump­tion dur­ing this time will be help­ful. Feed­ers should be run fre­quently to keep feed read­ily avail­able and to stim­u­late the birds to get up to eat. Hourly runs to stir the feed are help­ful. House tem­per­a­tures should be kept cooler (2124°C.) in early lay com­pared to later in lay (24-29°C.). Dur­ing heat stress, the house should be cooled as much as pos­si­ble at night to al­low the birds to tem­po­rar­ily re­cover and lower their body tem­per­a­ture. More of the ar­ti­fi­cial light­ing should be given dur­ing the cooler hours of the day. A sup­ply of cool water will help keep the birds cool and stim­u­late more feed con­sump­tion. Also, keep­ing the air mov­ing with fans in­side the house will help the birds stay com­fort­able by re­mov­ing the hottest air next to their bod­ies (wind-chill ef­fect).

Feed that is too high in cal­cium early in lay may pose palata­bil­ity prob­lems and cause the birds to re­duce con­sump­tion. We rec­om­mend keep­ing cal­cium no higher than 3.85% prior to peak, un­less palata­bil­ity can be im­proved by us­ing meat and bone meal or fat in the ra­tion.

Con­clu­sion

It is ob­vi­ous that egg size is man­age­able through con­trol­ling body weight, rate of ma­tu­rity, and nu­tri­tion. Now is the time to plan ahead for hot weather peak­ing flocks to im­prove early egg size and op­ti­mise prof­itabil­ity.¡

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