{"id":52498,"date":"2020-08-25T13:59:01","date_gmt":"2020-08-25T11:59:01","guid":{"rendered":"https:\/\/lohmann-breeders.com\/management-of-laying-hens-under-tropical-conditions-begins-during-the-rearing-period\/"},"modified":"2020-08-25T13:59:01","modified_gmt":"2020-08-25T11:59:01","slug":"management-of-laying-hens-under-tropical-conditions-begins-during-the-rearing-period","status":"publish","type":"post","link":"https:\/\/lohmann-breeders.com\/zh-hans\/management-of-laying-hens-under-tropical-conditions-begins-during-the-rearing-period\/","title":{"rendered":"Management of Laying Hens under Tropical Conditions Begins During the Rearing Period"},"content":{"rendered":"
Environmental temperatures play a major role in the optimal rearing of layer pullets, the basis of a financially\r\nsuccessful production period of the layer bird. The optimal temperature for a white layer is 23 degrees celcius,\r\nrespectively, 24 degrees for brown layers. Every degree Celsius above this level will cause reduced feed intake and\r\nas a result, a decrease in egg numbers, shell quality and egg size. This problem can easiesily be solved by housing\r\nthe birds in an environmentally controlled house with optimal temperature. Due to lack of infrastructure such\r\nas electricity or financial means, many farmers in hot climates cannot provide such a solution and need to rely\r\non feeding techniques and special feed formulations, lighting programs such as midnight snack as well as water\r\nquality and temperature to achieve a satisfying production. Feeding techniques help the bird to eat at optimal\r\ntimes during the day, feed formulations ensure that the hens are supplied with all the required nutrients, midnight snacks, provide extra time for feeding during the coolest period of the day and optimal water temperatures\r\nensure the birds are able to reduce their body temperatures and maintain their appetite.<\/blockquote>\r\n\r\n

\r\n\r\n\r\nChickens originated from the jungles of Southeast Asia some 10,000\r\nyears ago, and the earliest known\r\ndomestication occurred in Northern China\r\n8,000 B.C. as determined from archaeological chicken bones (Lawler, 2015). From\r\nhere on, poultry production has spread\r\nworldwide with the first industrialization\r\nin the Northern hemisphere with cool and\r\nmoderate climates. Nowadays, the industry is continuously navigating back and\r\nforth between Asia and the Southern part\r\nof the world as a result of increasing populations in Asia, Africa and South America in\r\ncombination with declining birthrates as\r\nwell as strict animal right laws in Western\r\ncountries. Asia today accounts for 54.6% of\r\nthe world poultry population, followed by\r\nthe American continent with 26% and Africa with 8.2%. This means the production of\r\npoultry meat and eggs is in hot climates.\r\nIn order to facilitate cost effective egg\r\nproduction in these challenging environments, special management strategies\r\nhave to be applied. Poultry scientists have\r\nreported results of their own experiments\r\nand reviewed the available literature during the last decades which help to understand the needs of hens under heat\r\nchallenge. This article is focused on the\r\napplication of these results in practice.

\r\n\r\n
\"\"<\/div>\r\n\r\nSufficient body weight at onset of lay<\/strong>

\r\nThe basis of good egg production is a successful rearing phase, at the end of which,\r\nthe hen should have reached her standard\r\nbody weight with a well-developed frame\r\nand corresponding appetite or feed intake\r\ncapacity. Already about 50 years ago, Payne (1966) compared pullets reared from\r\n6 to 21 weeks of age in environments of\r\n20\u00b0C vs. 33\u00b0C. The birds reared at 33\u00b0C were\r\n118g lighter at 21 weeks of age and their\r\neggs consistently smaller throughout the\r\nlaying period than the group reared at\r\n20\u00b0C. The response of feed consumption\r\nto increasing ambient temperature and\r\nits effect on later performance is shown\r\nin tables 1 and 2. Pullet body weight plays\r\nan important role in egg production, and\r\nI recommend to target 10% higher body\r\nweight in hot climates than the weight\r\nstandards published by primary breeders\r\nfor moderate climates. Heavier hens will\r\nconsume more feed which will result in\r\nhigher peaks, better persistency and bet

\r\n\r\nTable 1: Decrease of daily feed consumption of growing pullets with increasing house temperature.\r\nSource: Bell and Weaver (2002)<\/em>\r\n\r\n\r\n\"\"

\r\nter resistance to heat stress and diseases.\r\nTwelve week weights are reliable predictors of 20 weeks weights, that is: pullets\r\nthat are below breed standard at 12 weeks\r\nof age will remain low at 20 weeks, whereas a pullet which is heavy in 12 weeks\r\nof age will be heavy at 20 weeks of age.\r\nTherefore special attention should be focused on pullet weight development to\r\n12 weeks of age

\r\nI have found it useful and strongly recommend to separate the birds into 2-3\r\ngroups on bodyweight as early as possible and then adjust the feed composition\/\r\nphasing accordingly so that underweight\r\nbirds have a better chance to catch up in\r\ntheir development before sexual maturity.\r\nThe first 8 weeks are critical for the skeletal development of the bird and therefore\r\nthe base of a well developed hen. Smaller\r\nbirds will have the chance of growing according to the standard without having to\r\ncompete with larger and more dominant\r\nbirds resulting in a more uniform flock\r\nin production. Later in the phase of 9-16\r\nweeks, the hen can be trained in high feed\r\nintake capacity due to the less dense developer feed without risking of running\r\ninto problems with bodyweights at the\r\nend of rearing. Transfer to the laying house\r\n(with higher light intensity!) can then also\r\nbe organized stepwise according to development. This will help to minimize the risk\r\nof prolaps and cannibalism due to overstimulation of underweight pullets.

\r\n\r\nAdditional space to minimize heat\r\nstress<\/strong>

\r\nIf the birds are placed in naturally ventilated houses, it is better to start with 10%\r\nfewer chicks for a given space than during\r\nnormal temperature conditions. This will\r\ngive the chicks more floor space and better ventilation between the chicks as well\r\nas more water and feed space. Increased\r\ndensity of hens in cage or on floor increases effects of heat stress, i.e. reduced egg\r\nproduction due to reduced feed intake,\r\nincreased feed requirement due to heat\r\nstress and increased mortality. Resear-

\r\n\r\nTable 2: Decrease of feed intake with increasing house temperature and availability of ME for egg\r\nproduction.\r\nSource: Smith and Oliver (1972), cited by Balnave and Brake (2005)<\/em>

\r\n\r\n\r\n\"\"

\r\n\r\n\r\nchers at North Carolina State University\r\nrecommend 460 cm\u00b2 per bird in hot climates in fan ventilated houses and even\r\nmore space when only natural ventilation\r\nis available. Adams and Craig (1984) compared feed intake and egg production\r\nat densities of 516, 378 and 310 cm\u00b2 per\r\nbird in conventional laying cages. Increasing space from 310 to 378 cm\u00b2 per bird\r\nresulted in 16.6 more eggs per bird for\r\nthe cost of 1.9 g feed\/hen\/day. Increasing\r\nspace from 387 to 516 cm\u00b2 resulted in 7.8\r\nmore eggs\/hen housed, 4.3 g per hen\/day\r\nhigher feed consumption and 2.8% lower\r\nmortality.

When day-old chicks are housed in\r\nfloor systems, plastic foils or paper will\r\nhelp them to find feed and water. In cage\r\nsystems, the use of extra direct light in the\r\ncages such as LED tubes (like those used\r\nfor Christmas decoration), will help the\r\nchicks to find water and feed quickly.\r\nIt is absolutely essential that the chicks\r\nreach their normal body temperature of 40-\r\n41\u00b0C as fast as possible after housing. Ideally,\r\nthis should be checked with an ear thermometer a couple of hours after placement. If\r\nthe body temperature is below 40\u00b0C, the\r\nhouse temperature has to be increased by\r\nall means. Make sure that the air humidity\r\ndoes not drop to below 70% as a result of\r\nheating. The effect of ambient temperature\r\non feed intake of laying hens (in ME), heat\r\nproduction and availability of ME for egg\r\nproduction is illustrated in table 2.

\r\n\r\n\r\nLighting Program<\/strong>

\r\nStarting chicks on a lighting program with\r\n4 hours light and 2 hours darkness on alternate, has shown improved uniformity\r\nand reduced mortality as compared to\r\nconventional lighting with 16 hours light\r\nand 8 hours darkness. This program can be\r\nused for the first 10 days and then changed to conventional lighting programs as\r\nrecommended by the breeder, possibly\r\nwith a \u201cmidnight flash\u201d to stimulate additional activity and feed intake. Leeson, Caston and Summers (2003) conducted tests\r\nin which growing pullets received different midnight light treatments, one group\r\ngrown in 8 h of light, the other in 12 h of\r\nlight. The groups given a midnight light of\r\n2 hours from 0-18 or 4-18 weeks produced\r\nthe highest number of eggs to 70 weeks\r\nof age. Introducing a midnight flash late\r\nin the rearing period, however, after 12\r\nweeks of age, resulted in pre-mature onset\r\nof lay, with the well-known risks of prolapse, cannibalism and negative effects on\r\npersistency of egg production. Practical\r\nexperience, especially with Leghorns, indicates that 1 to 1.5 h light around midnight\r\nhas positive effects on feed intake and\r\nweight gain (figure 1)

\r\n Extra lighting around midnight (Fig. 1)\r\nhas the advantage of giving the birds additional feeding time during cooler parts\r\nof the night and does not disturb the lighting program, as long as at least 3 hours of\r\ndarkness are provided before and after the\r\nextra light period. A similar program can\r\nbe used during the laying period.

\r\n\r\nHeat production of the body is higher\r\nduring light periods and abdominal temperature declines with reduction of light

\r\n\r\nFig. 1: Midnight snack: lighting during cool hours of the night to stimulate additional feed intake.\r\nSource: Lohmann Tierzucht Management Guide<\/em>\r\n\r\n\"\"

\r\n\r\n\r\nintensity. Several recommendations for\r\ndifferent lighting programs can be found\r\nin literature. Nishibri (1998) recommended\r\na \u201creversed lighting program\u201d, with light\r\nduring the cooler time from 6 p.m. to 6\r\na.m. instead of during the hot hours of the\r\nday, when the birds should rest to minimize heat stress. With this program, the hens\r\nproduced significantly more eggs than\r\nwith daytime feeding

\r\n\r\nwith daytime feeding.\r\nTo apply this idea under commercial\r\nconditions would require investment in\r\nlight proof houses, and the extra cost and\r\ninconvenience for staff working in night\r\nshifts as well as energy cost, have to be justified by higher egg output and enhanced\r\nbird welfare.

\r\n\r\nPurina Mills Inc. recommended \u201cbiomittent\u201d lighting for pullets based on the\r\nidea that better body weights can be\r\nachieved due to less activity and better\r\nfeed utilization.

\r\n\r\nThe light program is as follows: 24hrs\r\nlight during the 1st week, at 2 weeks of\r\nage the light is reduced to 8h daily and\r\nfrom 3-18 weeks lights are maintained at\r\n8hrs daily with an alternating program of\r\n15 min light\/45 min darkness, except for\r\nthe last hour of the day when the light\r\npattern is 15 min light – 30 min dark \u2013 15\r\nmin light. Ernst (1987) concluded from his\r\ntests that intermittent lighting (2 h dark \u2013 4\r\nh light) for pullets between 2 to 20 weeks\r\nshow improved weights.

\r\n\r\nrearing should provide the pullets with\r\nenough light in order to achieve the target\r\nbody weight and eating capacities. Heat\r\nproduction of the body increases with\r\nfeed intake. Therefore, it is recommended\r\nto start the lights early in the morning in\r\norder to use the cooler parts of the day for\r\nfeeding and avoid digestion of the feed\r\nduring the hot daytime. Since light intensity also increases body temperature, the\r\nhouse should be kept as dark as possible\r\nto avoid heat stress for the birds

\r\n\r\nWater<\/strong>

\r\nEnvironmental temperature is the most\r\nimportant factor for determining water\r\nintake, as illustrated in Fig. 2. Leghorn\r\npullets drink at least twice as much per\r\nday at 38\u00b0C as compared to 21\u00b0C house\r\ntemperature, whilst water temperatures\r\nbelow 21\u00b0C do not influence the water\r\nintake. Most authors agree that the optimum water temperature is about 23\u00b0C. A\r\ncommon challenge in hot climate areas is\r\nto provide sufficient drinking water at optimal temperature for all birds at all times.\r\nWater intake is the key to good feed intake,\r\nespecially in hot climates.

\r\n\r\nThe water temperature should never\r\nexceed the body temperature of the birds.\r\nTests have shown that feed intake is reduced if water temperature exceeds 35\u00b0C,\r\nand drinking water of 35-40\u00b0C has significant detrimental effects on performance.\r\nTherefore, the farm management has to\r\ndo everything possible to offer cool water\r\nto birds in rearing as well as in production. Possibilities are plenty, from regularly\r\nflushing the water lines or emptying the\r\nbell drinkers, insulating water tanks and lines (also in the house) to adding ice cubes\r\ninto water tanks or even installing chillers\r\nfor drinking water, depending on the sophistication of the farm

\r\n\r\nThe water systems should be the same\r\nin the rearing and production house to assure that the pullets find water immediately after transfer. If a loss in appetite and\r\nfeed consumption, perhaps also increased\r\nmortality, is observed after transfer, a common reason for this is that some birds take\r\ntoo long to find water and therefore stop\r\neating. Especially in this stressful transition\r\nperiod the birds need to maintain their appetite in order to cope with the challenge\r\nof sexual maturity and first egg production,\r\nwhile continuing to gain body weight.

\r\n\r\nThe maximum daily water consumption\r\nis at 6-7 weeks of production which is also\r\npeak production. Stress can increase vitamin\r\nneeds in hot climates, especially A, C and E.\r\nIn hot and humid areas, vitamin stability is\r\nreduced. Therefore it is good practice to offer vitamins in drinking water 3 days before\r\nmoving the birds and electrolytes for another 3 days after the move. Pullets should\r\nnot be serviced or moved in the hot part of\r\nthe day, preferably at night; 30% less pullets\r\nper crate than recommended for cool days\r\nshould be placed for the transport.

\r\n\r\nIn-line filters should be checked and\r\ncleaned on a regular basis and replaced\r\noften. Functional pressure gauges on both\r\nsides of the filter are an advantage and a\r\n3-8 lb differential between incoming and\r\noutgoing water pressure should be maintained. The water pressure at the end of\r\nthe line has to be checked daily to assure\r\nthat also the hens at the end of the building receive sufficient water.

\r\n\r\n\r\nUnderground water supplies are very\r\ncommon in many countries in the hot\r\nregions of the world. Water from the well\r\noften has inferior quality compared to city\r\nwater and can have negative effects on

\r\n\r\n\"\"

\r\nFigure 2: Water consumption of growing pullets as a function of house temperature\r\nSource: Daghir (2008)<\/em>

\r\n\r\nthe performance of growing pullets and\r\nlaying hens. Well water must therefore be\r\nchecked regularly in a competent laboratory for bacteria and internal quality. Saline\r\nwater may be a contributing factor if shell\r\nquality, especially of older hens, persistency of egg performance, feed intake and\/\r\nor egg weight are below the breeder\u2019s\r\nstandard. In this case, the feed formulation\r\nmust be adjusted, with a lower salt level\r\nin the feed according to the saline level of\r\nthe water.

\r\n\r\nDifferent additives in water have\r\nshown positive effects to reduce heat\r\nstress of layers. For example, birds given\r\ncarbonated water at times of temperatures\r\naround 35\u00b0C were able to maintain shell\r\nquality much better than the control (Daghir 2008). Vitamin C improves performance\r\nin hot weather, with only 100 ppm ascorbic acid. Best results were achieved with\r\nprotected ascorbic acid (e.g. Cuxavit C50)\r\nand the phosphate ester. Flocks receiving\r\nextra vitamins and electrolyte water additives during heat periods had a smaller drop\r\nin production and recovered sooner. Sodium zeolite in water can also be beneficial\r\nin reducing effects of heat stress in layers.\r\nWhy it is successful is not fully understood;\r\nperhaps it acts as a buffer in the gut and\r\nreduces alkalosis associated with panting

\r\n\r\nFeed intake and adjusted composition<\/strong>

\r\n\r\nHouse temperature is the most important factor in feed consumption of layers. \r\nMaintenance requirement in Leghorn and\r\nBrown birds is reduced by 30 kcal\/day when\r\nthe ambient temperature rises from 21 to\r\n38\u00b0C. It reaches a low at 28\u00b0C and increases\r\nwith rising environmental temperature due\r\nto the cooling energy required by the hen.\r\nAbove 28\u00b0C feed intake decreases. The average loss in energy intake is 1.6% per 1\u00b0C\r\nas environmental temperatures increase\r\nabove 20\u00b0C. As such, the bird might easily\r\nrun into a nutrient deficit resulting in low\r\nperformance. The maximum energy available for production is at 23\u00b0C for brown birds\r\nand 24\u00b0C for White Leghorns.

\r\n\r\nIt is essential to monitor feed consumption on a daily base so that energy levels as well as feed density can be adjusted\r\nto daily feed intake. Alternatively, stimulation for feed intake has to be intensified\r\nwith a reduction of energy and density of\r\nthe feed such as turning of the feed chain\r\nor shaking of the feeders can. Tadtiyanant\r\net al. (1991) concluded from several tests\r\nwith wet feed that birds had 38% more dry\r\nmatter intake compared with dry feed at 33\u00b0C. Sprayers can be installed on top of\r\nfeed chains or water can be added and\r\nmixed with feed manually, depending on\r\nthe level of the management.

\r\n\r\nUse of high energy layer rations is recommended in hot climates. Fat adds energy to the diet and stimulates feed intake\r\nand therefore, ME intake. Many feed mills\r\nin hot climates have a problem providing\r\ngood feed structure and often end up\r\nproducing fine and dusty feed. Adding oil\r\nimproves the palatability of the feed and\r\nmaking it easier for the hen to eat enough.\r\nOil also has less heat increment produced\r\nduring digestion which reduces the heat\r\nstress on the bird. Adding 5% fat does\r\nnot only improve feed intake but also egg\r\nweight and shell thickness. In tests conducted in Malaysia it was shown, that when\r\nfree to choose, hens tend to consume\r\nmore feed with supplemental fat than oil\r\nfree feed. Sohail et al. (2002) observed that\r\nmaximum profits were obtained when fat\r\nis added to the highest protein diet (19.8%)\r\nfrom 21 to 37 weeks of age, but special care\r\nhas to be taken to avoid oxidation.

\r\n\r\nFeed intake decreases not only when\r\ntemperatures rise but also when energy\r\nis increased in the feed. Peguri and Coon\r\n(1991) found that feed intake was 5-9 g lower when ME was increased from 2645 to\r\n2976 kcal\/kg and was 217 g lower when\r\ntemperatures were increased from 16 to\r\n31.1\u00b0C. Egg weight increased when feed\r\nenergy was increased from 2645 to 2976\r\nkcal\/kg and decreased when temperatures increased from 16.1 to 31.1\u00b0C. More expensive feed can, in the end, save money\r\ndue to lower feed quantities.

\r\n\r\n\r\nProtein requirement is not affected by

\r\n\r\nTable 3: Recommended Structure of Calcium in Different Types of Layer Feed.\r\nSource:Lohmann Tierzucht Management Guide<\/em>

\r\n\r\n\r\n\"\"

\r\n\r\n\r\n\r\n
\"\"<\/div>\r\n\r\n\r\n\r\n\"\"

\r\n\r\nFigure 3: Growing summary of LOHMANN BROWN PS flock in tanzania open houses, hot climate<\/em>

\r\n\r\ntemperature, but it is common knowledge\r\nnowadays that protein and amino acid\r\nrich diets are essential in hot climates to\r\nensure the same daily intake of these nutrients as would be consumed at 21\u00b0C. De Andrande et al. (1977) fed laying hens under\r\nheat stress, a diet containing 25% more of\r\nall nutrients except energy, which was only\r\nincreased by 10%. He observed that with\r\nthis kind of feed, the hen overcame most\r\nof the detrimental effects of high temperature on percentage, egg production and\r\negg weight. A daily intake of 360 mg of methionine should be obtained because small\r\neggs can be a result of low energy intake\r\nbut also low amino acid intake. The decrease of egg weight for every 1\u00b0C rise in temperature has been estimated between 0.07\r\nto 0.98 g per egg. Daily linoleic acid intake\r\nshould be at least 2g per bird, best to be\r\nachieved by fat. High temperatures increase respiratory rate, resulting in respiratory\r\nalkalosis, which alters acid-base balance\r\nand blood pH. Adding sodium bicarbonate\r\nto feed and carbonated water can help.

\r\n\r\n\r\n Excessive calcium can have negative\r\neffects on feed intake due to physiological\r\neffect of appetite and reduced palpability\r\nof the feed. Feed intake of laying hens may\r\ndecrease as a result of excessive levels of\r\nfine calcium in the diet. Devegowda (1992)\r\nreported that in India, feeding calcium\r\nseparately with a diet of only 2% calcium\r\nimproves feed intake, egg production and\r\nshell quality. Since the calcium requirement of a layer in peak production is about\r\n4.1 g and increases to 4.5 g with age, the\r\nmissing 1.9-2.2% calcium should be offered ad lib as coarse calcium on top of the\r\nfeed for cage management or in extra containers for floor and aviary systems, so each\r\nhen can consume it according to her needs\r\n(table 3). Main demand for calcium is in the\r\nafternoon and evening hours. If separate\r\ncalcium feeding is not possible, at least\r\n50% of the calcium in a ration should be\r\ngiven in coarse particles rather than all the\r\ncalcium in powder form. This ensures that\r\nthe calcium is not completely digested before the early hours of the morning when\r\nthe hen needs it for egg shell production.\r\nA \u201dmidnight snack\u201d not only improves feed\r\nintake but also reduces stress on the hens\r\ndue to an extra calcium intake at the time\r\nthe organism requires the supply.

\r\n\r\nPhase feeding<\/strong>

\r\nIt is recommended to supply feed twice a\r\nday, with 1\/3 of the feed in the morning\r\nand 2\/3 in the afternoon, leaving the feeders empty for a max. of 1 hour a day during the hottest hours. This stimulates feed\r\nintake, ensures that also the fine parts of\r\nthe feed are consumed and prevents molding of the feed. Pre-layer feed is a must\r\nand should be offered 2-3 weeks before\r\negg production when liver and reproductive organs are increasing in size and at\r\nthe same time calcium reserves are built\r\nup to meet demands of shell production.\r\nIt should be given for about 10 days and\r\nnot more than 1kg per bird. The hens can\r\nget adjusted to the higher amount of calcium of the feed and will not lose their\r\nappetite when given layer phase one feed\r\ncontaining normally 3.9% calcium. Early introduction of high calcium levels in\r\nlayer diets have often shown to increase\r\nwet manure, and the use of pre-layer feed\r\nshould also help to minimize this problem.\r\n Studies have shown that laying hens\r\nare able to survive heat stress periods better if they have been exposed to a daily, intermittent heat-stress situation. Therefore,\r\n\r\n\"\"

\r\n\r\nFigure 4: Production summary of LOHMANN BROWN PS flock in tanzania open houses, hot climate<\/em>

\r\n\r\nit may be considered to allow rearing birds\r\nto be exposed to temperatures of 29-33\u00b0C\r\nbefore laying period even if it would be\r\npossible to keep the environmental temperature below this level with the help of\r\nthe house system. White Leghorns are not\r\nnecessarily more heat-tolerant than brown\r\nstrains, as assumed many years ago. It is recommended not to remove combs and\r\nwattles as these organs are used to help\r\ncool the body. Birds can also wet them\r\nwith the offered drinking water, either\r\nin bell drinkers or nipple drinkers which\r\nshould be equipped with cups.

\r\n\r\n Wet droppings can be a problem in\r\nhot climates due to the increased water\r\nintake. Layers drink more in cages than on\r\nthe floor and water intake increases with\r\nproduction. High levels of protein and salt\r\nhave shown to increase wet droppings.\r\nSodium levels in the diet should be kept\r\nat 0.18-0.16 g\/day per bird. The use of\r\nhigh amount of barley and crumbled feed\r\nmight also cause wet droppings.

\r\n\r\n\r\nField results in Tanzania<\/strong>

\r\n\r\nPaying special attention to the needs of\r\nthe birds in hot climates pays off, as illustrated in figures 3 and 4. This brown-egg\r\nparent flock suffered from a bacterial infection at 3-4 weeks of age, which unfortunately is not infrequent in open houses.\r\nHowever, after treatment, the survivors developed well. Perhaps they benefited from\r\nthe lower density and performed similar as\r\nwould be expected in moderate climates.\r\nObviously commercial chickens and parent stock of modern strains are adaptable\r\nto tropical climate and can cope well with\r\nconditions in open houses with only natural ventilation, at temperatures of up to\r\n40\u00b0C and a humidity of 60-70%.

\r\n\r\n\r\nSummary and Conclusion<\/strong>

\r\nEgg production in hot climates is a challenge for every producer, but excellent\r\nresults can be achieved without investing\r\nin expensive environment control, i.e. if\r\ngood management is applied throughout\r\nthe life of a flock, based on the results of\r\npoultry research and experience in practice. Layers in hot climates need more space\r\nin rearing and in production. Different\r\nlighting programs can help to achieve\r\nthe standard body weight even in heat\r\nstress. A midnight snack enables the birds \r\nto consume feed in the cool parts of the\r\nday and will provide them with calcium for\r\nthe shell production in the early morning\r\nhours. Feeding coarse calcium separately\r\nto a low calcium feed will increase the feed\r\nintake and also will reduce the risk of early\r\nmortality due to cage layer fatigue. Cool\r\nwater will allow the hens to reduce their\r\nbody temperature and maintain their appetite. Adding oil and fat to the feed will\r\nmake it more palatable and therefore easier to consume as well as provide the correct amount of energy even with reduced\r\nfeed intake. Hens like humid feed, wetting\r\nthe feed will help to increase feed intake\r\nin hot climates. Birds can get adjusted to\r\nhot climates and can be trained via intermittent hot periods in the rearing to withstand heat stress better during rearing.\r\n\r\n

\r\n\r\nViola Holik<\/em>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n","protected":false},"excerpt":{"rendered":"Environmental temperatures play a major role in the opt […]","protected":false},"author":15,"featured_media":51993,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"ngg_post_thumbnail":0,"footnotes":""},"categories":[2335],"tags":[],"class_list":["post-52498","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-poultry-news-zh-hans","issue-1-2016-zh-hans","yeararchive-2016-zh-hans"],"acf":[],"yoast_head":"Management of Laying Hens under Tropical Conditions Begins During the Rearing Period - Lohmann Breeders<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/lohmann-breeders.com\/zh-hans\/management-of-laying-hens-under-tropical-conditions-begins-during-the-rearing-period\/\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Management of Laying Hens under Tropical Conditions Begins During the Rearing Period - 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