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Altering poultry sex ratios

Kamis, 10 September 2009 1 komentar

Chickens, like most animals, typically produce equal numbers of males and females. But this natural sex ratio doesn’t always work in the poultry industry’s economic favor. A University of Georgia researcher is working on ways to skew the chicken’s sex ratio to help the industry streamline production and make more money.

Chickens are big business in Georgia, worth $4.9 bln in 2008, or 41% of the state’s total agricultural value. For the broiler sector of the poultry industry, the females are less profitable. On average, male broilers weigh half a pound more than females at market age, and they eat 5% less feed. However, in the egg-laying sector, the females are prized over males, obviously, because males can’t grow up to produce eggs.

Kristen Navara, a poultry scientist with the UGA College of Agricultural and Environmental Sciences, is trying to determine how to control avian sex ratios.

“In nature, it is a necessary strategy to adjust offspring sex in relation to the environment,” she said. “Humans, rodents, birds all skew sex ratios. It is clear females need the ability to adjust offspring for the environment where they will be born or hatched into.”

Navara has recently studied skewed sex ratios in hamsters and humans in relation to day length. She is now looking for the mechanism that can control the ratios in poultry and finches. She’s using hormones, particularly corticosterone, to find that mechanism.

Injecting female birds with a burst of corticosterone just before ovulation produced a sex ratio skewed toward males, or 81%. She believes she can flip the ratio to favour males or females using hormones or aggravates, which stop the secretion of corticosterone.

Sara Beth Pinson, a graduate student in Navara’s lab, is coordinating studies to determine the optimal dose of corticosterone to produce the desired result. They are also testing different durations of the hormone treatment to determine how long-term treatments affect offspring sex. Research results could be available in 6 months.

This research “is something the industry has been looking for for years,” said Mike Lacy, head of the CAES poultry science department. “The US poultry and egg industry funded Dr. Navara to do this research because it is something the industry is very interested in.”

It is important to note that no chickens used for food are given hormones. Navara’s research is only using hormones to discover the mechanism. “Broilers are not treated with hormones. “So far, the hormone injections seem to work, but what we want to do is find the mechanism the hormone is working through and then produce a non-hormonal treatment for the birds. That is the optimal way to go,” she said.

PUBLICATION DATE:  08/11/2009

SOURCE:  WorldPoutry.net

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Kategori:Perkuliahan

Brooding and rearing baby chicks

Kamis, 9 Juli 2009 1 komentar

Baby chicks are really quite easy to raise. With a few pieces of equipment and a small place to put them, success in brooding and rearing is virtually assured. During this period of the bird’s life, the most important needs are for warmth, protection, feed, and water. When growing chicks of any species-chickens, turkeys, pheasants, or almost any other production bird-each of these aspects must be considered.

Natural vs. artificial brooding

In nature, chicks hatch after 2 to 4 weeks of incubation by the parents, most often the hen. The hatched chicks provide the stimulus to the hen to change her work from incubating eggs to brooding young. This form of brooding chicks is the easiest if only a few chicks are raised because the mother hen does all the work.

Hens that are “good mothers” include Rhode Island Red, New Hampshire, Plymouth Rock, Cochins, and Silkies. Under natural brooding, chicks can easily be fostered under a broody hen at night, and she will raise them as her own even if they are pheasants, turkeys, quail, or waterfowl.

When broody hens are not available, or large numbers of chicks are to be raised, artificial brooding is necessary. Chicks will perform equally well under artificial or natural brooding, providing they are precocial; that is, able to walk and feed themselves within hours of hatching, as baby chickens are.

Novice growers are not advised to try artificial brooding for altricial chicks; that is, chicks such as pigeons, doves, finches, and parrots that remain in the nest to be cared for and fed by the parents. Many of these chicks are naked, blind, and unable to walk for several weeks after hatching and require around-the-clock care and feeding.

Baca selanjutnya…

Kategori:Perkuliahan

Pemilihan Pengawet Produk Olahan Daging

Kamis, 7 Mei 2009 27 komentar

Oleh Edi Suryanto

Untuk menghindari kerusakan, maka daging perlu diawetkan. Pengawetan daging dapat dilakukan dengan penambahan bahan pengawet yang termasuk dalam Bahan Tambahan Pangan (BTP). Namun masyarakat sekarang merasa ketakutan apabila mendengar istilah bahan pengawet atau bahan kimia yang dapat menimbulkan efek negatif bagi tubuh. Padahal, ketakutan ini tidak perlu terjadi. BTP sebenarnya adalah bahan aditif yang mengandung senyawa-senyawa kimia, misalnya natrium klorida, senyawa nitrit/nitrat, senyawa phosphate, dan lainnya yang telah diijinkan penggunaannya. Namun yang menjadi pertanyaan apa jenis pengawet yang cocok untuk produk olahan daging, bagaimana dengan keamanan dan ambang batas penggunaan, dan amankah bahan pengawet tersebut bagi kesehatan konsumen?

Bahan-bahan yang umum digunakan untuk pengawetan produk olahan daging antara lain adalah 1) garam (sodium chloride), 2) alkaline phosphates (sodium tripolyphosphate), 3) sweetener seperti dextrose, sukrosa dan sorbitol, 4) sodium atau potassium nitrite digabungkan dengan sodium atau potassium erythorbate atau ascorbate, 5) sodium laktat atau potassium lactate, 6) sodium acetate dan diacetate, 7) liquid smoke, 8) antioxidan seperti butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT) propyl gallate (PG), alpha tocopherols. Terdapat pula beberapa asam yang digunakan untuk menghambat pertumbuhan mikroorganisme pada karkas unggas. Karkas ayam yang dicelupkan dalam larutan asam laktat atau asam sitrat mempunyai masa simpan yang lebih lama.

Baca selanjutnya…

Kategori:Perkuliahan

Competitive Exclusion and Vaccination for Reduction of Salmonella Enteritidis Contamination of Eggs

Jumat, 28 November 2008 5 komentar

The Salmonella enteritidis (SE) pilot project (Schlosser et al. 1995) showed that the risk of eggs being contaminated with SE could be reduced by proper house cleanout and disinfection, rodent control, biosecurity, and by housing SE-free chicks and pullets. As a result, the focus for SE risk reduction in the commercial egg industry has been on adoption of voluntary egg quality assurance (QA) programs (e.g. the Pennsylvania and California Egg Quality Assurance Programs, and others modeled after them) which stipulate specific standards for management practices. QA programs appear to have been successful for reducing the incidence of SE in eggs in regions of the United States where SE has been a problem.

New methods for controlling SE in poultry have been developed, such as competitive exclusion of SE in the intestinal tract and SE vaccination. Presently, the number of commercial products available for either of these options is limited, but commercial offerings no doubt will increase if these approaches to SE control prove effective in the field.

Competitive exclusion (CE) cultures contain microflora that can live in the digestive tract of a chicken. In fact, these cultures are derived from intestinal samples taken from mature chickens. When established in a bird’s intestinal tract, the CE culture hinders colonization by salmonellae bacteria. One advantage of CE cultures is that they exclude many species of Salmonella, not just Salmonella enteritidis. The protection they offer is immediate. To be effective, a CE culture must be administered before a bird is exposed to salmonellae because the culture will not reliably eliminate salmonellae which already reside in the bird’s intestinal tract. Field trials have demonstrated that salmonellae contamination of processed broiler carcasses was reduced when chicks from hatcheries having low environmental levels of salmonellae were treated with a CE culture (Blankenship et al. 1993). By preventing early colonization of chicks by salmonellae, the CE culture appears to forestall buildup of the bacteria in the growing environment, leading to lower levels of contamination when flocks reach market weight. Currently, there is little published scientific data for commercial layers regarding the efficacy of CE cultures but it stands to reason that similar control of salmonellae, including SE, could be achieved during pullet growout and at other specific times in the life of a hen.

A chicken is especially vulnerable to salmonellae colonization when its digestive tract does not have an established population of normal microflora, as occurs at hatch, after administration of antibiotics, and apparently also during feed deprivation. A hen is very susceptible to SE infection during the feed withdrawal phase of an induced molt.

In environments where SE is present, competitive exclusion cultures would have their greatest potential to control SE infection of commercial layers if applied specifically at times when the flock is unusually susceptible to SE colonization. These times would be at hatch and housing, after antibiotic treatment, and perhaps during induced molt feed withdrawal and any other occasion which might cause the flock not to feed. Once mature microbial populations have been established in the gut of a chicken, CE cultures offer little additional protection against salmonellae. This may explain why in the example mentioned above, salmonellae contamination of processed broiler carcasses was not entirely eliminated in flocks treated with a CE culture. One cannot expect that CE products would give commercial layers total protection from SE.

SE vaccines operate differently than competitive exclusion products in that they cause a chicken to develop antibodies which protect it specifically against SE, as opposed to other Salmonella species. Immunization makes a bird more resistant to SE than it would otherwise be in normal circumstances, and the protection lasts for months. Protection obtained from SE vaccination develops gradually as the chicken’s immune system forms antibodies. To develop immune protection by the start of egg laying, SE vaccine must be administered to pullets during the growing period. A booster vaccination during an induced molt may also be advisable.

SE vaccination cannot guarantee total protection against SE because any immune system can be overwhelmed by high doses of an infectious agent, but field trials suggest promising reductions of SE occurrence in vaccinated flocks (Schlosser et al. 1995). SE vaccination would be particularly useful in situations where an SE population might persist after cleanout of an SE-positive house, or when an SE challenge is likely, as in an SE-positive complex where rodents can travel between houses.

Neither competitive exclusion nor SE vaccination will eliminate the need for a comprehensive egg quality assurance program because the best way to ensure that eggs do not become SE contaminated is to make sure
hens are never exposed to SE. In environments where SE might be present, both competitive exclusion and SE vaccination, properly applied, would be useful components of a QA program to minimize risk of SE contamination of eggs.

References:

Blankenship, L.C., J. S. Bailey, N.A. Cox, N.J. Stern, R. Brewer, and O. Williams, 1993. Two-step mucosal competitive exclusion flora treatment to diminish Salmonellae in commercial broiler chickens. Poultry Science 72:1667-1672.

Schlosser, W., D. Henzler, J. Mason, S. Hurd, S. Trock, W. Sischo, D. Kradel, and A. Hogue, 1995. Salmonella enteritidis Pilot Project Progress Report. U.S. Government Printing, Washington, DC.

By A. Bruce Webster, Extension Poultry Scientist
Poultry Tips newsletter – College of Agricultural and Environmental Sciences
The University of Georgia Cooperative Extension Service

PUBLICATION DATE: 11/24/2008
SOURCE: Univ. of Georgia Cooperative Extension Service
Kategori:Perkuliahan

Transporting Broiler Chickens Could Spread Antibiotic-Resistant Organisms

Jumat, 28 November 2008 3 komentar

Researchers at the Johns Hopkins Bloomberg School of Public Health have found evidence of a novel pathway for potential human exposure to antibiotic-resistant bacteria from intensively raised poultry—driving behind the trucks transporting broiler chickens from farm to slaughterhouse. A study by the Hopkins researchers found increased levels of pathogenic bacteria, both susceptible and drug-resistant, on surfaces and in the air inside cars traveling behind trucks that carry broiler chickens. The study is the first to look at exposure to antibiotic-resistant bacteria from the transportation of poultry. The findings are published in the first issue of the Journal of Infection and Public Health.

Typically, broiler chickens are transported in open crates on the back of flatbed trucks with no effective barrier to prevent release of pathogens into the environment. Previous studies have reported that these crates become contaminated with feces and bacteria.

The new study was conducted on the Delmarva Peninsula—a coastal region shared by Maryland, Delaware and Virginia, which has one of the highest densities of broiler chickens per acre in the United States. Ana M. Rule, PhD, a research associate in the Bloomberg School’s Department of Environmental Health Sciences, along with professor Ellen K. Silbergeld, PhD, and Sean L. Evans collected air and surface samples from cars driving two to three car lengths behind the poultry trucks for a distance of 17 miles. The cars were driven with both air conditioners and fans turned off and with the windows fully opened. Air samples collected inside the cars, showed increased concentrations of bacteria (including antibiotic-resistant strains) that could be inhaled. The same bacteria were also found deposited on a soda can inside the car and on the outside door handle, where they could potentially be touched.

“We were expecting to find some antibiotic-resistant organisms since it’s pretty clear that the transportation conditions for these chickens are not closed or contained,” Rule said. “Our study shows that there is a real exposure potential, especially during the summer months, when people are driving with the windows down; the summer is also a time of very heavy traffic in Delmarva by vacationers driving to the shore resorts.”

The strains of bacteria collected were found to be resistant to three antimicrobial drugs widely used to treat bacterial infections in people. These drugs are approved by the U.S. Food and Drug Administration for use as feed additives for broiler poultry. The study findings were also consistent with other studies on antibiotic resistance in poultry flocks and poultry products.

According to the authors, the findings support the need for further exposure characterization, and attention to improving methods of biosecurity in poultry production, especially for regions of high density farming such as the Delmarva Peninsula.

Support for the study came via the Johns Hopkins Center for a Livable Future’s Innovation Grant Program.

PUBLICATION DATE: 11/27/2008
SOURCE: Johns Hopkins Bloomberg School of Public Health
Kategori:Perkuliahan

Factors Affecting Egg Quality

Rabu, 8 Oktober 2008 Komentar dimatikan

Many factors affect egg quality. Sometimes the cause is not a single factor but a combination of factors. A few of these problems can be prevented or reduced by good hen management. Producers should remember that genetics, feed quality and environment play a role in egg quality. The most reliable factor is age. A young pullet produces smaller eggs with strong egg shells and albumen that stands high. As the hen ages, the shells thin, and the albumen begins to weaken and run. Hens can be molted to induce another egg cycle, which will improve egg quality, or they will need to be replaced with young pullets.

The following charts summarize factors that may affect egg quality and suggest corrective measures. As more emphasis is placed on egg quality, it is important that all possible defects be eliminated. When defects are found, consult the chart for possible causes and solutions.
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Kategori:Perkuliahan

Effect of Summer Heat Stress on Poultry Breeding Stock

Minggu, 28 September 2008 Komentar dimatikan

As the hot summer months approach producers´ attention is turned to management methods designed to maintain productivity during elevated ambient temperatures. For broiler and turkey meat producers, getting the birds to continue eating and efficiently converting their feed source to weight gain is the overall objective. The effects of heat stress have been well documented in relation to feed consumption, weight gain and house efficiency in broilers. In extreme heat situations, keeping birds alive becomes the most critical element, especially in older meat-type birds.

For producers of broiler breeders, the volume of feed the birds consume is restricted, so even during elevated temperatures the birds will often still consume the feed provided to them. This is especially true for broiler breeder males that will generally eat all the feed provided them in less than an hour during both summer and winter months. During this time of the year, however, the birds´ energy needs are reduced, and therefore, they do not require as much feed for maintenance as they do during the winter months. The problem with breeders is maintaining egg production, fertility, hatchability and ultimately the number of quality chicks produced. We, as an industry, have come a long way in the utilization of quality equipment in the breeder houses and therefore in reducing in house temperature spikes. Twenty years ago it was estimated that there was an average 15% drop in fertility in broiler breeders during the summer months. Due to improvements in housing, the reductions in fertility due to heat stress may not be so dramatic today. Nevertheless, the industry generally sees the lowest fertility and hatchability during the hot summer months. Baca selanjutnya…

Kategori:Perkuliahan