Published by: SPESFEED cc, PO Box 48, Rivonia, 2128. Tel: (011) 803-2050, Fax: (011) 803-8201
| Inside This Issue |
This winter edition of the newsletter comes to you from a reasonably quiet industry. Although the price of most ingredients has been stable, the manner in which the maize price has rocketed is of concern.
We are sad to have to tell you that Trish Adam, our office administrator passed away on the 31st of July after a long illness. We wish her family all the best during this very difficult time. Michelle Garbers, who is a very experienced administrator, will now carry out our book keeping function and we wish her a long and happy stay at SPESFEED.
We have decided not to continue lecturing at the University of Pretoria next year for a number of reasons. Mostly though, it is not satisfactory for the students not to have their teachers close at hand in case any problems should arise. There is a likelihood that we will still run short courses at the faculty.
Morocco
I had an opportunity to visit Morocco at the invitation of the American Soybean Association - this to give lectures at the Institute of Agronomy and Veterinary Medicine Hassan II, which is the principle agricultural University in Morocco. Our group comprised members of industry from Morocco, Algeria, Tunisia and Senegal as well as personnel from the Institute itself.
The poultry and feed industries in these countries are smaller than our own but have the potential to grow fast. In Morocco for example, current broiler consumption is about 8kg/head per annum. Chicken is relatively expensive as a result of duties that have to be paid on all imported feed ingredients. There are about 6 mil layers in the country.
What struck me the most were the similarities between our industries and countries. For example, egg size is a less importance than it is in Europe and cull weight of hens is a factor to be considered.
Russia
During July I visited Russia at the invitation of Tommy Bosman (formerly MD of Delmas Kuiken), but now running Golden Rooster farms at Lipetsk some 450 km south of Moscow. I experienced the hottest weather recorded in 100 years, with daily temperatures at the 35 to 37 degree mark.
Russian meat consumption has dropped from some 80kg per capita in the early 90’s to 41 kg last year, of which 34% is poultry meat. Domestic production will grow 10% this year to some 893 000 tons, which is little more than is produced in South Africa. Large quantities of poultry meat are still imported from the US, Brazil and other countries.
Golden Rooster is a significant player in the Russian market and is actively expanding. More than half of their end production is still done in cages.
Courses
We still have the following courses scheduled for this year:
 | Dairy Nutrition September 11 to 13 |
| Pig Nutrition September 18 to 20 |
We plan to run the dairy course with the help of Dr Lourens Erasmus this year, as he is up to date on all of the latest information regarding the newly published NRC recommendations for Dairy Cattle.
Please let Christél know if you are interested in attending either course.
Aids and Consumerism
A recent study, commissioned by the National Chamber of Milling and carried out by the Bureau of Economic Research at Stellenbosch University, examined the impact that Aids will have on the milling industry. It was found that maize sales are likely to be more sensitive to population growth than wheat flour sales, which in turn are more sensitive to disposable income and unemployment rates.
A forecast of sales was then carried out to estimate the impact of Aids on population growth, disposable income and employment:
| In 2006 projected maize meal sales will be reduced by 143000 tons/year (180000 tons of maize) and by 2011 sales of maize meal will be 429000 tons less (536 000 tons of maize) than they would have been without Aids. |
| In 2006 the milling industry will use 66 000 tons less wheat and by 2011 this figure will have increased 186 000 tons than would have been used under normal circumstances. |
The question that begs asking is what will the impact of Aids be on meat, milk and egg sales, and how will this impact on the feed industry?
New Book
An important new book for all poultry nutritionists has just been published. It is the Fourth Edition of Scotts "Nutrition of the Chicken", which has been updated and re-written by Steve Leeson and John Summers. While the layout of the book is familiar the emphasis in terms of content has changed. Only 20% of the Third edition dealt with protein and energy whereas in excess of 30% of this edition is devoted to these topics. In addition there is a new chapter dealing with natural toxicants in feed.
As with the other books by these authors the book is very readable, although considerably more scientific than "Commercial Poultry Nutrition" for example, the book still contains a lot of information that is of practical relevance.
If I have any criticism of the book it lies with the index. For example Soybean meal is only indexed for the product itself and its quality assurance. However, in the text it is dealt with extensively in the chapters on digestion and protein.
All in all though, his is a book that every professional nutritionist, student and poultry farmer should have on his shelf.
Rick Kleyn
The NuTec Broiler Breeder Workshop
During June the NuTec broiler breeder day was held in Johannesburg, Stellenbosch and Pietermaritzburg. I, for one, learnt a tremendous amount, particularly from Dr Frank Robinson from the University of Alberta. Despite the good turnout at the meetings, I felt that it would be a good idea to encapsulate Frank’s talks in a few short paragraphs because what he had to say has a direct bearing on all people involved with the feeding and management of broiler breeders.
The first talk that Frank gave revolved around the photostimulation of breeding hens. Research has shown that by delaying photostimulation to 22 or 23 weeks of age can have a major impact on flock uniformity and ultimately on the number of chicks produced per breeder. This can be seen from the data shown below (Robinson et al., 1996).
Parameter |
Age at Photostimulation |
||||
|
17 wk |
18.5 wk |
20 wk |
21.5 wk |
23 wk |
Days to first egg |
50.6a |
42.3b |
34.2c |
27.9d |
24.2d |
Total eggs produced (58 wk) |
160.6 |
155.2 |
162.8 |
162.0 |
158.0 |
C.V body weight at 1st egg |
9.6 |
7.9 |
7.7 |
7.1 |
5.8 |
Hatch of Fertile (%) |
79.6a |
79.8a |
86.2a |
84.8a |
84.5a |
Chicks produced (chicks/hen) |
118.9b |
116.6b |
132.5a |
129.8a |
127.4a |
From this table it is clear that photostimulating birds earlier does not necessarily make them lay proportionally earlier. It is also clear that delaying photostimulation improves the CV (uniformity) of the flock and increases the number of hatching eggs and chicks produced because there are fewer small eggs laid and hatchability improves.
In a country such as Canada where birds are transferred from light tight rearing houses to light tight layer houses this system is possibly easy to implement. Under local conditions, moving birds from the rearing site to the breeder site automatically brings about photostimulation.
Practically we could delay transfer, or alternatively we could ensure that birds were transferred at the correct daylength. This means that if the daylength in September is 12 hours then the birds should be reared on 12 hours of light so that it would still be possible to photostimulate them 2 or 3 weeks later.
It is true that the high light intensity of our open sided houses may well play a role in photostimulation as high light intensities have been shown to reduce the days to sexual maturity.
The second important aspect of managing breeders dealt with by Frank was that of feed allocation. He has been able to show that large increases in feed allocation before coming into peak production have important commercial implications.
They result in an almost immediate increase in the lipid content of the liver. A week later there is an increase in the lipid content of the ovary. This leads to the recruitment of excessive follicles and dual regimes. Frank was able to show how this greatly increased peak production, but it also to an increase in multiple ovulation and decreased persistency of lay.
In order to make the correct feed allocations to breeders it is important to know not only the weight of the birds in the flock but also the uniformity. He believes that in the critical period going into peak and peak production itself, birds should be weighed daily (automatic scales) or at least three times a week if weighed manually. This more intense form of weighing allows for far better body weight control. Weighing once a week simply does not give one a clear idea of what is going on in the flock.
It is known that increasing or maintaining a high level of feed allocation will not lead to an increase in feed production. It is important therefore to pick up any weight changes that may result from a decline in egg production. Do not wait for a drop in egg numbers before feed withdrawal begins as this can only lead to complications during the later stages of production. When feed withdrawal begins it is essential to remove feed gradually.
The message that needs to be stressed time and time again is this-"Don’t let the bird’s metabolism know that you have changed the feed allocation". This is equally important for both increasing feed allocation prior to peak, as it is to feed withdrawal.
Frank Robinson
University of Alberta
10 Rules for Managing Growing Pigs
Around 70% of the costs during the growing period is feed related. Bearing the recent increase in feed costs in mind it is vital that this stage is managed correctly. The grower-finisher stage of pork production is the toughest to manage due to a lack of sophisticated record systems for this phase of production. The following article is based on a paper presented by Mike Brumm at the 41st George Young Swine Conference.
1. Set realistic performance goals.
|
Average result |
1989 |
1999 |
% difference |
|
ADG (g/d) |
645 |
718 |
11 |
|
FCR (kg/kg) |
3.44 |
3.09 |
10 |
|
Top 10% |
|||
|
ADG (g/d) |
732 |
832 |
14 |
|
FCR (kg/kg) |
3.30 |
2.65 |
20 |
| The table shows that the average performance has increased by more than 10% during the last 10 years. The top 10% producers have had bigger increases. |
| Some of the improvement in feed conversion may be explained by more fat in diets and the increased use of pelleted feed. As a rule of thumb, each 1 percent addition of fat to grower-finisher diets improves feed conversion 2 percent. Pelleting improves feed conversion by 6-8 percent. |
2. Use records to monitor performance.
|
Many producers fail to use record systems that monitor performance as a group of pigs grows. |
|
Instead, after-the-fact information from closeouts is used to make management adjustments for the next group. |
| An effective method to monitor pig growth is to plot feed deliveries against a pre-planned feed budget. Once a unit has a history from several groups, feed disappearance vs. expected delivery date and amount, it can monitor performance. If deliveries or intake is running ahead of the budget, either feed is being wasted or pigs are growing faster than projected. If deliveries are lagging, the reasons for a slowdown can be investigated. |
| Another useful tool is water disappearance. A sudden change in usage indicates a change in performance, often related to health. |
3. Use feed budgets to manage diets.
| Many producers make feed management decisions on estimated weights and perceived performance. Invariably, producers wrongly estimate pig weights or the decision is based on the pen of lightest pigs. |
| Feed budgeting, or preplanning the amount of each diet to be delivered in the sequence, can help avoid overfeeding the more expensive first diets and allows for performance monitoring. |
4. Use proper diet specifications and processing:
|
Another feed management mistake can be wrong feed specification and wrong diet sequencing. |
|
Big strides have recently been made in the calculation of requirements using lean growth estimates. |
| Fine grinding increases the grain particle size and allows for greater interaction with digestive enzymes. When particle size is reduced from 1200 to 600 micron the dray matter and nitrogen excretion are reduced by 20 and 24% respectively. |
| The South African industry-average maize particle size is approximately 1200 micron representing a 6 to 7% loss in feed digestibility. |
5. Set targets for feed cost per gain
Another common mistake is failure to set feed cost per unit of gain targets. The cost per unit of gain is a function of feed costs and feed efficiency.
6. Health management plan
| Two and three-site production systems and all-in, all-out (AIAO) flow have led to the assumption that health would be greatly improved. While health risks are reduced, they have not resulted in the reductions many expected. In fact, many producers approach health decisions on an as-needed basis, rather than develop a plan. |
| As a minimum, a health plan should include: · Whole herd vaccination plan for farrow-to-finish systems · Implementing training procedures to minimize health challenges as they occur. · Following the 10 steps listed in the Pork Quality Assurance Level III certification for responsible drug usage. |
7. Proper temperatures in the pig zone
|
Pigs are still exposed to too much temperature variation. |
| Hand operated curtains often result in too little ventilation. This often leads to cannibalism, increases health problems, slows feed intakes and growth rates. |
| Another local problem is the absence of cooling systems and/or mechanical ventilation during the summer months. |
8. Reduce times pigs are mixed
|
Sorting pigs by size when filling the house may be counterproductive to the goal of uniform performance. |
|
When sorting by size, producers should consider these questions: |
 | Will the smallest pigs be managed differently from the majority? |
| Will the smallest pigs be allowed to consume the higher density diets longer? |
| Will pen modifications allow for reduced competition or warmer temperatures or meet some other need? |
| Increasing data suggests that sorting pigs at arrival so pens are uniform in size does not improve performance. In fact, it’s been found that fighting increases as pigs of the same size establish social ranking. |
| With a large variation of weight from the start, there is less fighting as pigs recognize size as a determinant of social rank. |
9. Replace old feeders
| New feeder designs reduce wastage and may limit feed intakes. |
| Producers may object to removing what appear to be perfectly good feeders, so consider that an improvement in feed conversion of 0.1 units with feed costing R1150/t per ton, is worth R11.44 per pig. At 2.7 turns per year and eight pigs per feeder space (some new feeders can be stocked at 12 pigs per space), this is $30.88 (R247) per space per year. |
10. Consider contract finish
| For many producers, ownership of finishing facilities is not feasible due to other capital needs in farming or other constraints. |
| In addition, the number of pigs weaned at one time is insufficient to implement AIAO pig flows in competitively priced facilities. |
| For nursery and grow-finish, as the size of the facility increases, the cost per pig space decreases. While a common value given for constructing a fully slatted finisher with 1,000 pigs per room is $150-$170 per pig space, the cost jumps to over $200 per pig space with 300 pigs per room. Small producers should contract with neighbours to end up with a cost of production similar to larger units. |
Mike Brumm & Walter Scharlach
Phytaze in Broiler Breeder Diets
The efficacy of phytase in improving phytate phosphorus utilization in poultry feeds and reducing phosphorus in waste has been demonstrated in a large number of research trials involving commercial layers and broilers. Adoption of phytase use by the broiler, layer, and swine industries also serves as evidence of the efficacy of phytase. However, broiler breeders, in addition to the requirements for growth and maintenance, must produce fertile, hatchable eggs. Until now, there have been no studies of phytase use in breeder feeds. The purpose of this study was to determine whether broiler breeders would respond to microbial phytase in a manner similar to broilers and commercial layers.
Breeder hens were reared to 21 weeks of age in a commercial pullet house. The pullets were transferred to a slat/litter breeder house at the Poultry Research unit, Auburn University where they were randomly assigned to one of 16 pens—80 hens, and 8 males (cocks/roosters?) per pen. Pens, in groups of four, were assigned to one of two treatments. The control treatment contained a typical industry level of available phosphorus (0.30%).
The phytase treatment was formulated to contain 0.10% available phosphorus with phytase added to provide 300 PTU/kg feed. In both treatments, calcium levels were maintained at 2.75%. Roosters were fed a common feed for both treatments. The birds were fed according to primary breeder recommendations. Criteria used to measure response were liveability, body weight, egg production, eggshell quality, fertility, hatch and bone quality.
Over the duration of the experiment, phytase-fed birds averaged 54.44% production per hen per day as compared to 51.06% for the control group. Mortality was about 11% for the phytase-fed birds as compared to 21% for the controls. Over the life of the flock, the hens fed the control diet produced 125 hatching eggs per hen housed while the phytase-fed birds produced an average of 133 hatching eggs. The improvement in hatching egg production by the phytase-fed birds was about 8%.
Little difference in egg production was observed during the first 8 to 10 weeks of production. From 34 weeks of age, the phytase-fed birds began to exhibit greater egg production than the control group. By 45 weeks of age, the phytase-fed birds were laying about 6% more eggs than the control group. The weight of eggs produced by the phytase-fed birds and the control birds did not differ.
Based on eggshell weight and egg specific gravity, no differences in eggshell quantity or quality were evident between treatments. No differences in body weight between the two dietary treatments were observed until the hens were about 44 to 48 weeks of age. At this time, hens fed the control diet gained body weight at a more rapid rate than the phytase-fed hens. It would appear that phytase-fed birds were using energy for egg production rather than body weight gain.
Fertility and hatchability differed very little between the two treatments until the birds were about 44 weeks of age. After that, the phytase-fed birds maintained better fertility and hatch than the control-fed birds. Overall, there was an improvement of 1.2% in fertility and 2.4% in hatch with the phytase-fed hens. Average hatch of eggs from the control group was 82.76% as compared to 85.12% for the phytase-fed birds.
Over the 35 weeks of this experiment, hens fed the control diet produced an average of 103 chicks per hen while the phytase-fed group produced an average of 113 chicks.
A critical measure of phosphorus adequacy of the feed is bone strength. Leg bones from phytase-fed hens showed slightly greater resistance to breaking under pressure than bones from the control group. Mineral content of the bones was also slightly greater for bones from the phytase-fed group.
A summary of the results of using phytase to provide a portion of the available phosphorus needed in broiler breeder diets is provided in the table. Over the duration of the trial, the phytase-fed birds exhibited improved egg production of about 8%, improved fertility of 1.2%, improved hatch of 2.4% and improved livability of 10%.
Studies with poultry and with swine have demonstrated that the degradation of the phytate molecule by phytase releases nutrients other than phosphorus. In the design of this trial, release of these nutrients was not considered in diet formulation. Improved availability offers a possible explanation for the benefits associated with phytase use. The improvements attributed to use of phytase in this trial may be the result of release of energy, protein, amino acids, and/or minerals other than phosphorus.
The data from this trial demonstrate that microbial phytase can be used in broiler breeder feeds to replace a portion of inorganic phosphorus.
Response |
Control |
Phytase |
Mortality (%) |
21 |
11 |
Body Weight (kg) |
3.69 |
3.57 |
Egg Production (% hen/day) |
51.06 |
54.44 |
Egg Weight (g) |
61.19 |
61.24 |
Specific Gravity (g) |
1.08 |
1.08 |
Fertility (%) |
94.84 |
96.05 |
Hatchability (%) |
82.76 |
85.12 |
Bone Breaking Strength (kg) |
18.4 |
19.1 |
Wallace Berry
Poultry Science Department, Auburn University
Uniformity is a measure of the variability of bird size in a flock. Mostly this is measured by means of a co-efficient of variation (CV). Many flocks have high CV’s due to a number of easily identifiable factors.
Poor uniformity in young birds is compounded during growth, leading to problems at processing, particularly when customers have weight range requirements. Numerous factors affect flock uniformity, most of which are within hatchery and/or producer control.
Strain Differences:
There are differences in growth rates and proportions of different strains of broiler. It is therefore not a good idea to mix strains of bird.Sex Differences:
There is a 200-350 gram difference between males and females at 6 weeks of age. Growing sexes separately has its benefits as males get to market a week earlier. In addition, male aggression means dominance at the feeders and drinkers, leading to variable growth.Chick Weight:
Egg weights vary from flock to flock resulting in different size chicks. The adage "A poor start means a poor finish." is amplified with varying chick size. It is well documented that the smaller eggs from younger breeders hatch a few hours sooner than eggs from older breeder flocks.Hatching earlier leaves these small chicks in the hatcher where they dehydrate to a greater extent than later and larger hatchlings. This combined with the moisture loss that occurs during transport and holding, results in a 10-20 gram difference in weight at 3 days of age. This can have a snowball effect throughout the cycle.
There are some options to deal with smaller chicks:
| Place chicks from young breeder flocks separately. |
| Grade eggs from young breeders the first 8-12 weeks and set the larger eggs several hours earlier. |
| Deliver chicks from young flocks first. |
| Cull the flock heavily the first week. |
| Reduce room temperature more gradually. Start at 2-3°C above normal practice. |
Dehydration: The optimum time to place chicks is 8 to 12 hours post hatch. Chick
weight decreases linearly over time due to dehydration. Thus the longer it takes to place them the more dehydrated they become.The key to reducing dehydration is to ensure water availability as soon as possible. Chicks should be placed close to the drinkers. They will tend to congregate at the drinkers as they rehydrate, so having adequate drinkers is essential. The use of electrolytes and glucose in the water improves chick survival.
Dehydrated chicks do not respond to water availability uniformly. Dehydrated individuals are more lethargic and although they may find the water, will not drink. Mortality begins to increase at day 2-4 as yolk reserves are depleted.
Improper Holding and Brooding Temperatures:
Chicks lack the ability to control their body temperature until feathers have developed. Heat must therefore be provided, preferably in an even manner over the chick boxes. | Overheating chicks during transport accelerates dehydration. |
| Chicks chilled in transport show a lack of movement and seek warmth before drinking. They tend to huddle leading to a rise in mortality due to crowding and dehydration. |
| House temperature too low. Birds have a greater desire to be comfortable than to eat or drink and will huddle together. |
| Light intensity must be high enough for birds to find the feed and water during the first 48 hours. |
| Increased density causes extra competition at feeders and drinkers. Drafts, hot or cold areas will cause chicks to migrate to more comfortable areas thus increasing the bird density above desired levels. |
Individual chicks vary in their reaction to these conditions, which leads to greater variation.
Ventilation:
Birds have fresh air at all times. Ventilation rates need to be optimum for the stage of growth and house conditions. Air should never be directed onto the chick (even warm air), as the chicks are not comfortable in a draft.Activity:
The strain of broiler, lighting intensity, light programs, equipment placement and bird density impact on the activity level of a broiler flock. Active birds are lighter in weight as they burn off more energy and require more feed to meet their body’s requirement for maintenance.Equipment Adjustment: Smaller
chicks are often not able to reach the drinker and consume droppings in order to consume moisture, leaving them open to increased bacterial load in the gut. As birds grow, grow feeder height must be adjusted (the lip of the feeder pan should 2.5 cm above the birds back). This increases available floor space and flock movement is unhindered by feeder lines. Smaller birds will struggle more to feed as feeders are raised.Poor placement of feeder and drinker lines could mean that birds have to move too far to eat or drink. The distance moved and the increased contact with other birds means increased scratching in broiler flocks. This adds to the individual stress level of birds and in turn, size variation. Birds should not have to move more than 3m for food and/or water.
Feed Quality:
Unbalanced diets will affect the birds’ ability to meet their genetic potential. Poor quality feed ingredients will exacerbate this. Poor pellet quality slows consumption and birds that eat later are faced with consuming the fines left in feeders. Fines are usually higher in mineral and micro-ingredient content and lower in protein and energy.Behaviour in Accessing Feed:
Little or no competition for feed exists at placement but as the broiler grows this changes. Competition at the feeder will have lasting effects as the weaker birds will have to wait to eat. Anything that increases this competitive behaviour leads to increased variability.
| Controlled or restrictive feeding programs, increase competition. |
| If feeder lines do not empty at the same times birds will move around the house greatly increasing competition. |
| Smaller birds spend more time scratching through the litter for spilled feed, in turn adding to gut bacterial load. |
Disease:
Disease has a major impact on flock uniformity. Early exposure to disease elements usually has the worst and most lasting effect on the uniformity of a flock. Correct vaccination and medication are essential if this is to be prevented.
Agriculture and Marketing
Canada
While surfing the net recently I came across the site of the Australian Rural Industries Research and Development Corporation (http://www.rirdc.gov.au/). They describe their function as being "about managing and funding priority research and translating results into practical outcomes for industry development. Put simply, our business is about new products and services and new and better ways of producing them. "
Changes in the structure of the Australian egg industry and the importation of modern hybrids have meant that they have allocated a fair amount of funding to the egg industry. Complete reports on this research appear on the site. Many of these documents are 50 pages long so I felt that it would be a good idea to summarise some of their findings in this edition of the newsletter.
Pre-Layer Diets
A study was carried out to study the effect of feeding a pre-layer diet containing 2 g/kg of calcium from 15 to 18 weeks of age to determine this procedure’s effect on subsequent feed intake. An interaction was shown to exist between the diet fed prior to lay and the protein concentration of the layer diets on egg production.
Diet Fed Prior to Lay |
Protein content of layer diet (g/kg) |
|
160 |
180 |
|
|
Hen-day |
||
Grower |
90.5a |
88.2ab |
Pre-layer |
88.0b |
89.8ab |
|
Hen-housed |
||
Grower |
89.5a |
86.5ab |
Pre-layer |
85.3b |
89.4b |
Although the effects were not significant, hens fed the pre-layer diet had numerically lower immunoglobulin titres than birds fed grower diets.
Clearly, there were few benefits from feeding a pre-layer diet, indeed it may even have been detrimental when feeding a diet with a 16% protein content.
Amino Acid and Energy Requirements
Working with ISA Brown birds a number of experiments were carried out to determine the optimum energy level of the diets offered to laying birds. Three dietary ME levels were fed to hens housed in single-bird and two-bird cages. The calculated ME values of the diets were 10.6 (L), 11.4 (M) and 12.2 (H) MJ/kg. Amino acids, total protein, calcium and phosphorus were maintained in approximate proportion to the ME levels.
The results indicated that the Isa Brown bird is inefficient at adjusting feed intake to meet energy requirements. The ME intake on diet H appeared to be excessive while intake of ME and/or other nutrients on diet L may have been too low to support maximum egg mass output. Feed intake of diet L, which was a very bulky (low density) diet, was substantially lower than predicted on the basis of energy requirement of the birds and energy content of the diet, suggesting that dietary bulk was a limiting factor. Nevertheless profit was maximised with this diet under Queensland cost/price conditions.
Thus, it appears that diets with a low to medium energy content and proportionately lower protein content are likely to be more economical than higher density diets in most circumstances.
Diets used to examine the protein, lysine and methionine requirements during lay contained calculated ME concentrations of 11-11.25 MJ/kg. Diets containing 160 or 180 g crude protein/kg in one experiment, lysine concentrations ranging from 7.35 to 8.95 g/kg in a second experiment and methionine concentrations ranging from 2.83 to 3.83 g/kg in a third experiment were fed to hens in single- and 5-bird cages.
The production advantages of increasing the layer diet from 160 to 180 g/kg were limited to a small, significant increase in egg mass output due mainly to a significant increase in egg weight.
Interestingly, the lysine and methionine requirements for hens in single cages were lower than for hens in multiple 5-bird cages. The requirements of the latter hens are more applicable to the commercial situation and were shown to approximate 970 mg lysine/day and 430 mg methionine/day.
At the calculated dietary ME concentration of 11.25 MJ/kg used in these studies these intakes were attained with dietary concentrations of 7.75 g lysine/kg and 3.33 g methionine/kg. SPESFEED’s specification for a Layer 105 is 7.43 g lysine/kg and 3.3 g methionine/kg .
In a second series of experiments, the optimal amino acid allocation for laying hens was calculated using programs called "Winfeed" and "Aa-Opt", based on the well-known Reading model and supplied and developed by EFG Software, University of Natal.
Two strains of layer, differing in bodyweight and performance characteristics, were divided into three bodyweight categories at 18 weeks of age. Each of these six classes was fed a diet designed by Winfeed/Aa-Opt specifically for that class ("target" diets), and these were compared with diets having amino acid specifications 10% lower and 10% higher than the target diets. For each strain there was also a control treatment comprising uncategorised birds fed on a least-cost diet (LCD) formulated to commercial specifications.
The experimental diets were fed from 22 weeks of age and were reformulated at eight-week intervals.
After the first three periods (24 weeks) of the experiment the control diet was reformulated to a lower specification, and again after the fifth period (40 weeks). A summary of the results achieved by the heavy strain (Ingham SB2) appear in the table below:
Treatment |
Egg no (%) |
Egg wt (g) |
Feed cons (g/d) |
Marginc/bird.d |
|
Weight Category |
Formulate Basis |
||||
Low |
-10% |
81.92 |
59.80 |
116.9 |
4.177 |
Low |
Aa-Opt |
83.40 |
59.15 |
118.9 |
4.000 |
Low |
+10% |
82.97 |
60.01 |
118.8 |
3.875 |
Medium |
-10% |
85.43 |
60.85 |
122.2 |
4.490 |
Medium |
Aa-Opt |
84.63 |
60.74 |
123.2 |
4.193 |
Medium |
+10% |
85.27 |
60.20 |
123.6 |
3.958 |
High |
-10% |
84.03 |
62.48 |
131.6 |
4.343 |
High |
Aa-Opt |
85.55 |
62.84 |
132.5 |
4.379 |
High |
+10% |
86.59 |
62.44 |
132.2 |
4.136 |
|
Control |
Least cost |
85.03 |
60.98 |
120.1 |
4.532 |
|
LSD |
NS |
1.23 |
2.8 |
||
As can be seen gross margins were higher for the control groups fed LCD-formulated diets.
It was concluded that:
| The results show that improved methods of predicting layer performance need to be found before such models can be successfully applied in practice. |
| The relationships between intakes of specific amino acids and egg output have not been sufficiently well worked out to provide an effective economic model. |
| In terms of the degree of sophistication the technology appears to have outstripped the information required to use it effectively. |
| The apparent failure of the diet formulation program to create diets appropriate for the different classes of bird throughout the laying period, makes it impossible to consider the benefits of using different diets for different categories (strain and bodyweight) of layer. |
If these results are repeatable, this trial has some serious academic and possible commercial implications. My own MSc was based on the theory of the Reading Model and now I find that it may not work!
Rick Kleyn
Photoperiod Control of Dairy Cows
I am always on the lookout for small things that can make a big difference to the cost effectiveness of an operation. A recent article in Feedstuffs discussed a means of improving the cost effectiveness of dairying.
Photoperiod (day length) can be effectively used to improve production efficiency in lactating cows.
Long days are considered to be continuous exposure to 16 to 18 hours of light.
Through the work of numerous trials it has been shown that long daylengths will increase milk production by 2.27 kg per day, but it will incur the cost of additional feed intake (0.81 kg) per day as well as an additional energy cost and capital costs. The table below is based on an exchange rate of R 8.00 to the US $.
Table: Milk price sensitivity to photoperiod management for a typical 250-cow herd
Milk Price (R/l) |
2.46 |
2.11 |
1.58 |
Increased Milk (l) |
2.27 |
2.27 |
2.27 |
Milk Income (R) |
5.58 |
4.78 |
3.58 |
Additional Feed (R) |
0.88 |
0.88 |
0.88 |
Electricity (R) |
0.32 |
0.32 |
0.32 |
Total Cost (R) |
1.20 |
1.20 |
1.20 |
Net Profit (R) |
4.38 |
3.58 |
2.38 |
Annual Profit (R) |
330000 |
270000 |
180000 |
The take-home message is that extending the photoperiod of lactating cows is simple to implement, easy to manage and profitable.
Geoffrey Dahl
Feedstuffs, June 11, 2001
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