The objective of this trial was to compare the effects of OH-Methionine compared to DL-Methionine on laying performance and egg quality of Babcock laying hens on a 14-week period under tropical climate. The work was presented in a poster at 22nd ESPN (European Symposium in Poultry Nutrition) in Gdansk (Poland) and in an oral communication by Dolores Batonon-Alavo at PSA (Poultry Science Association) in Montréal (Canada).
The study was performed on 448 Babcock layers reared from 17 to 31 weeks in collective cages at Sri Ramadhoota Poultry Research Farm Pvt Ltd, Hyderabad, India. Birds were randomly allocated to 2 treatments with 14 replicates of 16 hens each. Diets were based on corn, soybean meal and limestone formulated according to Rhodimet nutrition guide recommendations (Adisseo). The amino acid calculations were based on usual performance of laying hens observed in the experimental facility for daily feed intake and egg mass (taken as factors for amino acids optimization). Treatments consisted of two diets at requirement in Total Sulfur Amino Acids (TSAA), supplemented either with DL-Methionine (DL-Met, 99%) or OH-Methionine (OH-Met, 88%) at respective incorporation rates of 0.14% and 0.16% (Weight basis), assuming 100% bio-efficacy. In week 17, laying hens received experimental diets for a habituation period of two weeks. Then, the experiment ran from week 19 until week 31. During the whole experimental period, laying hens had free access to feed and water.
During the experiment, animals were exposed to tropical climate with high temperatures and air relative humidity levels. The mean temperature varied from 33.23 ± 3.6 °C and 26.45 ± 2.8 °C respectively for maximum and minimum for the habituation and first experimental period (week 18 to week 25). Then from week 26 to week 31, temperature range decreased to maximum 28.9 ± 3.2 °C and minimum 24.4 ± 1.8 °C. Regarding air relative humidity, from week 18 to week 31, this parameter increased slowly with averages values for morning and night of: 55%-40%; 60%-50%; 70-65% for each identified rearing period.
Layer’s body weights were recorded at week 17, week 23 and week 28. Egg weight, egg mass and egg production were measured at weekly intervals. Egg quality parameters: egg density, egg strength, Haugh units, shell weight, shell thickness, shell percent were recorded at week 22, week 26 and week 30, taking one egg per replicate for each treatment (N=14). Feed intakes of layers were assessed each day and Feed Conversion Ratio was calculated weekly. All the data were analyzed considering the three periods described before.
Each collective cage, containing 16 laying hens was considered as an experimental unit. Laying performance data were analyzed independently on the three periods corresponding to habituation period (18-20 weeks) first phase (21-25 weeks) and second phase (26-30 weeks). These three phases were chosen according to the start of laying, the first period corresponding to high ambient temperature and the second one corresponding to lower temperature. Egg quality parameters were analyzed using a two ways Anova analysis with Age and Treatment as main factors including the interaction between them (Age x Treat.). Differences between means were considered statistically different for P < 0.05 according to Student test.
No difference on laying performance or egg quality parameters between layers fed OH-Met or DL-Met.
No significant difference of body weight between dietary treatments was observed, indicating that DL-Met and OH-Met similarly sustain hens growth performance.
Feed intakes of laying hens are also similar for the two treatments throughout the trial (Graph 1)
These values are below the references of Babcock, which are defined for layers reared under temperate conditions. The tropical conditions seem to have impacted animals’ feed intake and hence laying performances.
However, the Feed Conversion Ratio of layers in the experiment are in line with Babcock references for the period from 23 to 31 weeks (Graph 2). The difference between our results and Babcock reference during the period 20-25 weeks, can be mainly explained by the low feed intake during this period and the start of lay, that decreased mechanically the FCR.
Egg weights are similar on the experimental period for layers fed with DL-Met or OH-Met (Graph 3).
Egg quality parameters were affected by the laying hens age but not by dietary treatments (Table 1).
In a nutshell, there is no significant difference of layers’ body weights between treatments indicating that DL-Methionine and OH-Methionine are similar in sustaining hens growth performance.
Based on the data, it was observed that there was no significant difference between DL-Methionine and OH-Methionine on egg production and egg quality variables in layers fed 100% TSAA and the inclusion levels methionine sources was as referred in the methodology.