For the next few months, our newsletter will spotlight scientific articles from researchers at the University of Alberta.
This month, we’re proud to showcase:
“Effects of Metabolizable Energy Intake and Body-Weight Restriction on Layer Pullets: 1-Growth, Uniformity, and Efficiency.”
Authored by U of A graduate students Thiago Noetzold and Jo Ann Chew, alongside renowned researchers Douglas Korver and Martin Zuidhof, this study offers valuable insights into poultry science, specifically focusing on optimizing growth, uniformity, and efficiency in layer pullets.
Read the summary below:
ABOUT
Egg-type chickens are highly efficient in egg production due to advances in genetic selection. Several countries worldwide keep laying hens in production until they are up to 100 wks of age. Management and nutrition of modern laying-hens need to be constantly examined to meet this genetic potential and determine where improvements can be made. In contrast with broiler breeders, feed restriction is not commonly implemented in commercial laying settings since these birds can autoregulate their feed intake. However, feed restriction programs might be helpful for optimal profit yield instead of optimal reproductive performance. The objective of this study was to determine the effect of dietary metabolizable energy levels and restricted or non-restricted feeding trajectories (meal every visit in the PF experiment and ad libitum in the CON experiment) on BW, BW uniformity, ADFI, MEI, FCR, and feed motivation of laying pullets reared to 18 wks of age. It was hypothesized that pullets fed on every visit in the precision feeding experiment and ad libitum in the conventional experiment would have greater BW, ADFI, and MEI than restricted-fed pullets. Uniformity would decrease with restricted feeding in the CON experiment due to competition but increase with restricted feeding in the PF experiment due to an imposed upper BW limit. Additionally, FCR would decrease as birds consumed diets containing greater dietary ME; however, MEI would be similar across the different ME diets.
APPROACH
Two simultaneous experiments were conducted using a PF system (Experiment 1) and a conventional feeding system (Experiment 2). The feeding stations were equipped with four independent feeders, enabling provision of treatment-specific diets to individual free-run birds.
Experiment 1. The PF experiment consisted of two feed allocation levels: meal every visit (MEV) or restricted; and four dietary apparent ME treatments (Low (2600Kcal/Kg), Standard (2800Kcal/Kg), High (3000Kcal/Kg), and Choice). There were 23 birds per treatment combination, totaling one hundred and eighty-four Lohmann Brown-Lite one-day-old pullets at the time of placement. Pullets were trained to use the feeding stations during their first five weeks of life. On day 42, individual precision feeding started, and birds were re-randomized among two large floor pens (4.5 × 5.4 m) with two four-feeder PF stations in each pen (approximately 45 birds per feeding station). The feeding stage was equipped with four feeders, and each feeder had a door, where the appropriate door opened for the dietary ME level of the given pullet that was allowed in the feeding stage. In the Choice feeding treatment, all four feeder doors were opened. All birds which qualified for a meal had access to the feed for 120 s. Data were collected using the PF system. BW and feed intake (FI) were recorded at every station visit. BW uniformity was indirectly calculated using the coefficient of variation (CV), expressed as percentage of BW standard deviation divided by the average BW, and the result multiplied by 100.
Experiment 2. It consisted of two levels of feed allocation (ad libitum or restricted) and three dietary apparent ME levels (Low, Std, and High). Theere were 312 Lohmann Brown-Lite one-day-old pullets in the CON experiment. Pullets were placed in 12 small pens (1.75 × 1.8 m) with 26 birds per pen. Each pen had 1 pan feeder. Ad libitum-fed birds had free access to feed. Birds from the restricted group received feed daily, with allowances based on weekly pen average BW to achieve the lower boundary of the Lohmann BW target trajectory. Bird BW was recorded manually on a weekly basis. Weekly FI was recorded at the pen level. Two percent of acid insoluble ash marker was mixed into the pre-lay diet and provided for 5 consecutive days. At 126 d, eight birds per treatment were randomly euthanized for ileal content collection. Digesta samples were collected to measure the gross energy (GEGE) of feed and digesta samples using bomb calorimetry.
ANALYSIS OF RESULTS
Overall, BW was similar across the treatment combinations in the PF experiment from 0 to 11 wks of age. The interaction between the FA and age showed increased BW in MEV-fed pullets as they aged compared to restricted-fed pullets. In the PF experiment, the overall CV was lower in the restricted group over time compared to the MEV-fed pullets. The average CV over the rearing period was lower in the High ME compared to the Std ME-fed pullets. The interaction between the FA and age showed a more pronounced decrease in CV as birds aged for restricted-fed compared to the MEV-fed pullets. In the CON experiment, the interaction between the FA and dietary ME showed lower average CV in the rearing for restricted High ME-fed pullets compared to the Low and Std ME groups, while that difference was not observed in the ad libitum-fed groups. In the PF experiment, ADFI was greater in pullets fed a Low ME diet compared to Std, High and Choice treatments, whereas in the CON experiment the lower the dietary ME, the greater the ADFI (Low ME > Std ME > High ME). In the PF and CON experiments, as pullets aged, ADFI increased in MEV- and ad libitum-fed pullets compared to the restricted birds, as well as in birds fed Low ME energy levels compared to the other energy levels. Average daily MEI increased in pullets fed the High ME diets compared to the Low ME and Choice feeding groups in the PF experiment, while in the CON experiment, the greater MEI was observed in birds fed the Std ME compared to the Low and High ME levels. Additionally, the interaction between feed allocation and dietary ME in the CON experiment showed that restricted-fed pullets had similar MEI between Std and High ME diets, but this difference was not observed when birds were fed ad libitum. In the PF experiment, pullets preferred feed with greater ME content, where the High ME diet had the greatest intake preference and the Low ME diet had the lowest. This feed consumption reflected a similar ME intake pattern to the different ME diets in the Choice group. In the PF experiment, FA levels did not affect cumulative FCR. However, birds fed the Low ME diet had greater FCR compared to the Std ME, High ME, and Choice feeding groups.
APPLICATION
The current trial was the first utilizing a precision feeding system equipped with multiple feeders, having the capacity for feeding specific diets to individual free-run birds. The results of the current study indicate that birds fed MEV and ad libitum increased BW, ADFI and MEI compared to birds whose BW was restricted to the lower boundary of the Lohmann-Brown-Lite recommended BW trajectory. The greatest BW uniformity was observed in the restricted precision-fed pullets. Pullets fed lower dietary ME levels increased ADFI and FCR and were not able to maintain similar MEI. Additionally, when given a choice, pullets preferred to consume diets containing greater ME levels. Based on efficiency, feeding birds with greater dietary ME and feed restriction is recommended, whereas for maximum growth (BW) and uniformity the feed restriction is not recommended. Despite the current results, better recommendations should be provided for after the laying cycle.
Read the full article at: https://doi.org/10.3390/poultry2040036
Thania joined PIP as the PIP Extension technician in 2021.
