Modulation of conjugated linoleic acid-induced loss of chicken egg hatchability by dietary soybean oil.

The main objective of the present study was to determine the minimum level of dietary plant oil supplementation that results in full recovery from loss of hatchability induced by conjugated linoleic acid (CLA). Another objective was to define the changes in egg yolk fatty acid composition associated with the loss and recovery of hatchability. Shaver hens were assigned to groups of 8 and were fed a diet containing either no CLA plus 0.5% soybean oil (control) or 0.5% CLA (1:1 mixture of cis-9, trans-11 and trans-10, cis-12 CLA) plus 0, 2, 4, 6, or 8% soybean oil for 15 d. Supplementation with CLA (CLA plus 0% soybean oil) resulted in complete loss of hatchability of fertile eggs. Hatchability was progressively improved by increasing doses of soybean oil, and full recovery of hatchability compared with the control levels was achieved at 6% soybean oil. There was no further improvement in hatchability when 8% soybean oil was added to the CLA-supplemented diet. Loss of hatchability was associated with a 2- to 3-fold decrease in desaturase ratios (cis-9 C16:1/C16:0 and cis-9 C18:1/C18:0) in the egg yolk total lipids, indicating marked inhibition of delta-9 desaturase in the chicken liver. In addition, the concentration of arachidonic acid was observed to decrease. Recovery of hatchability was associated with an increased proportion of linoleic acid and linolenic acid in the egg yolk. However, there was no change in desaturase ratios, suggesting that delta-9 desaturase inhibition persisted. Increased incorporation of dietary linoleic and linolenic acids might have compensated for the reduced levels of palmitoleic and oleic acid, thus allowing for the improvement in hatchability.

Rapeseed and soybean products as protein sources for growing turkeys of different ages.

(1) Apparent ileal and total tract protein digestibilities of rapeseed meal and cake and soybean meal and cake were assayed in growing turkeys at 4, 8 and 12 weeks of age. (2) In addition, the effect of killing technique on apparent ileal protein digestibility values obtained by a slaughter method and effect of rapeseed feeding on size of specific organs were studied. (3) Protein digestibility coefficients of rapeseed products were mostly 0.10 to 0.15 units lower than those of soybean products. Ileal digestibility of protein increased slightly or remained unchanged from 4 to 8 weeks and decreased thereafter. No effect of feed processing method (meal vs cake) on ileal digestibility was observed. (4) Killing the birds by carbon dioxide inhalation and bleeding led to slightly lower ileal digestibility values than mechanical stunning and neck dislocation. (5) Total tract digestibility of protein decreased from 4 to 8 weeks of age for soybean meal and rapeseed meal but increased for soybean cake and rapeseed cake. From 8 to 12 weeks of age total tract digestibility of protein decreased for all the products tested. (6) Feed containing rapeseed led to enlargement of thyroid glands and hearts, but did not affect liver size or mortality.

Effects of preservation method and beta-glucanase supplementation on ileal amino acid digestibility and feeding value of barley for poultry.

1. Effects of preservation method (drying or air-tight storage of whole grain and ensiling of rolled high-moisture grain) and beta-glucanase supplementation (Econase) on apparent ileal amino acid digestibilities and metabolisable energy content of barley were evaluated with Ross broiler chickens. In addition, the effect of barley preservation method was assessed using Leghorn cockerels. 2. Birds were given either a semi-purified soyabean meal basal diet or a mixture of the basal diet and barley (50:50 on dry matter basis). Apparent ileal digestibilities (AID) of nutrients were assessed using the slaughter technique. AID of nutrients and nutrient digestibility measured using excreta (AED) were determined using chromium mordanted straw as an indigestible marker. 3. In broilers, AID of amino acids, dry matter and organic matter were lower for dried than air-tight stored barley, particularly for diets based on ensiled barley. In cockerels, barley preservation method had no effect on amino acid AID. The AED of nutrients and nitrogen corrected apparent metabolisable energy content (AMEn) was highest for ensiled barley across both experiments. 4. beta-glucanase supplementation increased nutrient digestibility, phosphorus retention and AMEn content of air-tight stored and dried barley diets in particular but had only negligible effects on ensiled barley. Beta-glucanase improved the AID of amino acids in dried barley but not in air-tight stored or ensiled barley. 5. Amino acid digestibilities were lower in broilers than cockerels and the effect of barley preservation on feeding value of barley was different for broilers and cockerels.