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1. An experiment was conducted to determine the effect of the source of fat (soybean oil or tallow) on the ileal endogenous amino acid (EAA) losses in broilers. 2. Three nitrogen (N)-free diets; a control diet with no added fat and test diets with 60 g/kg of either soybean oil or tallow were formulated. Titanium dioxide (5 g/kg) was added to all diets as an indigestible marker. Each diet was assigned to six replicate cages (eight birds per cage) from d 18 to 21 post-hatch. On d 21, the digesta were collected from the lower half of the ileum. 3. The endogenous losses of nitrogen and amino acids (AA) were lower (p = 0.08; p = 0.001) in broilers fed diets with soybean oil or tallow, respectively, compared to those fed the diet with no fat. Source of fat had no influence (p > 0.05) on EAA losses. 4. The most abundant AA in the ileal endogenous protein was glutamic acid, followed by aspartic acid, threonine, leucine, serine, valine and proline. In general, the concentrations of AA in the endogenous protein were lower (p < 0.05) with added fat. The exceptions were methionine, cysteine, proline and serine, which were unaffected. The effect of fat source on the AA contents of endogenous protein were inconsistent and differed depending on the AA. 5. The inclusion of fats decreased EAA losses which implied they have beneficial effects beyond direct energy contribution. It can be proposed that the reduction of EAA flow may be an additional mechanism contributing to the extra-caloric effect of dietary fats. [ABSTRACT FROM AUTHOR]

Two experiments evaluated different fat sources and levels on growth performance, carcass characteristics, and economic impact in commercial finishing pigs. In experiment 1, 2,160 pigs (337 × 1,050, PIC; initially 37.3 ± 0.93 kg) were used. Pens of pigs were blocked by initial body weight and randomly assigned to one of four dietary treatments. Three of the four dietary treatments included: 0%, 1%, and 3% choice white grease. The final treatment contained no added fat until pigs were approximately 100 kg, and then a diet containing 3% fat was fed until marketing. Experimental diets were fed over four phases and were corn–soybean meal based with 40% distillers dried grains with solubles. Overall, increasing choice white grease decreased (linear, P = 0.006) average daily feed intake (ADFI) and increased (linear, P = 0.006) G:F. Pigs fed 3% fat only during the late-finishing phase (~100 to 129 kg) had similar G:F compared to pigs fed 3% for the entire study during the late-finishing phase, and intermediate G:F overall. Increasing fat tended to increase (linear, P = 0.068) hot carcass weight (HCW). Feed cost increased (linear, P ≤ 0.005) and income over feed cost decreased (linear, P ≤ 0.041) as choice white grease increased. In Experiment 2, 2,011 pigs (PIC 1,050 × DNA 600; initially 28.3 ± 0.53 kg) were used. Pens of pigs were blocked by location in the barn and randomly assigned to one of five dietary treatments arranged in a 2 × 2 + 1 factorial with main effects of fat source (choice white grease or corn oil) and level (1% or 3% of the diet) and a control diet with no added fat. Overall, increasing fat, regardless of source, increased (linear, P < 0.001) average daily gain (ADG), decreased (linear, P = 0.013) ADFI, and increased (linear, P < 0.001) G:F. Increasing fat increased (linear, P ≤ 0.016) HCW, carcass yield, and backfat depth. There was a fat source × level interaction (P < 0.001) in carcass fat iodine value (IV), where IV increased to a greater extent in pigs fed corn oil with only a small increase in IV in pigs fed diets with choice white grease. In conclusion, these experiments suggest that increasing fat from 0% to 3%, regardless of source, produced variable responses in ADG but consistently improved G:F. Increasing fat increased HCW, carcass yield, and backfat depth, but feeding diets containing corn oil increased carcass IV. With the ingredient prices used, the improvement in growth performance did not justify the extra diet cost from increasing fat from 0% to 3% in most situations. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of embryonic thermal manipulation and dietary fat source during the finisher period on carcass characteristics and breast muscle myopathies following acute heat stress. Thermal manipulation (TM) of incubation temperatures has been shown to improve bird resistance to heat stress and enhance breast muscle growth. Fat supplementation is frequently used during heat stress and fat source may alter carcass composition, as fat sources rich in unsaturated fatty acids have been shown to reduce fat pad weight. Ross 708 eggs were incubated at 37.5°C except during TM when temperature was increased to 39.5°C for 12 h daily from embryo day 7 to 16. A total of 1,080 chicks were reared under standard conditions until acute heat stress at 43 d. Dietary treatments were applied during the finisher period beginning at 28 d, with diets including 4.5% of soya oil, poultry fat, or olive oil. At 49 d, 240 male birds were processed to assess carcass and portion weights, as well as breast quality. Carcass and portion weights were decreased by TM, however percent yield was similar to the controls. A decrease in breast muscle myopathies was noted but may have been due to the lower BW of the TM birds. Interactions between the treatments suggest that TM may alter lipid metabolism. Differences in dietary fat source did not affect carcass characteristics. The reduction in breast muscle myopathies may be negated by the negative impact of TM on carcass weights. [ABSTRACT FROM AUTHOR]

Modern broilers have been selected for rapid growth but demonstrate reduced heat tolerance toward market age. As the poultry industry expands globally, strategies must be developed to support broiler performance in challenging climates. The objective of this study was to evaluate the effect of embryonic thermal manipulation (TM) and dietary fat source during the finisher period on broiler performance during acute heat stress (AHS) close to market age. The cyclic exposure to high temperatures during mid-incubation used in TM has been demonstrated to improve broiler tolerance to heat stress. However, high incubation temperatures can be detrimental to embryonic development and impair posthatch broiler performance. Embryos were exposed to 39.5°C for 12 h daily from incubation day 7 to 16 to assess the impact of TM on hatching and broiler performance. Dietary fat is commonly added to poultry diets during heat stress and it was theorized that differences in fat source may further impact bird performance. Finisher diets were supplemented with soya oil, poultry fat, or olive oil at 4.5% each. Broilers were exposed to a period of AHS at 43 d. Embryo mortality was increased, and hatchability was reduced by TM. Broiler performance was also decreased for the TM birds, but mortality during AHS was markedly reduced. Dietary fat source did not influence bird performance but was shown to interact with incubation treatment. Overall, the present data suggest optimal performance in modern broiler strains may be at odds with improved heat tolerance. [ABSTRACT FROM AUTHOR]

Two experiments evaluated different fat sources and levels on growth performance and carcass characteristics in commercial finishing pigs. In Exp. 1, pigs (n = 2,160 337 × 1050, PIC; initial BW 37.3 ± 0.93 kg) were used. Pens of pigs were blocked by initial BW and randomly assigned to 1 of 4 dietary treatments. Three of the treatments included: 0, 1, and 3% choice white grease fed throughout the trial. The final treatment contained no added fat until pigs were approximately 100 kg, and then the diet containing 3% fat was fed. Experimental diets were fed over 4 phases and were corn-soybean meal-based with 40% dried distillers grains with solubles. There were 27 pigs per pen and 20 replications per treatment. Overall, increasing choice white grease decreased (linear, P = 0.006) ADFI and increased (linear, P = 0.006) G:F without influencing ADG (Table 1). Pigs fed 3% fat only during the late finishing phase (approximately 100 to 129 kg) had similar G:F compared with pigs fed 3% fat for the entire study. Increasing fat tended to increase (linear, P = 0.068) HCW. In Exp. 2, pigs (n = 2,011 PIC 1050 × DNA 600; initially 28.3 ± 0.53 kg) were used. Pens of pigs were blocked by location in the barn and randomly assigned to 1 of 5 dietary treatments arranged in a 2 × 2 + 1 factorial with main effects of fat source (choice white grease or corn oil) and level (1 or 3% of the diet) and a control diet with no added fat. There were 16 replications per treatment with 21 to 27 pigs per pen. Overall, increasing fat, regardless of source, increased (linear, P < 0.001) ADG, decreased (linear, P = 0.013) ADFI, and increased (linear, P < 0.001) G:F. Increasing fat increased (linear, P ≤ 0.016) HCW, carcass yield, and backfat depth (Table 2). There was a fat source × level interaction (P < 0.001) in belly fat iodine value (IV), where IV increased to a greater extent in pigs fed diets containing corn oil with only a small increase in IV in pigs fed diets with choice white grease. In conclusion, the results from these experiments suggest that increasing fat from 0 to 3%, regardless of source, produced variable responses in ADG but consistently improved G:F. Increasing fat increased HCW, carcass yield, and backfat depth, but feeding diets containing corn oil increased belly fat IV to a greater magnitude than choice white grease. [ABSTRACT FROM AUTHOR]

• The effects of alfalfa hay to corn silage (AH: CS) ratio (70:30 vs. 30:70) in high-concentrate diets containing two sources of fat supplements (calcium salts of palm fatty acids vs. C16:0 enriched palm fat) on production responses and milk fat secretion of dairy cows were evaluated. • The source of fat supplement interacted with AH: CS ratio to affect milk fatty acid profile and protein yield but not milk production of dairy cows. The effects of alfalfa hay to corn silage (AH:CS) ratio in high-concentrate diets containing 2 sources of fat supplements on production responses and milk fat secretion of dairy cows were evaluated using 8 lactating multiparous Holstein cows in a duplicated Latin square with a 2 × 2 factorial arrangement of diets with 21-d experimental periods. Diets comprised AH:CS ratios of 70:30 or 30:70 supplemented with either calcium salts of palm fatty acids (FA; CaS-FA, 3.5% of dietary dry matter (DM)) or C16:0 enriched palm fat (Palm-FA; 3.0 % of dietary DM). Dry matter intake (DMI) was greater (1.74 kg/d) in cows fed high compared with low AH:CS ratio. Similarly, the high AH:CS ratio had greater production of milk yield, 3.5% fat-corrected milk, and energy-corrected milk compared with low AH:CS ratio whereas fat sources did not differ in any of these parameters with the exception of greater milk yield by CaS-FA compared with Palm-FA. Milk protein yield was the greatest in the high AH:CS ratio + CaS-FA diet. Milk protein content was greater for diets containing the high AH:CS ratio and also for Palm-FA vs. CaS-FA diets. Milk fat yield was not affected by the treatments, but milk fat content was greater for Palm-FA diets. Feed efficiency (milk yield/DMI) was the lowest for the high AH:CS ratio + Palm-FA diet. The molar proportion of propionate was greater for diets containing high AH: CS ratio, but otherwise volatile FA were not affected by treatments. The high AH:CS ratio had greater de novo synthesized FA (< C16:0) in milk fat without affecting mixed-origin FA (C16:0 plus cis -9 C16:1) or preformed FA (> C16) compared with Palm-FA. CaS-FA had greater proportions and yields of de novo synthesized and mixed-origin FA, and lower preformed FA including many C18 biohydrogenation intermediates such as trans -10 C18:1 and trans -10, cis -12 C18:2 which are due to greater intake of n -6 C18:2 indicating altered ruminal biohydrogenation. CaS-FA also had greater unsaturated FA in milk fat compared with Palm-FA. Overall, the source of fat supplement interacted with AH:CS ratio affecting milk FA profile and protein yield but not milk production of dairy cows. [ABSTRACT FROM AUTHOR]

Objective: This experiment aimed to investigate the effect of different sources and inclusion levels of dietary fat on productive performance and egg quality in laying hens raised under hot environmental conditions. Methods: A total of 480 Hy-Line Brown laying hens at 31 wk of age were randomly allotted to 1 of 5 experimental diets. The control diet contained 2,800 kcal/kg nitrogen-corrected apparent metabolizable energy with no fat addition. Four additional diets were prepared by adding 2.0% or 4.0% of animal fat (AF) or soybean oil (SO). Energy and nutrient concentrations were consistent among all diets. Diets were fed to hens for 4 weeks. Average daily room temperature and humidity were 26.7°C±1.52°C and 77.4%±4.50%. The heat stress index was approximately 76, indicating that hens were raised under heat stress conditions. Results: Final body weight (BW) was greater (p<0.05) for hens fed diets containing 2.0% or 4.0% AF than for those fed the control diet or diets containing 2.0% or 4.0% SO. The BW gain and feed intake were greater (p<0.05) for hens fed diets containing additional AF or SO than those fed the control diet. Eggshell thickness was the greatest (p<0.05) for hens fed the control diet, but the least (p<0.05) for hens fed diets containing 4.0% SO. Egg yolk color was the greatest (p<0.05) for hens fed the control diet, but the least (p<0.05) for hens fed diets containing 4.0% SO. Conclusion: Inclusion of supplemental fat (AF and SO) in diets exhibits preventative effects on BW loss for hens raised under hot environmental conditions when energy and nutrient concentrations in diets were maintained. The effects were greater for AF than for SO. However, inclusion of supplemental fat in diets decreases eggshell thickness and egg yolk yellowness, possibly due to a reduction in Ca absorption and intake of egg yolk colorants. [ABSTRACT FROM AUTHOR]

Simple Summary: Understanding fat sensing in chickens has the potential to improve least cost feed formulation relevant to poultry feeds. Acid oils (soybean acid oil and palm fatty acid distillate) are economical and sustainable feedstuffs with similar fatty acid composition to crude oils (soybean oil and palm oil) but richer in free fatty acids. However, potential issues relevant to the palatability of these oils have been raised. Four experimental diets were offered in a series of double-choice tests to study the effect of free fatty acid content and the unsaturated:saturated ratio on dietary preferences in hens. Hens showed a feed preference for palm oil added diets over soybean oil diets, with palm oil and palm fatty acid distillate being equally preferred. However, the hens demonstrated a preference for soybean oil when offered in choice with soybean acid oil. In conclusion, free fatty acid content and saturation degree affected feed preferences in hens. The use of oils with greater preference values may give rise to greater feed palatability, enhancing feed intake at critical stages. Behavioural and genetic evidence shows that the taste system is intimately related to the sensing of nutrients with consequences for poultry nutrition practices. A better understanding of how chickens may sense fat could provide the background for selecting feedstuffs used in poultry feeds. Acid oils have the potential to be economical and sustainable feedstuffs. These fat by-products from the edible oil refining industry possess a similar fatty acid composition to the crude oils but are richer in free fatty acids (FFA). An experiment was conducted to study the effect of FFA content and the unsaturated:saturated ratio (U:S) on dietary preferences in hens. Four fat sources were added to a basal diet at an inclusion rate of 6%, determining the experimental diets: soybean oil (SO; high U:S, 5% FFA); soybean acid oil (SA; high U:S, 50% FFA); palm oil (PO; low U:S, 5% FFA); and palm fatty acid distillate (PFAD; low U:S, 50% FFA). The experimental diets were offered in a series of double-choice tests to forty-eight Lohmann Brown laying hens housed individually in cages. Each hen was offered the ten potential binary combinations of the four diets including each diet compared to itself (referred to as four control double-choices). Feed intake was measured for two hours twice a day after one hour of fasting. Consumption was analysed as a standard preference index (% of test diet intake in comparison with the total intake). Preference values were compared to the random choice value of 50% using the Student's t-test. None of the four control comparisons differ significantly from 50% (p > 0.05), indicating that the changes in preference values observed in the other binary comparisons were related to the dietary changes associated to fat ingredients. Hens showed a feed preference for palm oil added diets over soybean oil diets (p < 0.05), with PO and PFAD being equally preferred (p < 0.05). However, in this trial the hens demonstrated a preference for SO (low %FFA) when offered in choice with SA (high %FFA) (p < 0.05). These results suggest that the degree of saturation plays an important role in dietary fat preferences: hens prefer predominantly saturated oils even when these are rich in FFA. Furthermore, when presented with a choice between predominantly unsaturated oils, hens prefer feed with a low %FFA. In conclusion, %FFA and the U:S ratio affected feed preferences in hens. The use of oils with greater preference values may give rise to greater feed palatability, enhancing feed intake at critical stages. [ABSTRACT FROM AUTHOR]