α‐Tocopherol absorption and polyunsaturated fatty acid metabolism in the developing chick embryo

1. A study has been made relating α‐tocopherol uptake from the yolk and yolk sac membrane to the polyunsaturated fatty acid status of the liver during incubation.

2. Whereas at day 15 of incubation lipid in the liver showed an exceedingly high degree of unsaturation and potential for oxidation because of accumulation of C20 and C22 polyunsaturated fatty acids, α‐tocopherol concentrations were exceedingly low.

3. In contrast, very high concentrations of α‐tocopherol occurred within the liver just before hatching by which time amounts of polyunsaturates and the need for oxidation protection had reduced considerably.     

Alteration of fatty acid profile and nucleotide-related substances in post-mortem breast meat of α-lipoic acid-fed broiler chickens

1. The present study was conducted to determine the effects of α-lipoic acid supplementation on post-mortem changes in the fatty acid profile and concentrations of nucleotide-related substances, especially those of a taste-active compound, inosine 5?-monophosphate, in chicken meat.

2. Mixed-sex broiler chicks aged 14 d were divided into three groups of 16 birds each and were fed on diets supplemented with α-lipoic acid at levels of 0, 100 or 200 mg/kg for 4 weeks. Blood and breast muscle samples were taken at 42 d of age under the fed condition and then after fasting for 18 h. The breast muscle obtained from fasted chickens was subsequently refrigerated at 2°C for one and 3 d.

3. α-Lipoic acid supplementation did not affect any plasma metabolite concentration independently of feeding condition, while a slight increase in plasma glucose concentration was shown with both administration levels of α-lipoic acid. In early post-mortem breast muscle under the fed condition, α-lipoic acid had no effect on concentrations of fatty acids or nucleotides of ATP, ADP, and AMP.

4. In post-mortem breast tissues obtained from fasted chickens, total fatty acid concentrations were markedly increased by α-lipoic acid feeding at 200 mg/kg irrespective of length of refrigeration. This effect was dependent on stearic acid, oleic acid, linoleic acid and linolenic acid. However, among fatty acids, the only predominantly increased unsaturated fatty acid was oleic acid.

5. Dietary supplementation with α-lipoic acid at 200 mg/kg increased the inosine 5?-monophosphate concentration in breast meat and, in contrast, reduced the subsequent catabolites, inosine and xanthine, regardless of the length of refrigeration.

6. Therefore, the present study suggests that α-lipoic acid administration altered the fatty acid profile and improved meat quality by increasing taste-active substances in the post-mortem meat obtained from fasted chickens.

     

Is it possible to increase n-3 fatty acid content of meat without affecting its technological and/or sensory quality and the growing performance of chickens?

1. The aim of this study was to increase the content of n-3 fatty acids (FA) of meat without affecting its sensory and/or technological properties or the growth performance of chickens reared under standard conditions. Male chickens, Ross 308, were distributed into 5 groups corresponding to 5 different diets for the growing and finishing periods: control (T), containing extruded linseeds exhibiting high concentration of fibre (ELHF), extruded linseeds exhibiting low concentration of fibre (ELLF), microalgae, or an association of 75% ELLF and 25% MA (ELLF+MA).

2. The diet containing microalgae induced a decrease in feed consumption without affecting growth rate. Chickens exhibited a lower feed conversion ratio than the other groups for the growing and finishing periods but also the whole rearing period. The use of linseeds in diets had no effect on the growth performance of chickens in comparison to the control group.

3. The dietary enrichment with n-3 FA had few effects on carcass composition or the ultimate pH and colour of breast meat. The microalgae increased the meat susceptibility to oxidation. The lipid content of breast meat was not affected by the diets. The breast meat of chickens fed on diets containing linseeds and/or microalgae had greater n-3 FA content (2.4 to 3.9 times higher than group T). The linseeds and microalgae mainly increased the contents in linolenic acid and long chain n-3 FA, respectively.

4. Dietary enrichment with n-3 FA had no effect on the sensory quality of fillets whereas the thighs of the MA group exhibited the lowest score for the flavour “chicken” and the greatest score for the flavour “abnormal” corresponding to a fish flavour.

     

Effects of dietary concentrate level and chromium-methionine supplementation on ruminal fermentation,and ruminal bacterial and fatty acid composition in Tan lambs北大核心CSCD

This study evaluated the effects of dietary concentrate level and chromium methionine(Cr-Met)supplementation on ruminal fermentation and fatty acid composition, and ruminal bacteria abundance in Tan lambs. Forty male Tan lambs [(21.00±1.23) kg body weight, 5 months of age] were randomly assigned to four treatment groups with 10 lambs in each treatment. The treatments were: a low-concentrate (LC) diet (concentrate:forage, 35:65) without Cr-Met supplementation; a high-concentrate (HC) diet (concentrate:forage, 55:45) without Cr-Met supplementation; groups fed the HC diet with 0.75 or 1.50 g·d-1·lamb-1 Cr-Met (HCM and HCH, respectively). Ruminal fluid was collected on day 65 with an oral stomach tube about 3 h after the morning feed and samples used for fermentation analysis, fatty acid composition determination and bacterial DNA extraction. It was found that: 1) Ruminal pH, acetate proportion and acetate:propionate were greater (P<0.05) with the LC diet whereas microbial crude protein, propionate and valerate proportions were greater (P<0.05) with the HC diet. The acetate:propionate was greater (P<0.05) in the HCM group than in the HC group. 2) For the HC diet, the DNA abundances of Butyrivibrio fibrisolvens vaccenic acid subgroup (Butyrivibrio VA) and Ruminococcus flavefaciens were decreased (P<0.05), compared with the LC diet, whereas the DNA abundance of Anaerovibrio lipolytica was increased (P<0.05). For lambs fed the HC diet, DNA abundances of B. fibrisolvens stearic acid subgroup, Butyrivibrio VA, Butyrivibrio proteoclasticus, and A. lipolytica showed a linear decrease (P<0.05) with increasing Cr-Met supplementation level; However, the DNA abundance of R. flavefaciens showed a linear increase (P<0.05). 3) Compared with the LC group, the concentrations of t11 C18:1, trans C18:1, c9t11 CLA, t10c12 CLA, C18:2n6, and C18:3n3 were decreased by the HC diet without Cr-Met supplementation whereas the concentration of C18:0 was increased. There was a linear increase in t11 C18:1 and trans C18:1 with increasing Cr-Met supplementation level in lambs fed the HC diet. The results suggest that the HC diet inhibited the growth of ruminal bacteria involved in the ruminal biohydrogenation process, and the addition of Cr-Met had a potentially positive effect on conjugated linoleic acid (CLA) synthesis in body tissue. © 2022, Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

Is it possible to increase the n-3 fatty acid content of eggs without affecting their technological and/or sensorial quality and the laying performance of hens?

1. The aim of this study was to increase the n-3 fatty acid (n-3 FA) content of eggs without affecting their sensorial and/or technological properties or the laying performance of hens. Laying hens from line 477 were divided into 5 groups corresponding to 5 different diets over the laying period: control diet (C) and diets containing extruded linseed with a high level of fibre (ELHF), extruded linseed with a low level of fibre (ELLF), microalgae, or a combination of 75% ELLF and 25% MA (ELLF+MA).

2. Dietary enrichment with n-3 FA had no effect on the laying performance, hen body weight or egg white viscosity. The egg yolks produced by hens fed the diet containing microalgae were redder than egg yolks from the other groups, suggesting the presence of red pigments in the microalgae preparation. However, the colour difference was low and not perceptible to the human eye. Moreover, colour measurement of egg yolks by sensorial analysis panellists using the Roche colour fan did not reveal a diet effect on this parameter.

3. Egg yolk lipid content was not affected by diet. The egg yolk of hens fed on diets containing linseed and/or microalgae had greater n-3 FA content (×2.5 to 2.9 compared to group C). Linseed mainly increased the linolenic acid content (×3.0 to 3.4 compared to group C) and the microalgae increased the LC n-3 FA content (×4.1 compared to group C). Dietary enrichment with n-3 FA had no effect on the sensorial quality of shell cooked eggs except for the “unusual flavour” criterion for which the score was higher for the MA group compared to the other groups and corresponded to a fishy flavour.

     

Evaluation of fatty acid metabolism and innate immunity interactions between commercial broiler,F1 layer × broiler cross and commercial layer strains selected for different growth potentials

Background: The broiler industry has undergone intense genetic selection over the past 50 yr. resulting in improvements for growth and feed efficiency, however, significant variation remains for performance and growth traits. Production improvements have been coupled with unfavourable metabolic consequences, including immunological trade-offs for growth, and excess fat deposition. To determine whether interactions between fatty acid(FA) metabolism and innate immunity may be associated with performance variations commonly seen within commercial broiler flocks, total carcass lipid %, carcass and blood FA composition, as wel as genes involved with FA metabolism, immunity and cel ular stress were investigated in male birds of a broiler strain, layer strain and F1 layer × broiler cross at d 14 post hatch. Heterophil:lymphocyte ratios, relative organ weights and bodyweight data were also compared.Results: Broiler bodyweight(n = 12) was four times that of layers(n = 12) by d 14 and had significantly higher carcass fat percentage compared to the cross(n = 6; P = 0.002) and layers(P = 0.017) which were not significantly different from each other(P = 0.523). The carcass and whole blood FA analysis revealed differences in the FA composition between the three groups indicating altered FA metabolism, despite al being raised on the same diet. Genes associated with FA synthesis andβ-oxidation were upregulated in the broilers compared to the layers indicating a net overal increase in FA metabolism,which may be driven by the larger relative liver size as a percentage of bodyweight in the broilers. Genes involved in innate immunity such as TLR2 and TLR4, as wel as organel e stress indicators ERN1 and XBP1 were found to be nonsignificant, with the exception of high expression levels of XBP1 in layers compared to the cross and broilers. Additional y there was no difference in heterophil: lymphocytes between any of the birds.Conclusions: The results provide evidence that genetic selection may be associated with altered metabolic processes between broilers, layers and their F1 cross. Whilst there is no evidence of interactions between FA metabolism, innate immunity or cel ular stress, further investigations at later time points as growth and fat deposition increase would provide useful information as to the effects of divergent selection on key metabolic and immunological processes.     

Lactobacillus frumenti mediates energy production via fatty acid β-oxidation in the liver of early-weaned piglets

Background: Early-weaning of piglets is often accompanied by severe disorders, especially diarrhea. The gut microbiota and its metabolites play a critical role in the maintenance of the physiologic and metabolic homeostasis of the host. Our previous studies have demonstrated that oral administration of Lactobacillus frumenti improves epithelial barrier functions and confers diarrhea resistance in early-weaned piglets. However,the metabolic response to L. frumenti administration remains unclear. Then, we conducted simultaneous serum and hepatic metabolomic analyses in early-weaned piglets administered by L. frumenti or phosphatebuffered saline(PBS).Results: A total of 100 6-day-old crossbred piglets(Landrace × Yorkshire) were randomly divided into two groups and piglets received PBS(sterile, 2 m L) or L. frumenti(suspension in PBS, 10~8 CFU/m L, 2 m L) by oral administration once per day from 6 to 20 days of age. Piglets were weaned at 21 days of age. Serum and liver samples for metabolomic analyses were collected at 26 days of age. Principal components analysis(PCA)showed that L. frumenti altered metabolism in serum and liver. Numerous correlations(P 0.05) were identified among the serum and liver metabolites that were affected by L. frumenti. Concentrations of guanosine monophosphate(GMP), inosine monophosphate(IMP), and uric acid were higher in serum of L.frumenti administration piglets. Pathway analysis indicated that L. frumenti regulated fatty acid and amino acid metabolism in serum and liver. Concentrations of fatty acid β-oxidation related metabolites in serum(such as3-hydroxybutyrylcarnitine, C4-OH) and liver(such as acetylcarnitine) were increased after L. frumenti administration.Conclusions: Our findings suggest that L. frumenti regulates lipid metabolism and amino acid metabolism in the liver of early-weaned piglets, where it promotes fatty acid β-oxidation and energy production. High serum concentrations of nucleotide intermediates, which may be an alternative strategy to reduce the incidence of diarrhea in early-weaned piglets, were further detected. These findings broaden our understanding of the relationships between the gut microbiota and nutrient metabolism in the early-weaned piglets.     

Effects of ascorbic acid and α-lipoic acid on performance and meat quality of broilers subjected to heat stress

1. The present study was aimed to investigate the effect of adding ascorbic acid or α-lipoic acid to to the diet of broilers exposed to heat stress on performance and meat quality.

2. Heat stress caused a decrease in final body weight and feed consumption, whilst ascorbic acid (AA) and α-lipoic acid (ALA) partly prevented the decrease in final body weight of males.

3. While heat stress increased the pH values of broiler drumsticks and breast meat, AA and ALA partly reduced this increase. For meat quality, AA and ALA reduced the adverse effects on the relative yellowness value, particularly on d 14 of storage.

4. It was determined that heat stress affected the microbiological quality of meat adversely, and that AA and ALA alleviated this effect to a certain extent.

5. In conclusion, while heat stress affected body weight gain and meat quality adversely, the supplementation of the ration with AA and ALA partly alleviated these adverse effects.     

Can breeder reproductive status,performance and egg quality be enhanced by supplementation and transition of n‐3 fatty acids?

The aim of this experiment was to investigate the effect of n‐3 fatty acid (FA) supplemented diets on breeder performance, productivity and egg quality. Breeders (n = 480) were fed the supplemented diet from 18 weeks onwards; the inclusion level of n‐3 FA was increased from 1.5% to 3.0% from 34 weeks of age onwards until 48 weeks of age. Ross‐308 broiler breeders (n = 480) were fed one of four different diets: a basal diet rich in n‐6 FA (control diet) or one of three diets rich in n‐3 FA. For the n‐3 FA diets, eicosapentaenoic acid (EPA, 20:5 n‐3) and docosahexaenoic acid (DHA, 22:6 n‐3) were fed to the broiler breeders at different ratios formulated to obtain EPA/DHA ratios of 1/1, 1/2 or 2/1. Differences in performance, reproduction and egg quality parameters due to n‐3 supplementation were noted more for the 1.5% followed by the 3.0% fed broilers than their 1.5% supplemented counterparts. Egg weight (p < 0.001) and egg mass (p = 0.003) were significantly lower and feed conversion (p = 0.008) significantly higher for the n‐3 FA (at 3.0% inclusion level) fed broilers compared to the control group. For the EPA‐ and DHA‐fed breeders, a higher proportional abdominal fat percentage (p = 0.025) and proportional albumen weight (%) (p = 0.041) were found respectively. Dietary treatments did not affect reproduction. It can be concluded that the results of the present experiment indicate no significant differences between treatments at 1.5% inclusion levels. However, increasing this level to 3.0% is not recommended due to the rather negative effects on the measured parameters. It should be further investigated whether these adverse effects were obtained due to (i) the higher supplementation level, (ii) combining a supplementation level of 1.5% with 3% or (iii) the duration of supplementation.     

Alleviative effects of α-lipoic acid supplementation on acute heat stress-induced thermal panting and the level of plasma nonesterified fatty acids in hypothyroid broiler chickens

1. The present study was conducted to examine the effects of α-lipoic acid on hypothyroidism-induced negative growth performance and whether α-lipoic acid alleviates acute heat stress in relation to hypothyroid status.

2. Female broiler chickens (14?d-old) were fed diets supplemented with α-lipoic acid (100?mg/kg) and an antithyroid substance, propylthiouracil (200?mg/kg), for 20?d under thermoneutral conditions (25°C). At 42?d of age, chickens were exposed to a high ambient temperature (36°C, 60% RH) for 4?h.

3. Under the thermoneutral condition, propylthiouracil administration decreased feed efficiency and concomitantly increased adipose tissue and thyroid gland weights. Plasma nonesterified fatty acids and triacylglycerol were also increased by propylthiouracil administration. However, α-lipoic acid supplementation did not affect the hypothyroidism-induced effects.

4. In hypothyroid chickens, the rise in respiratory rate induced by heat exposure was greatly inhibited by α-lipoic acid administration at 1?h, but this effect had disappeared at 4?h. In addition, a similar inhibitory effect on the concentrations of plasma nonesterified fatty acids was subsequently observed at 4?h.

5. Therefore, the present study suggested that α-lipoic acid alleviates acute heat stress if chickens are in a hypothyroid status.     

Studies on acid oils and fatty acids for chickens. III. Effect of chemical composition on metabolisable energy of by‐products of vegetable oil refining

1. Fourteen by‐products of oil refining, selected for their variability in free fatty acid and unsaponifiable contents, were analysed chemically with the objective of relating the determined ME values of the products to chemical composition by means of multiple linear regression analysis. Refined sunflower oil was included as a reference fat.

2. Twenty‐one 2‐week‐old chicks were used to determine fat digestibilities and AMEn values of diets, using the total collection method. Fats were included in a wheat‐soyabean meal diet at 100 g/kg. Multiple linear regression analysis was used to express the ME values of fats as functions of the parameters measured (moisture, gross energy, impurities, unsaponifiables, non eluted material, free fatty acid content, unsaturated: saturated ratio, peroxide value, TBA test).

3. The ME of the fat products lay in the range 12.62 to 24.35 MJ/kg, and 29.26 MJ/kg for refined sunflower oil. Free fatty acid content of the fats was shown to be a poor predictor of their ME values, whereas non eluted material (NEM) of the fat products showed a good correlation with their ME. A regression equation could be derived (R² = 0.6548; SEE = 2–0064) with the unsaturated: saturated ratio (U:S) and NEM. An ME prediction equation based on the U:S, NEM and unsaponifiable content is also proposed (R² = 0–7168; SEE= 1.9058).     

Effects of dietary enrichment with n–3 fatty acids on the quality of raw and processed breast meat of high and low growth rate chickens

1. The enrichment of raw poultry meat with n–3 fatty acids (n–3 FA) has been investigated in detail, particularly in high growth rate genotype standard broiler chickens, whereas low growth rate genotype Label Rouge chickens have received less attention. With the increased development of processed poultry products, it is necessary to ensure that the nutritional and sensory quality of meat enriched with n–3 FA is not affected by processing.

2. Two experiments were undertaken for this purpose. In the first experiment, 696 male Ross 708 chickens were reared under standard conditions, and in the second, 750 male JA 657 chickens were reared under Label Rouge conditions. All birds received the same starting and growing diets containing palm and soya oils in each experiment. Birds were distributed into three groups from 21 or 57 d of age for standard and Label Rouge chickens, respectively, and given a control, linseed oil or extruded linseed diet. Diets were also supplemented with vitamin E (100–200 mg/kg). Birds were slaughtered at 56 or 84 d of age for standard and Label Rouge chickens, respectively. A total amount of 60 kg of breast meat from each group was processed into white cured-cooked meat.

3. The dietary treatment had no effect on the growth performance of chickens or meat yield. The use of extruded linseed or linseed oil only decreased the carcass fatness of the standard chickens but had no effect on the carcass fatness of Label Rouge chickens. The nutritional quality of raw and cured-cooked meat was improved (increased concentration of n–3 FA), whereas the technological quality of the meat (pH, juice loss after cold storage, susceptibility to oxidation, colour, processing yield and shear force value) and sensory quality of the processed products were not or slightly affected.

4. Linked to lower breast yield, to lower lipid content in breast meat and to higher slaughter age, Label Rouge chickens seemed to be less efficient for n–3 FA deposition in breast muscles than standard chickens.     

Production,chemical composition,and fatty acid profile of milk from buffaloes fed with cupuaçu (Theobroma grandiflorum) cake and murumuru (Astrocaryum murumuru) cake in the Eastern Amazon

The objective was to evaluate the effect of concentrate supplementation using by-products of the Amazonian industry on milk production, milk composition, and milk fatty acid profile of dairy buffaloes. Twelve lactating buffaloes (544.5 ± 35.6 kg, 6.4 ± 2.2 years old, 59 ± 6 days in milk) were allotted in a pasture of Mombaça grass and managed under rotational grazing (4 days occupancy/28 days rest). A 3 × 3 Latin square was adopted, and each animal alternately received three supplementary treatments based on corn bran + soybean meal or cupuaçu cake or murumuru cake for 21 days per treatment. Murumuru cake increased the levels of lauric acid and myristic acid in the milk (p < 0.05). Murumuru cake reduced the unsaturated fatty acid contents in the milk compared with animals fed control diet or cupuaçu cake (24.27% vs. 25.24% vs. 25.08%). The n-6/n-3 ratio was 2.6, 1.97, and 2.0 in the control, cupuaçu, and murumuru groups, respectively. Based on this parameter, cakes made from cupuaçu as well as murumuru could be considered to be adequate for inclusion in dairy water buffalo feed. However, the murumuru cake addition requires some caution because its use induces the secretion of higher levels of lauric and myristic fatty acids that are related to human cardiovascular disease.     

Effect of different roughages sources on performance,milk composition,fatty acid profile,and milk cholesterol content of feedlot feed crossbred cows (Holstein × Zebu)

Tropical Animal Health and Production - The aim of the study was to evaluate the effect of different forage sources in diets for feedlot dairy cows and their implications on production,...     

Molecular weight and amino acid composition of fowl delta‐globulin

1. The molecular weight of delta‐globulin was estimated chromato‐graphically to be about 10,700 daltons.

2. Ultracentrifuge experiments at 2.7 × 10⁵ g gave values of s _{20, W} = (1.49 + 0.16C) × 10^?13 s for the sedimentation coefficient and D_{20 w} = (1.12 + 0.19c) × 10^?6 cm² s^?1 for the diffusion coefficient, c being the protein concentration (g/100 ml).

3. According to the Svedberg equation, these imply a molecular weight of 12,470 daltons, assuming [v_bar] = 0.74 ml/g.

4. Using refractometer measurements of protein concentration it was found that E ^1% _1cm (278 nm) = 5.57 at pH 7.8.

5. From the ultraviolet absorption spectrum of the protein in 0.1 N NaOH it was concluded that the molecule probably contains four tyrosine residues and no tryptophan.

6. On this basis a revised amino acid composition is given.     

The effect of 5-aminoimidazole-4-carboxamide ribonucleoside （AICAR） on fatty acid oxidation in hepatocytes isolated from neonatal p~glets

In the present study, the effect of 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) on long-chain fatty acid oxidation by hepatocytes isolated from suckled neonatal pig liver (a low ketogenic and lipogenic tissue) was tested. Incubation of hepatocytes with AICAR (0.5 mM) in the presence of 1 mM of carnitine and 10 mM of glucose for 1 hour at 37°C had no significant effect on total [1-14C]-palmitate (0.5 mM) oxidation (14CO2 and 14C-Acid soluble products (ASP)). Consistent with the fatty acid oxidation, carnitine palmitoyltransferase I activity and inhibition of its activity by malonyl-CoA (10 μM) assayed in cell homogenate also remained constant. However, addition of AICAR to the hepatocytes decreased 14CO2 production by 18% compared to control (p < 0.06). The reduction of labeled carboxylic carbon accumulated in CO2 caused a significant difference in distribution of oxidative products between 14CO2 and 14C-ASP (p < 0.03) compared with the control. It was also noticed that acetyl-CoA carboxylase (ACC) was increased by AICAR (p < 0.03), indicating that ACC might drive acetyl-CoA toward fatty acid synthesis pathway and induce an increase in distribution of fatty acid carbon to 14C-ASP. Addition of insulin to hepatocyte incubations with AICAR did not change the oxidative product distribution between CO2 and ASP, but further promoted ACC activity. The increased ACC activity was 70% higher than in the control group when citrate was absent in the reaction medium and was 30% higher when citrate was present in the medium. Our results suggest that AICAR may affect the distribution of metabolic products from fatty acid oxidation by changing ACC activity in hepatocyte isolated from suckled neonatal piglets; however, the basis for the increase in ACC activity elicited by AICAR is not apparent.     

Impact of different inclusion levels of oil palm (Elaeis guineensis Jacq.) fronds on fatty acid profiles of goat muscles

The effects of different inclusion levels of oil palm fronds (OPF) on the fatty acid profile of the longissimus dorsi (LD), biceps femoris (BF) and infraspinatus (IS) muscle of goats fed for 100 days are described. Twenty‐four individually housed Kacang crossbred male goats (averaged 21.7 ± 0.97 kg BW) were allocated to three groups receiving either a 100% concentrate control diet (CON), diet with 25% inclusion level of OPF (HAF) or a diet with 50% inclusion of OPF. The diets were adjusted to be isocaloric and isonitrogenous and fed at 3.0% of BW daily. Samples of LD, BF and IS muscles were taken at slaughter for the determination of fatty acid profiles. The total saturated fatty acids (SFA) in the LD and BF muscles of the OPF group were significantly (p < 0.05) lower than the CON group. For all muscles, C18:3n‐3 and total n‐3 polyunsaturated fatty acid (PUFA) were significantly higher (p < 0.05) in the OPF group than the CON group with minimal impact on the C18:2n‐6 and total n‐6PUFA. Consequently, the n‐6:n‐3 ratio significantly (p < 0.05) decreased in the OPF group compared to the CON group. The LD muscle had a significantly higher conjugated linoleic acid 18:2 c19t11 compared to other muscles. There were no interactions between muscle x diet except for total SFA. It is concluded that OPF at 25–50% inclusion levels may decrease the SFA and increase the n‐3PUFA content in chevon, with no apparent adverse effects on the growth performance of the animals, can be used as a feed ingredient to support goat farming in countries that lack grazing pasture.     

Comparative responses of genetically lean and fat chickens to lysine,arginine and non‐essential amino acid supply. II. plasma amino acid responses

1. Three experiments performed to study the effects of amino acid imbalances on the growth of genetically lean (LL) and fat (FL) male chickens from 28 to 42 d of age were described by Leclercq et al. (1994). The plasma amino acid concentrations of birds on selected treatments from that paper are reported here. In experiment 1, three dietary concentrations of digestible lysine were compared (4.75, 6.75 and 7.75 g/kg). In experiment 2, two dietary concentrations of digestible arginine were compared (6.53 and 10.00 g/kg). In experiment 3, three diets were compared: a high‐protein diet (189 g CP/kg), a low‐protein diet containing added essential amino acids (144 g CP/kg), and this low‐protein diet supplemented with 40 g/kg of non‐essential amino acids (NEAA; glutamic and aspartic acids).

2. The present results are compared with two earlier reports on the same genotypes. The LL consistently had lower plasma concentrations of me‐thionine, cystine, phenlyalanine, isoleucine and valine, and higher concentrations of histidine, than the FL chickens. In 4 of 5 experiments, LL leucine concentrations were lower, and glutamic acid, tyrosine, glutamine and alanine were higher, than in the FL. The other amino acids measured; arginine, lysine, aspartic acid, glycine and serine, exhibited variable responses among the experiments.

3. When the limiting essential amino acids, lysine and arginine, were added to a deficient diet, the plasma concentration of the supplemented amino acid increased while the others remained constant or decreased.

4. When glutamic and aspartic acids were added to the low protein diet, plasma amino acid responses were similar to those of adding a limiting amino acid to a deficient diet, except that alanine exhibited a dramatic increase.

5. Although there were genotype by diet interactions for several amino acids, the interactions were caused by differences in the degree of the responses, not in their direction.

6. These results suggest that the FL and LL genotypes do not utilise various amino acids with the same efficiency and, as a consequence, the ideal profile of dietary amino acids should not be the same for both lines. The results support the hypothesis that selection for fatness and leanness changed the amino acid requirements independently of the: effects of food intake.     

Comparison between pre‐ and postnatal acid‐base status of calves and their perinatal mortality

Summary

The acid‐base status of 58 calves (all in normal anterior presentation) was determined from venous blood samples before the onset of traction and immediately after vaginal delivery.

Calves were assigned to one of three groups according to their blood pH value: group 1 ‐ normal, pH >7.2; group 2 ‐ acidotic, pH 7.2 to 7.0; group 3 ‐ severely acidotic, pH < 7.0. Before the onset of traction (i.e. during the 30 minutes following the appearance and rupture of the membranes), 43 calves (74.1%) had normal acid‐base values, 14 (24.1%) had slight acidosis, and only 1 (1.7%) had severe acidosis. At birth the three groups of calves showed the following distribution: 23 (39.7%) were normal, 29 (50%) had slight acidosis, and 6 (10.3%) had severe acidosis.

Seven calves (12. 1%) died during birth or within 48 hours after birth; 2 were normal shortly before birth, 4 were acidotic shortly before birth, and 1 was severely acidotic even before the onset of traction. Traction was significantly longer for cows that delivered severely acidotic calves compared to cows in the other two groups.     

Maximum nutritional response to poor‐quality protein and amino acid utilisation

1. Although the theory of responses to amino acids suggests that, providing sufficient of the limiting amino acid is fed, it should be possible to elicit maximum growth response, maximum response is not usually elicited by poor‐quality proteins.

2. It has been suggested that this failure to elicit maximum response is a reflection of poorer limiting amino acid utilisation from poor‐quality proteins. This interpretation conflicts with the theory of general amino acid imbalance which proposes that amino acid excesses do not impair the utilisation of the limiting amino acid.

3. Three protein mixtures of different quality were made by mixing maize gluten meal and soyabean protein concentrate in constant proportions, supplementing with tryptophan, threonine and arginine to adequacy and varying amino acid score (0'62, 0^‐71 or = 1–0) by varying additions of free lysine. The 3 mixtures were diluted with protein‐free ingredients to produce 3 diet series, each providing 3–7, 6–5, 9–2, 120, 14–8 and 17–5 g lysine per kg. Each diet was fed to 4 cages of 2 chickens each from 4 to 14 d of age in a randomised block experiment. Food intake, body‐weight and body‐nitrogen gain were measured.

4. Differences in protein quality were confirmed by regression analyses of body‐weight response to protein intake (Net Protein Ratio) and body‐nitrogen response to nitrogen intake (Net Protein Utilisation) in the linear range. Regression analyses in the linear range of body‐weight or body‐nitrogen response to lysine intake showed no adverse effect of protein quality on lysine utilisation. Curvilnear analysis (Reading flock response model) confirmed this finding.

5. Maximum response could not be obtained with the poorest protein quality. It is illogical to invoke impaired utilisation of the limiting amino acid to explain this. A small decrease in net energy yield of the diet may be sufficient to explain the effect, but it is more likely that the depletion of the limiting amino acid from tissue (muscle) protein which results from feeding poor‐quality protein explains the effect.