Carcass and meat quality of light lambs using principal component analysis

Eighty-six male light lambs of Manchego breed were used in this study. Principal component (PC) analysis was performed to study the relationship between carcass quality variables (n=22) and between meat quality measures (n=21). The carcass quality was assessed using objective and subjective measurements of conformation and fatness besides the joints proportion and tissues proportion of the leg. The measurements used to evaluate meat quality were pH in longissimus dorsi and semitendinosus muscles, the colour, moisture, water holding capacity, cooking losses, texture and sensorial analysis on longissimus dorsi. The five first PCs explained about 77% of the total variability for carcass measures whereas for meat quality the 74% of the total variability was explained for the eight first PCs. All the carcass measurements showed similar weight to define the first PC, whereas the muscle and bone proportion as well as muscle:bone ratio of the leg were useful to define the second PC. The meat quality measures that were more effective to define the first PC were the meat colour measurements, whereas the sensorial variables defined the second PC. The projection of the carcass quality data in the first two PCs allowed to distinguish clearly between heavier carcasses (higher than 6.5 kg) and lighter carcasses (lower than 5.5 kg). The carcasses with a weight higher than 6.5 kg were on the left side of the figure, where the variables of conformation and fatness lie. The group of medium carcass weight were placed between the two previous groups. The projection of the meat quality data in the first two PCs did not differ between hot carcass weights, although there was a trend, the lighter carcasses lay on the left side of the graph, which implies small differences between meat quality in this range of carcass weight.     

The effect of fat-enriched diets on the perirenal fat quality and sensory characteristics of meat from rabbits

Two hundred and eighty four medium sized young rabbits were fed ad libitum with two fat-enriched experimental diets (V: vegetable fat, A: animal fat) and a control diet (C). Diet had a significant effect on the ultimate pH (pHu) of the Longissimus dorsi muscle and on the colour, weight and fatty acid composition of the perirenal fat. The carcasses from diet C had significantly less perirenal fat (14.2 g) compared to the carcasses from group A and V (24.4 and 23.0 g) using carcass weight and age of the animals as covariables. Supplementing the diet with animal fat produced perirenal fat which was richer in oleic acid (41%) than in groups V (20.9%) and C (27.9%). The P:S ratio was higher in group V (2.45) compared with groups A and C (0.53 and 0.42). Diet also affected the organoleptic quality of the loin meat. The meat from groups V and C was considered to have a more aniseed flavour than that from group A. In contrast the loin meat from group A had more liver flavour. Both groups V and A were considered juicier than group C. No differences were found in hardness, chewiness and fibrousness. These results suggest than from a human health point of view, the use of a diet supplemented with animal fat is useful on the basis of the nutritional index, P:S of the perirenal fat. However the amount of fat added in the diets V and A should be less than used in this study if the carcass is sold whole in order to avoid excessive perirenal fat. From an organoleptic point of view, the greater aniseed and grass flavour of group V compared to group A may give meat of better sensory quality.     

Supplementation with Cashew Nut and Cottonseed Meal to Modify Fatty Acid Content in Lamb Meat

This study evaluates the effect of cashew nut meal (CNM), whole cottonseed (WCS), and calcium salts of long‐chain fatty acids (Ca‐LCFA) on the fatty acid profiles of meat from hair lambs. Thirty‐five 60‐d‐old, male, noncastrated Santa Ines lambs with an initial average body weight of 13.00 ± 1.80 kg were used in a randomized complete‐block design with 7 blocks and 5 treatments. The experimental treatments consisted of a control diet (CON) without supplemental lipids and 4 test diets with different lipid supplements that were selected according to the degree of protection from ruminal hydrogenation and their polyunsaturated fatty acid richness. The tests diets included the following modifications: supplementation with WCS, supplementation with CNM, supplementation with both cottonseed and CNM (CSCNM), and supplementation with Ca‐LCFA. The C18:1n9c content was highest in the meat of the animals fed the CNM diet (42.00%). The meat from lambs fed the WCS and Ca‐LCFA diets had higher C18:0 contents (25.23 and 22.80%, respectively). The C16:1 content was higher in the meat from the animals fed the CNM and CON diets (1.54 and 1.49%, respectively). C18:2c9t11 concentration was higher in the meat from the animals fed the Ca‐LCFA and CNM diets. The estimated enzyme activity of Δ9‐desaturase C18 was highest in the muscles of the lambs fed the CON, CNM, and CSCNM diets. The use of cashew nuts in the diet resulted in an increase in the C18:2c9t11 content of the lamb meat, which improved the nutritional characteristics of the fat.     

The effect of olive leaves supplementation on the feed digestibility, growth performances of pigs and quality of pork meat

The influence of olive leaves supplementation on feed digestibility, growth performance of pigs and pork meat quality was investigated. Pigs fed diets with olive leaves at 5% (OL5) and 10% (OL10) levels had lower daily weight gain (DG) and daily feed intake (DFI) than pigs fed a conventional diet (OL0) but differences were not observed between groups fed with the different quantities of leaves. Additionally, pigs fed diets with leaves had the worst feed:gain ratio and showed a decrease in overall backfat. Chops from pigs fed the leaf diets had lower peroxide (PV) and conjugated diene (CD) contents than chops from pigs fed conventional diets. Moreover, chops from pigs fed with the higher quantity of leaves also showed a lower drip loss. After a storage period of 8 days at 4 °C, meat obtained from both OL5 and OL10 animals also differed (P < 0.05) in PV and %CD values from those fed a conventional diet. Since the fatty acid composition of the longissimus muscles was not different, differences in oxidative stability could only be explained by the significantly higher α-tocopherol concentration in intramuscular fat and backfat in pigs fed with olive leaf diets.     

Ruminal biohydrogenation and abomasal flow of fatty acids in lactating cows fed diets supplemented with soybean oil,whole soybeans,or calcium salts of fatty acids

Ruminants have a unique metabolism and digestion of unsaturated fatty acids (UFA). Unlike monogastric animals, the fatty acid (FA) profile ingested by ruminants is not the same as that reaching the small intestine. The objective of this study was to evaluate whole raw soybeans (WS) in diets as a replacer for calcium salts of fatty acids (CSFA) in terms of UFA profile in the abomasal digesta of early- to mid-lactation cows. Eight Holstein cows (80 ± 20 d in milk, 22.9 ± 0.69 kg/d of milk yield, and 580 ± 20 kg of body weight; mean ± standard deviation) with ruminal and abomasal cannulas were used in a 4 × 4 Latin square experiment with 22-d periods. The experiment evaluated different fat sources rich in linoleic acid on ruminal kinetics, ruminal fermentation, FA abomasal flow, and milk FA profile of cows assigned to treatment sequences containing a control (CON), with no fat source; soybean oil, added at 2.68% of diet dry matter (DM); WS, addition of WS at 14.3% of diet DM; and CSFA, addition of CSFA at 2.68% of diet DM. Dietary fat supplementation had no effect on nutrient intake and digestibility, with the exception of ether extract. Cows fed fat sources tended to have lower milk fat concentration than those fed CON. In general, diets containing fat sources tended to decrease ruminal neutral detergent fiber digestibility in relation to CON. Cows fed WS had lower ruminal digestibility of DM and higher abomasal flow of DM in comparison to cows fed CSFA. As expected, diets containing fat supplements increased FA abomasal flow of C18:0 and total FA. Cows fed WS tended to present a higher concentration of UFA in milk when compared with those fed CSFA. This study suggests that under some circumstances, abomasal flow of UFA in early lactation cows can be increased by supplementing their diet with fat supplements rich in linoleic acid, regardless of rumen protection, with small effects on ruminal DM digestibility.     

The use of principal component analysis (PCA) to characterize beef

Principal component analysis was performed to study the relationships between chemical, physical and sensory variables (n=18) measured on longissimus thoracis et lumborum of 79 young bulls from the following ethnic groups: hypertrophied Piemontese, normal Piemontese, Friesian, crossbred hypertrophied Piemontese×Friesian, Belgian Blue and White. The first three PCs explained about 63% of total variability. Sensory characteristics, protein content, shear force and cooking losses resulted the most effective variables for the PC1, while hydroxyproline and ether extract content, as well as hue and lightness were useful to define the PC2. The distribution of the objects on the axes of the first two PCs allowed the identification of two groups, the first one including meats of the hypertrophied animals (Piemontese and Belgian Blue and White) the second one including normal Piemontese and Friesian. However, a considerable variability within groups was noted. The crossbreds were placed between the two previous groups. In conclusion, PCA proved to be a very effective procedure to obtain a synthetic judgement of meat quality.     

The use of rapeseed screenings in diets for lactating cows and subsequent effects on milk yield and composition

This trial was to determine the effect of dietary rapeseed screenings on milk production, milk composition, and feed intake of lactating dairy cows. Pelleted rapeseed screenings were fed at 0, 7, and 14% of diet DM. Assignment of 36 multiparous Holstein cows was based upon parity and previous lactation performance. The experimental period was from parturition through wk 16 of lactation. The control ration had 3.1% ether extract, whereas the ration with 14% rapeseed screenings had 5.4% ether extract. The rapeseed screenings contained 52.2% of C18:1 and 24.2% of C18:2 as percentage of total fatty acids. There were no significant effects of dietary treatment on milk yield or feed intake. There were significant increases in milk fatty acids C18:1 and C18:2 for cows consuming the diets with rapeseed screenings. Treatment did not significantly affect milk protein percentage as measured by Kjeldahl N or by the infrared method. Increased unsaturated fatty acids in the milk of cows fed rapeseed screenings had no apparent effect on infrared fat analysis. There was no interaction of treatment and milk fat analysis method (infrared versus Babcock). Dietary treatment did not affect blood serum nonesterified fatty acid concentrations over the 16-wk period. In conclusion, rapeseed screenings, fed at levels up to 14% of the diet, did not affect milk yield, milk protein, or milk fat percentage but did change milk fatty acid composition.     

Effect of canola fat on ruminal and total tract digestion, plasma hormones, and metabolites in lactating dairy cows.

The effects of canola fat on digestion and metabolism were investigated by incorporating 0, 4.5, 9, 13.2, or 17.4% Jet-Sploded canola seed into a diet containing a 60:40 (DM) concentrate:forage ratio. The diets contained 16.5% CP, 30% alfalfa silage, and 10% whole-crop oat silage on a DM basis and were fed for ad libitum consumption as TMR to 10 ruminally cannulated Holstein cows in early lactation. Jet-Sploded canola seed supplementation did not change ruminal pH or NH3 N concentrations, but VFA concentrations declined with increasing level of inclusion. Apparent digestibilities of DM, OM, CP, NDF, and ADF were unaffected by level of inclusion of Jet-Sploded canola seed, but ether extract digestibility declined linearly, which resulted in similar ether extract absorption across the three diets supplemented with canola fat. Based on in sacco data, the percentages of ruminal digestion of OM and CP declined with increasing inclusion of Jet-Sploded canola seed. Plasma glucose and FFA concentrations tended to respond in a quadratic fashion, plasma insulin concentration declined linearly, and plasma glucagon and somatotropin concentrations were unaffected by dietary treatment. The results indicate that a positive productive response may be expected from dietary inclusion of about 5% Jet-Sploded canola seed, but the benefits of increased energy density associated with higher inclusion levels may be offset by reduced availability of energy in the rumen and decreased fat digestibility postruminally. The substantial effects of time postfeeding on ruminal fermentation and on concentrations of plasma hormone and metabolites in animals fed TMR demonstrate that infrequent sampling can result in misleading results and, thus, invalid interpretation of the influence of dietary fat on these parameters.     

Carcass fat partitioning and meat quality of Alentejana and Barrosã young bulls fed high or low maize silage diets

This study assessed the effect of breed and diet on carcass composition, particularly fat partitioning, and meat quality in young bulls. An experiment with forty young bulls from two phylogenetically distant Portuguese bovine breeds, Alentejana and Barrosã, fed two diets with different maize silage to concentrate ratios, but isoenergetic and isonitrogenous, was carried out until the animals reached 18 months of age. In the longissimus lumborum muscle, Barrosã bulls fed the low silage diet had the highest intramuscular fat (IMF) content. Bulls fed the low silage diet also had the highest IMF content in the semitendinosus muscle. Diet determined the proportions of total visceral fat and individual fat depots. Under these experimental conditions, it was shown that the genetic background is a major determinant of carcass composition and meat quality, and that the dietary differences studied had limited effect on carcass composition.     

Effects of tomato pomace supplementation on carcass characteristics and meat quality of fattening rabbits

The aim of this study was to determine how a feeding plan characterized by different levels of tomato pomace (TP) supplementation influences the carcass characteristics, the chemical, physical and sensorial characteristics of rabbit meat. 144 weaned crossbred rabbits were divided into three groups of 48 each. The first group was fed a basal diet without TP, while the other two groups were fed the basal diet after replacing part of the diet with TP at 3% and 6%, respectively. There was a significant difference between the experimental groups in terms of live and carcass weights. The meat of rabbits fed on a 6% TP diet exhibited higher yellowness (b*) and Chroma values when compared to others. The saturated fatty acid content in the longissimus dorsi muscle and perirenal fat decreased significantly with increasing TP inclusion, while polyunsaturated fatty acids increased. Furthermore, our results indicate that a diet integrated with 6% TP could influence positively the overall preference of cooked meat.     

Effect of feeding restricted amounts of a medium- and high-protein diet on growth and body composition of ducklings

A total of 216 ducklings of mixed sex were fed diets containing either 19.5 or 24.7% crude protein, either to appetite or to 85% of appetite, from 1 to 21 or 24 days of age. There were no significant interactions between dietary protein content and level of feeding. At 21 days ducklings fed the high-protein diet were 28% heavier than those fed the medium-protein diet and birds fed the higher level of intake were 17% heavier than restricted groups. At 24 days the body weight of restricted ducklings was similar to that of those fed the higher level of intake at 21 days. From 1 to 21 days efficiency of food utilisation was better for ducks fed the high rather than the medium protein diet, but similar for the two levels of food intake. Efficiency of the restricted groups in the 1 to 24 days period was slightly worse than that of groups of similar body weight fed the higher level of intake from 1 to 21 days. At 21 days carcasses of ducklings fed the high protein diet contained 31% dry matter, of which 34% was fat and 53% was protein, compared with 34% dry matter in the carcasses from the medium protein groups, of which 41% was fat and 48% was protein. Feed restriction had no effect on carcass dry matter and the reduction in percentage ether extract was only about half the magnitude of the reduction due to dietary protein level. Dietary treatments had no significant effect on percentage protein in fat-free dry matter. At 24 days carcasses of restricted ducklings contained more dry matter but the proportions of ether extract and crude protein were similar to those in younger (21 days) ducklings of similar body weight fed at the higher level of food intake.     

Influence of dietary fat on pork eating quality

This study compared the influence of dietary fat sources on meat quality, fatty acid composition and sensory attributes in pork. The experiment was conducted with 43 entire male pigs (Pietrain×(Landrace×Large White)) which were fed a basal diet without added fat (control diet) or supplemented with different sources of fat: animal fat (1%, AF1; 3%, AF3), soyabean oil (1%, SBO1) and calcium soaps of palm oil (1%, CaSPO1). Dietary fat supplementation did not significantly affect ultimate pH, colour, Warner-Bratzler shear force values, sensory attributes or SFA. Pigs fed SBO1 had the lowest proportion of MUFA and the highest of PUFA. In conclusion, these dietary fat sources could be recommended for inclusion in diets, at these levels, with no detrimental effect on eating quality. Despite finding no significant differences, the PCA afforded a comprehensive view of the predominating attributes of pork from animals fed the different fats.     

Influence of dietary vitamin C and selenium,alone and in combination,on the composition and oxidative stability of meat of broilers

Information on the combined effect of dietary vitamin C and Se on the composition and oxidative stability of meat of broilers is not available in the literature. In the present experiment, male broiler chickens were fed a maize–wheat–soya diet supplemented with vitamin C at 280 and 560 mg/kg of diet, and Se (sodium selenite or selenised yeast; Se) at 0.3 mg/kg for 5 weeks. After slaughter, samples of thigh meat were analysed. The supplementation of diets with vitamin C or Se increased the protein concentration of the meat at the expense of fat. Vitamin C supplementation increased the vitamin C content of the meat in a dose-dependent manner and decreased the vitamin A concentration in the meat of broilers fed diets with sodium selenite or without a Se supplement. In the meat of the broilers that were fed these diets, the vitamin C decreased the lipid oxidation in meat that was stored for 5 days. No sparing effect of vitamin C was apparent on the amount of vitamin E in the meat. Selenised yeast was more effective in the enrichment of meat with Se than was selenite. Both Se sources increased the activity of glutathione peroxidase and the oxidative stability of the meat.     

Ruminant fat volatiles as affected by diet. A review

Volatile compounds in meat have been widely studied for their favourable or undesirable effects on meat flavour, or for their potential use in tracing the animal feeding system. To date, the chemical mechanisms causing the appearance of volatile compounds in meat have been largely understood. Several variables are involved in the accumulation of volatiles in animal tissues and among them animal diet plays a key role. The purpose of the present review is to highlight the effects of different dietary regimes (concentrate, green grass and fat-enriched diets) on the appearance of fat volatile compounds in ruminant meat. Grain-based diets induce greater accumulations in meat of branched-chain fatty acids, some aldehydes, and lactones while meat fat from grazing animals contains high levels of phenols, terpenes, indoles and sulphur compounds. Fat-enriched diets exert their effect mainly on those volatiles which originate from polyunsaturated fatty acids. Cooking procedures have been considered for their contribution to fat volatiles in meat by reactions induced by high temperatures.     

Feeding high oleic acid soybeans in place of conventional soybeans increases milk fat concentration

It is well established in the literature that feeding free vegetable oils rich in oleic acid results in greater milk fat secretion than does feeding linoleic-rich oils. The objectives of these experiments were to analyze the effects of oleic and linoleic acid when fed in the form of full-fat soybeans and the interaction between soybean particle size and fatty acid (FA) profile. Soybeans were included in diets on an iso-ether extract basis and diets were balanced for crude protein using soybean meal. Experiment 1 used 63 cows (28 primiparous, PP; 35 multiparous, MP) housed in a freestall barn with Insentec roughage intake control gates (Marknesse, the Netherlands). Cows were divided into 4 mixed parity groups within the same pen. Two groups were assigned to each of the 2 diets: whole raw Plenish (WP, high oleic; Dupont-Pioneer, Johnston, IA) soybeans or whole raw conventional (WC, high linoleic) soybeans. The MP cows exhibited significantly increased milk fat yield on the WP diet compared with the WC diet. A significantly greater C18 milk FA yield by the MP cows fed WP was observed compared with those fed WC, but no difference was present in the C16 or short-chain FA yield. No effects were seen in the PP cows. Experiment 2 used 20 cows (10 PP, 10 MP) in 2 balanced 5 × 5 Latin squares within parity. Cows received 5 diets: raw WP and WC diets, raw ground Plenish and conventional soybean diets (GP and GC, respectively), and a low fat control. A significant benefit was found for the GP diet compared with the GC diet for milk fat concentration and yield. In experiment 2, no difference was observed between cows fed the WP compared with the WC diet. In experiment 2, cows consuming the Plenish diets produced less milk than when consuming the conventional soybean diets. The soybean diets resulted in significantly more C18 and less <C18 FA compared with the low fat diet. The GP diet resulted in significantly more C18 FA than the GC diet and the ground soybeans resulted in less C16 FA compared with whole soybeans. In both experiments, cows fed the Plenish diets exhibited decreased trans-10 18:1, a FA often increased during milk fat depression, compared with those fed the conventional soybean diets, though differences were not observed in trans-10,cis-12 conjugated linoleic acid. These results indicate that feeding whole soybeans rich in oleic acid may result in some increased milk fat secretion compared with conventional whole soybeans containing high levels of linoleic acid. This advantage is clear for ground high-oleic soybeans compared with ground conventional soybeans.     

Purified berry anthocyanins but not whole berries normalize lipid parameters in mice fed an obesogenic high fat diet

Male C57BL/6 mice received diets with either 10% of kcal from fat, or a high fat diet [45% (HF45) or 60% (HF60) kcal from fat]. Diets were prepared with or without freeze‐dried powders (10%) from whole blueberries (BB), strawberries (SB), Concord grape or black raspberry. In the 2nd study, purified anthocyanins (ACNs) from SB or BB were added to the drinking water of the treatments fed the HF60 diet. In Study 1, serum triglycerides were increased by feeding the HF45 diet but were elevated further when black raspberry or BB was included in the HF45 diet. Liver total lipids and triglycerides were increased in mice fed HF45 diet and inclusion of any of the berry powders in the HF45 diet did not alter concentrations compared to HF45 controls. In the 2nd study, mice fed the HF60 diet plus purified ACNs from BB in the water had lower body weight gains and body fat than the HF60 fed. Serum cholesterol and triglyceride levels were elevated with the HF60 diet and decreased to control levels when ACNs from either SB or BB were included in the drinking water. Serum leptin levels were consistently decreased to control low fat levels in those ACN treatments in which measures of body fat were decreased. Administering purified ACNs from BB and strawberry via drinking water prevented the development of dyslipidemia and obesity in mice, but feeding diets containing whole berries or purple corn (PC) ACNs did not alter the development of obesity.     

Effects of Adding Fat and Lasalocid to Diets of Dairy Cows

Holsteins (n = 12) and Jerseys (n = 12) averaging 90 d postpartum were fed 70 d in a 2 × 2 × 2 factorial arrangement of breeds and diets containing 3.0 or 6.8% ether extract with or without 36.7 mg/kg lasalocid in the diet DM. For many variables, the breeds responded differently. Holsteins usually performed better on high fat diets without lasalocid and Jerseys responded better to lasalocid. Influence of increased dietary fat generally was small except when fat acted synergistically with lasalocid. Dry matter intake was depressed substantially only when lasalocid was added to the higher fat diet. This detrimental effect precipitated a reduction in milk production. Dietary lasalocid reduced 4% FCM yield, milk fat percent, and milk fat yield without any lasalocid × fat interactions on these variables; however these reductions were much larger with Holsteins than Jerseys. Feeding lasalocid decreased ruminal acetate and increased ruminal propionate, but the changes were smaller with Jerseys. Higher fat diets increased serum cholesterol, but increases were less with Jerseys than with Holsteins. After 56 d of feeding, increased dietary fat and lasalocid had little influence on digestibility of feed nutrients. Adaptation to lasalocid feeding appeared to be gradual and prolonged, extending beyond 35 d. Results suggest no economically important beneficial synergistic effects from feeding added fat plus lasalocid to lactating dairy cows.     

Conjugated linoleic acid content of milk and cheese from cows fed extruded oilseeds

Extruded oilseeds were fed to 24 dairy cows to study the influence on the conjugated linoleic acid content of milk and cheese. Cows were fed one of three diets that contained forage and grain in a ratio of 47:53. A control diet containing 13.5% soybean meal was compared with diets containing 12% full fat extruded soybeans or 12% full fat extruded cottonseed. The control, extruded soybean, and extruded cottonseed diets contained 2.73, 4.89, and 4.56% fatty acids, respectively. Measurements were made during the last 5 wk of the 8-wk experiment. The DM intakes and 3.5% fat-corrected milk yields were higher for cows fed the extruded soybean and extruded cottonseed diets than for cows fed the control diet. A tendency for lower fat and protein contents in the milk of cows fed the extruded soybean and extruded cottonseed diets was detected. Most of the C18 fatty acids were increased in the milk and cheese when extruded soybeans and cottonseeds were fed. The conjugated linoleic acid content in milk and cheese increased a mean of 109% when full fat extruded soybeans were fed and increased 77% when cottonseeds were fed compared with the conjugated linoleic acid content when the control diet was fed. Processing the milk into cheese did not alter the conjugated linoleic acid content. The conjugated linoleic acid content of milk and cheese can be increased by the inclusion of full fat extruded soybeans and full fat extruded cottonseeds in the diets of dairy cows.     

INFLUENCE OF LOW FAT FISHMEAL ON FATTY ACID COMPOSITION AND SENSORY QUALITY OF PORK

Four groups of growing-finishing pigs, were fed low fat fishmeal together with an increased level of fish oil. Additional fish oil increased the content of long-chain n-3 fatty acids in subcutaneous fat and muscle when feeding up to 9 g fish oil kg^-1 diet. Sensory quality of fresh meat was not affected by the increased level of fish oil in diets but the intensity of off-flavor/odor and rancid flavor/odor of fat increased after six months of frozen storage. Partial least square regression of rancid flavor/odor after six months of frozen storage using the significant variables C20:1, C20:5 (EPA), C22:5 (DPA) and C22:6 (DHA) in subcutaneous fat gave correlation coefficients as high as 0.92. Based on these results, the use of low fat fishmeal is acceptable but the content of fish oil should be limited to 3 g fish oil kg^-1 diet for growing-finishing pigs.     

Total replacement of corn silage with sorghum silage improves milk fatty acid profile and antioxidant capacity of Holstein dairy cows

Total mixed rations containing corn silage (CS) or forage sorghum silage (SS) were fed to mid-lactation Holstein cows to determine the effects on feed intake, lactation performance, milk composition and fatty acid profile, nutrient digestibility, blood metabolites, rumen microbial N synthesis, and antioxidant status. The experiment was designed as a 2-period change-over (two 28-d periods) trial with 2 diets including CS diet or SS diet and 12 cows. Total replacement of CS with SS had no significant influence on dry matter intake. Substituting CS with SS had no effect on milk production, feed efficiency, and milk concentrations of fat, protein, lactose, and solids-not-fat, whereas yields of milk fat, protein, and lactose were greater for cows fed the CS diet. Blood parameters including glucose, albumin, cholesterol, triglyceride, total protein, urea N, and fatty acids were not affected by the dietary treatments. Apparent digestibility coefficients of dry matter, organic matter, crude protein, ether extract, neutral detergent fiber, and acid detergent fiber were not significantly influenced by the diets. Replacing CS with SS had no effect on total saturated fatty acids and total monounsaturated fatty acids, whereas total polyunsaturated fatty acid percentage was greater with the SS diet. Proportions of C20:0, C18:3n-3, and C18:3n-6 were affected by feeding SS. Cows fed CS had a greater amount of urinary purine derivatives. Feeding SS had a positive effect on total antioxidant capacity of blood and milk. In conclusion, SS can be fed to lactating Holstein cows as a total replacement for CS without undesirable effects on animal performance, but with positive effects on antioxidant capacity and polyunsaturated fatty acids of milk. This forage can be an excellent choice for dairy farms in areas where cultivation of corn is difficult due to water shortage.