首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Early lactating cows mobilize adipose tissue (AT) to provide energy for milk yield and maintenance and are susceptible to metabolic disorders and impaired immune response. Conjugated linoleic acids (CLA), mainly the trans‐10, cis‐12 isomer, reduce milk fat synthesis and may attenuate negative energy balance. Circulating glucocorticoids (GC) are increased during parturition in dairy cows and mediate differentiating and anti‐inflammatory effects via glucocorticoid (GR) and mineralocorticoid receptors (MR) in the presence of the enzyme 11β‐hydroxysteroid dehydrogenase type 1 (11βHSD1). Activated GC are the main ligands for both receptors in AT; therefore, we hypothesized that tissue‐specific GC metabolism is effected by varying amounts of GR, MR and 11βHSD1 and/or their localization within AT depots. Furthermore, the lipolytic and antilipogenic effects of CLA might influence the GC/GR/MR system in AT. Therefore, we aimed to localize GR and MR as well as the expression pattern and activity of 11βHSD1 in different AT depots during early lactation in dairy cows and to identify potential effects of CLA. Primiparous German Holstein cows were divided into a control (CON) and a CLA group. From day 1 post‐partum (p.p.) until sample collection, the CLA group was fed with 100 g/d CLA (contains 10 g each of the cis‐9, trans‐11 and the trans‐10, cis‐12‐CLA isomers). CON cows (n = 5 each) were slaughtered on day 1, 42 and 105 p.p., while CLA cows (n = 5 each) were slaughtered on day 42 and 105 p.p. Subcutaneous fat from tailhead, withers and sternum, and visceral fat from omental, mesenteric and retroperitoneal depots were sampled. The localization of GR and 11βHSD1 in mature adipocytes – being already differentiated – indicates that GC promote other effects via GR than differentiation. Moreover, MR were observed in the stromal vascular cell fraction and positively related to the pre‐adipocyte marker Pref‐1. However, only marginal CLA effects were observed in this study.  相似文献   

2.
This study was performed to investigate the hypothesis that supplementation of conjugated linoleic acid (CLA) changes the concentrations of retinol and tocopherols in the milk of cows. To investigate this hypothesis, Holstein cows received daily from 3 weeks ante‐partum to 14 weeks post‐partum either 172 g of a CLA‐free rumen‐protected control fat (control group, n = 20) or the same amount of a rumen‐protected CLA fat, supplying 4.3 g of cis‐9, trans‐11 CLA and 3.8 g of trans‐10, cis‐12 CLA per d (CLA group, n = 20). Milk samples (collected at weeks 1, 3, 5, 8 and 11 of lactation) were analysed for retinol, α‐ and γ‐tocopherol concentrations. Milk of cows supplemented with CLA had higher concentrations of retinol (+34%), α‐tocopherol (+44%) and γ‐tocopherol (+21%) than milk of control cows (p < 0.05). The daily output of these vitamins via milk was also greater in cows of the CLA group than in cows of the control group (+36, 50 and 24% for retinol, α‐tocopherol and γ‐tocopherol, respectively, p < 0.05). In agreement with higher concentrations of tocopherols, concentrations of thiobarbituric acid‐reactive substances, determined in milk of week 5, were lower in cows of the CLA group than in control cows, indicative of a lower susceptibility of milk lipids to peroxidation. Plasma concentrations of retinol and α‐tocopherol, determined at 1 and 5 weeks post‐partum, were not different between the two groups of cows. In conclusion, this study shows that supplementing dairy cows with a moderate amount of CLA causes an increase of the concentrations of vitamins A and E in the milk and results in an increased output of those vitamins via milk. These effects might be beneficial with respect to the nutritional value of dairy products and the susceptibility of milk fat to oxidative deterioration.  相似文献   

3.
We evaluated the lactation performance, liver lipid content and plasma metabolites indicating the energy balance of dairy cows supplemented with conjugated linoleic acid (CLA) pre‐ and post‐partum (PP) vs. only PP. A total of 60 cows were divided into three groups (n = 20). Daily diet of cows was supplemented with 14 g of CLA (7 g cis‐9, trans‐11 and 7 g trans‐10, cis‐12 isomers) from week 3 before the expected date of calving (group CLA1), or from the day of calving (group CLA2) until 77–91 days PP. Control cows were fed an isocaloric, isonitrogenous and isolipidic diet without CLA. Between week 3 and week 6 PP, the milk yield of cows in both CLA‐treated groups was approximately 4.5 kg higher (p < 0.05) than in control. Milk fat concentrations decreased from week 3 and were lower in both CLA groups than in control (p < 0.01). Body condition score loss was lower (p < 0.05) in the CLA1 than in the control group on week 5 PP. By week 11 PP, the body condition of both CLA1 and CLA2 groups exceeded that of control. Plasma non‐esterified fatty acid was lower in CLA1 compared to CLA2 and control during the early PP period (p < 0.05), while this difference faded away by the late PP period. Beta‐hydroxybutyrate (BHBA) increased rapidly in all groups following calving. In CLA1 group, it began to decrease sooner than in CLA2 and control. The prevalence of subclinical ketosis (BHBA > 1.2 mm ) was lower in CLA1 group than in CLA2 and control (p < 0.05). Liver biopsy analyses showed that CLA1 treatment decreased (p < 0.05) the total lipid content of liver compared to control at week 5 after calving. Our results show that CLA supplementation is more efficient in alleviating body mass mobilization and decreasing the incidence of subclinical ketosis when applied as early as 3 weeks before calving than started feeding after calving.  相似文献   

4.
The objective of this study was to investigate the effects of pistachio by‐products (PBP) on nutrient digestibility, blood metabolites and milk fatty acid (FA) profile in Saanen dairy goats. Nine multiparous lactating Saanen goats (on day 90 post‐partum, 45 ± 2/kg BW) were randomly assigned to a 3 × 3 Latin square design with three treatment diets: 1) control diet (alfalfa hay based), 2) 32% PBP and 3) 32% PBP + polyethylene glycol (PEG‐4000; 1 g/kg dry matter). Each period lasted 21 days, including 14 day for treatment adaptation and 7 day for data collection. Pistachio by‐products significantly decreased (p < 0.01) crude protein (CP) digestibility compared with the control diet (64.4% vs. 58.7%), but PEG addition did not differ for CP digestibility of goats fed 32% PBP + PEG and those fed the two other diets. The digestibility of NDF tended (p = 0.06) to decrease for goats fed PBP compared with those fed the control diet. Yields of milk and 4% fat‐corrected milk were not affected by dietary treatments. Compared with the control diet, PBP supplementation appreciably changed the proportions of almost all the milk FA measured; the main effects were decreases (p < 0.01) in FA from 8:0 to 16:0 and increases (p < 0.01) proportions of cis‐9, trans‐11 18:2 and trans‐11 18:1, monounsaturated FA, polyunsaturated FA and long‐chain FA. The saturated FA, short‐chain FA and medium‐chain FA proportions were lower (p < 0.01) in goats fed the two PBP supplemented diet than in those fed the control diet and PEG addition led to intermediate proportions of saturated FA, unsaturated and monounsaturated FA. Inclusion of PBP in the diet decreased (p < 0.01) plasma concentrations of glucose and urea nitrogen compared with the control diet. It was concluded that PBP can be used as forage in the diet of dairy goats without interfering with milk yield. Inclusion of 32% PBP in the diet of dairy goats had beneficial effects on milk FA profile but PEG addition to PBP did not contribute to enhance further milk FA profile.  相似文献   

5.
The objective of this study was to determine the energy balance in early lactating local goats when supplemented with conjugated linoleic acid. Fifteen local goats from the north‐east of Mexico were used. Three treatments were evaluated: (a) Control (Base diet); (b) CLA 50 g; and (c) CLA 90 g. The CLA was a mixture of micro‐encapsulated FA, which supplied c9, t11 and t10, c12. Goats had an adaptation period of 2 weeks and 7 experimental weeks. The variables evaluated were body weight, DMI, milk yield, and fat, protein, and lactose yield, FA milk profile, and energy balance. The analysis of the data was analyzed as repeated measures using the PROC MIXED procedure and Tukey test (p < .05). In milk of goats from the treatment 90 g of the isomer t10, c12 CLA (p < .05) the milk fat content and milk fat yield with respect to the control treatment were reduced and the energy balance was improved. In goats treated with 11 g of t10, c12 CLA increased (p < .05) milk yield and milk lactose content. These results suggest that energy not used to synthesize dairy fat was used to increase milk yield and improve energy balance.  相似文献   

6.
Trans10, cis12 conjugated linoleic acid (t10c12‐CLA) is well‐established in decreasing milk fat content and causing milk fat depression (MFD) in dairy cattle and goats. However, the detailed mechanisms of its effect are not completely understood. Therefore, we used goat mammary epithelial cells (GMECs) to further study the molecular mechanisms whereby t10c12‐CLA regulates milk fat synthesis. The optimal concentration of t10c12‐CLA (100 μmol/L) for cell culture was determined through a cell vitality and morphology assay, and evaluation of abundance of apoptosis‐related proteins. Oil red O stain indicated that t10c12‐CLA increased concentration of cytoplasmic lipid droplets. Furthermore, t10c12‐CLA increased the intracellular triacylglycerol (TG) content (P < 0.05). Among 16 genes related to lipid metabolism that were measured by quantitative real‐time PCR, t10c12‐CLA down‐regulated (P < 0.05) genes involved in de novo fatty acid synthesis including FASN, ACACA and SCD1, and also down‐regulated the protein expression of FASN and SCD1 but up‐regulated (P < 0.05) the expression of CD36 and ADRP. Overall, the data indicate that a side effect of de novo fatty acid synthesis inhibition by t10c12‐CLA is the up‐regulation of fatty acid uptake and accumulation of lipid droplets in GMECs. The biologic reason for such an effect merits further study.  相似文献   

7.
The objective of this study was to investigate the effects of tannins and saponins in Samanea saman on rumen fermentation, milk yield and milk composition in lactating dairy cows. Four multiparous early‐lactating dairy cows (Holstein‐Friesian cross‐bred, 75%) with an initial body weight (BW) of 405 ± 40 kg and 36 ± 8 day in milk were randomly assigned to receive dietary treatments according to a 4 × 4 Latin square design. The four dietary treatments were unsupplemented (control), supplemented with rain tree pod (S. saman) meal (RPM) at 60 g/kg, supplemented with palm oil (PO) at 20 g/kg, and supplemented with RPM at 60 g/kg and PO at 20 g/kg (RPO), of total dry matter (DM) intake. Cows were fed with concentrate diets at a ratio of concentrate to milk yield of 1:2, and chopped 30 g/kg of urea‐treated rice straw was fed ad libitum. The RPM contained condensed tannins and crude saponins at 88 and 141 g/kg of DM respectively. It was found that s upplementation with RPM and/or PO to dairy cows diets did not show negative effect on ruminal pH, blood urea nitrogen and milk urea nitrogen concentration (p > 0.05). However, supplementation with RPM resulted in lower ammonia nitrogen (NH3‐N) concentration (p < 0.05). In addition, propionic acid and milk production increased while acetic acid, acetic to propionic ratio, methane production, methanogens and protozoal population decreased with RPM and/or PO supplementation. Furthermore, addition of PO and RPO in the diets increased milk fat while supplementation of RPM resulted in greater milk protein and Fibrobacter succinogenes numbers (p < 0.05). The population of Ruminococcus flavefaciens and Ruminococcus albus were not affected by any treatments. The findings on the present study showed that supplementation with RPM and RPO to diets of cows improved the rumen environment and increased milk yield, content of milk protein and milk fat.  相似文献   

8.
The study tested the hypothesis that certain pastoral forages and olive by‐products, available in arid areas, may positively influence fatty acid composition and physicochemical properties of goat's milk. Thirty indigenous goats (body weight = 25.2 kg; age = 4.1 years) were allocated to three groups. During 60 days, the goats received ad libitum either dried olive leaves + Stipa tenacissima (group OL), khortane grass hay (group Ko) or oat hay (control diet, group OH). Milk samples were collected and analysed for total solids, fat, protein, lactose and ash content and fatty acid profile. Average milk yield did not statistically differ among groups. Milk total solids from OL group were higher in comparison with Ko and C groups (15.3, 14.7 and 14.5%, respectively; p < 0.05). Fat content was also higher for the OL group as compared to the other groups (5.44 vs. 5.01 and 4.66%, respectively, for Ko and OH). No significant differences were observed for the milk content of lactose, protein and ash. The percentage of saturated fatty acids of total milk fat was higher in OL and Ko groups compared to the C group (p < 0.001); the milk whereof was characterized by the highest percentage of monounsaturated (p < 0.01) and total unsaturated fatty acids. Milk fat of Ko and C groups showed significantly higher proportions of rumenic (CLA cis‐9 trans‐11) and vaccenic acids (C18:1 trans‐11) compared to OL milk. The feeding system based on Stipa tenacissima and dried olive leaves resulted in the milk lowest proportion of trans‐fatty acids and the highest proportion of polyunsaturated ω3‐fatty acids (p < 0.05).  相似文献   

9.
This experiment was conducted to determine whether increasing the net energy (NEL) of a total mixed ration (TMR) with mainly unsaturated fat from corn distillers dried grains with solubles (DDGS) vs. rumen inert (RI)‐saturated fat has similar impacts on animal performance. The experiment was an incomplete Youden square with three treatments and four 28‐days periods, completed on a large commercial dairy using three early lactation pens each with approximately 380 multiparity cows. The TMR for all treatments was the same, except for 150 g/kg dry matter (DM) of each TMR which contained 90 g/kg high‐protein DDGS (HPDDGS) and 60 g/kg beet pulp (i.e. low‐fat control diet; LFC); 150 g/kg DDGS (i.e. high‐fat diet with unsaturated fat; HFU); or 111 g/kg HPDDGS, 20 g/kg beet pulp and 19 g/kg RI fat (i.e. high‐fat diet with saturated fat; HFS). The DM intake was highest (p < 0.05) for HFU‐fed cows. Milk, fat and true protein yields, as well as milk energy output, were higher (p < 0.01) when cows were fed HFS vs. HFU and LFC diets. Milk true protein concentration was lowest (p < 0.01) for HFS‐fed cows, but milk fat % was lowest (p < 0.01) for HFU and highest (p < 0.01) for HFS‐fed cows. There were numerous differences (p < 0.01) in milk fatty acid levels amongst diets. The increase in body condition score was lowest (p < 0.01) for LFC. Whole tract digestibility of acid detergent fibre was lower (p < 0.01) for LFC vs. HFS cows, and fat digestion was lowest (p < 0.01) for LFC‐fed cows. This DDGS, high in unsaturated fatty acids, was fed at high levels (i.e. 152 g/kg DM) with little impact on animal performance vs. a lower fat control diet, although addition of an RI‐saturated fat to create a diet with a similarly higher fat level resulted in higher animal productivity.  相似文献   

10.
The objective of this study is to examine whether CLA would help to improve negative responses in lactating cows during heat stress. During a 2-week adjustment period, all cows were fed a control diet supplemented with 400 g of calcium salts of palm oil fatty acids. After the adjustment period, cows (n = 9 per group) were randomly assigned by block to one of four treatments: control or three diets containing 100, 200, or 400 g of CLA (70% of which were mixed isomers of CLA). Milk fat percentage and yield decreased by supplementation of CLA (P < 0.01), but milk yield and other nutrient components did not vary (P > 0.05). The concentrations of short and medium-chain fatty acids (C4–C14) decreased and long-chain fatty acids (C18) increased in milk fat for cows fed CLA. Moreover, the contents of cis9, trans11 and trans10, cis12-CLA in milk fat increased markedly (P < 0.01). Respiration rate was lower (P < 0.05) for cows fed 200 g of CLA and rectal temperature decreased (P < 0.01) in all CLA groups during day 15 to day 28. Contents of aspartate aminotransferase, creatine kinase, thyroxin, potassium, sodium, calcium and chlorine were altered by CLA supplements, whereas other plasma parameters were not affected (P > 0.05). Lower concentrations of aspartate aminotransferase and creatine kinase in blood for cows fed 200 g or 400 g of CLA suggested that CLA protected cows from muscle damage. In addition, higher concentrations of electrolytes and thyroxin in blood in these groups suggested that CLA could improve heat stress situations in cows. Overall, the results showed that supplementations with 200 or 400 g/day of CLA moderated the negative responses in heat-stressed cows.  相似文献   

11.
A study with finishing lambs assessed the effect of dietary inclusion of Prosopis laevigata pods (PLPs) on performance, carcass characteristics, meat traits and fatty acid profile of subcutaneous fat. Twenty‐one Rambouillet lambs (27.0 ± 3.0 kg BW) were assigned to one of three experimental diets with 0, 150 and 300 g PLP/kg DM. Evaluation of growth performance lasted 49 days. The experimental design was completely randomized and analysed with a mixed model. Lambs fed diets with 0, 150 and 300 g PLP had similar growth performance. Lambs fed diets with 300 g PLP/kg DM had better (p < 0.05) carcass yield and classification, less (p < 0.05) fat deposition and lower lightness (L*) value (p < 0.05) in meat than lambs fed diets with 0 and 150 g PLP/kg DM. Saturated fatty acids (palmitic and stearic) decreased (p < 0.05) and unsaturated fatty acids (oleic and linoleic) increased (p < 0.05) in subcutaneous fat of lambs fed diets with 150 and 300 g pods as compared with lambs not fed PLP. Prosopis laevigata pods are a safe feedstuff that can replace a third of conventional ingredients and reduce feed costs in growing lambs. Addition of PLP reduced (p < 0.05) total feed cost by 21%.  相似文献   

12.
Supplementing conjugated linoleic acid ( CLA ) is supposed to spare glucose due to the milk fat‐depressing effect of the trans ‐10, cis ‐12 CLA isomer, and allows repartitioning nutrients despite an energy deficiency in early lactation. However, there is still a lack of knowledge in terms of the dynamic pattern of the glucose turnover in transition dairy cows. We hypothesized that dairy cows supplemented with CLA have an altered rate of glucose turnover and insulin sensitivity during early lactation. We conducted three consecutive hyperglycaemic clamps (HGC ) in weeks ?2, +2 and +4 relative to parturition in Holstein cows supplemented daily either with 70 g of lipid‐encapsulated CLA (6.8 g trans ‐10, cis ‐12 and 6.6 g of the cis ‐9, trans ‐11 CLA isomer; CLA ; n  = 11) or with 56 g of control fat ( CON ; n  = 11). From week ?3 up to week +4 relative to parturition, milk yield and dry matter intake (DMI ) were recorded daily, while body weight (BW ) and milk composition were obtained once weekly. Blood samples were taken once weekly and every 30 min during the HGC . Plasma was analysed for concentrations of glucose, fatty acids (FFA ), beta‐hydroxybutyrate (BHB ), insulin, triglycerides and cholesterol. The CLA supplementation did not affect performance and metabolic parameters except for BHB and cholesterol. Furthermore, insulin concentrations and insulin sensitivity were affected by treatment. During the HGC in early lactation, insulin response was lower and decrease in FFA and BHB greater compared with the HGC in week ?2 although glucose target concentration achieved during the steady‐state period was similar for all three HGC . Our findings in terms of insulin and cholesterol suggest that body reserves are preserved through CLA feeding without restraining animal's performance. Furthermore, CLA effects on cholesterol and triglyceride concentrations indicated beneficial effects on hepatic lipid export contributing to an improved efficiency of prevailing metabolites in circulation.  相似文献   

13.
The absorption and metabolism of vitamin A is linked with that of lipids. It is known that conjugated linoleic acid (CLA) affects the lipid metabolism in growing and lactating animals. In the present study, the hypothesis was investigated that dietary CLA influences vitamin A status of lactating rats and their pups during the suckling period. For this purpose, Wistar Han rats were fed either a control diet (control group, n = 14) or a diet containing 0.87% of cis‐9, trans‐11 and trans‐10, cis‐12 (1:1) CLA (CLA group, n = 14) during pregnancy and lactation. Vitamin A concentrations in various body tissues were determined 14 days after delivery in dams and 1, 7 and 14 days after birth in pups, and expression of selected genes involved in metabolism of retinoids was determined in dams. Vitamin A concentrations in liver, plasma and muscle were similar in control and CLA‐fed dams. Expression of genes involved in retinoid transport, storage and degradation in liver and adipose tissue in dams was also not different between control and CLA‐fed dams. Vitamin A concentrations in milk curd, sampled at d 1, 7 and 14 of lactation were not different between control and CLA‐fed dams. Vitamin A concentrations in liver, lung and adipose tissue were also not different in pups from control dams and pups from CLA‐fed dams. In conclusion, we show for the first time that dietary CLA has little effect on vitamin A concentrations and vitamin A metabolism in lactating rat dams and, moreover, does not influence tissue vitamin A concentrations in their newborn and suckling pups.  相似文献   

14.
The objective of this trial was to investigate the influences of conjugated linoleic acid (CLA ) and vitamin E (Vit. E) and their interactions on fatty acid composition and vitamins in milk (α‐tocopherol, retinol and β‐carotene) as well as on α‐tocopherol in blood of pluriparous cows from week 6 ante partum until week 10 post‐partum (p.p.). We assigned 59 pluriparous German Holstein cows to four treatment groups with the treatment factors CLA and Vit. E at two levels in a 2 × 2 factorial design. Milk fatty acid composition and milk vitamins were analysed on lactation days 7 and 28. α‐tocopherol in blood serum was analysed on days ?42, ?7, 1, 7, 14, 28 and 70 relative to parturition. Milk concentration of α‐tocopherol was influenced by Vit. E (p  < .001) and CLA (p  = .034). Percentage of cis ‐9, trans ‐11 CLA in total milk fat was influenced by treatment with CLA (p  < .001), while for percentage of trans‐ 10, cis ‐12 CLA an interaction between treatment and day (p  = .019), driven by an increase in both CLA groups from day 7 to day 28, was found. Serum ratios of α‐tocopherol to cholesterol were influenced by Vit. E (p  < .001). Results suggest that treatment with CLA during late pregnancy and early lactation is suitable to enhance the proportion of trans‐ 10, cis ‐12 CLA in milk and thereby influencing nutritional properties. As treatment with Vit. E did not have an impact on milk fatty acid composition, it might be possible to increase the antioxidative capacity of the dairy cow without affecting milk properties. Consequently, combined treatment with CLA and Vit. E might elicit synergistic effects on the cow and milk quality by increasing the proportion of CLA in milk fat as well as the excretion of Vit. E and the Vit. E levels in serum.  相似文献   

15.
Multiparous early lactation Holstein cows (n = 16) were used in a randomized complete block design to determine the effects of feeding fatty acid calcium and the interaction of forage quality on production performance and biochemical indexes in early lactation cow. Treatments were as follows: (i) feeding low‐quality forage without supplying fatty acid calcium (Diet A), (ii) feeding low‐quality forage with supplying 400 g fatty acid calcium (Diet B), (iii) feeding high‐quality forage without supplying fatty acid calcium (Diet C) and (iv) feeding high‐quality forage with supplying 400 g fatty acid calcium. This experiment consisted 30 days. The milk and blood samples were collected in the last day of the trail. Intakes were recorded in the last 2 days of the trail. Supplementation of fatty acid calcium decreased significantly dry matter intake (DMI) (p < 0.01). Addition fatty acid calcium decreased milk protein percentage (p < 0.01) and milk SNF percentage (p < 0.01), but increased MUN (p < 0.05). Supplemented fatty acid decreased concentration of blood BHBA (p < 0.05), but increased TG, NEFA, glucagon, GLP‐1, CCK, leptin, ApoA‐IV, serotonin and MSH concentration in blood, the CCK concentration and feed intake showed a significant negative correlation (p < 0.05).  相似文献   

16.
This study was conducted to investigate the effects of processing method (grinding vs. steam flaking) and increasing densities of steam‐flaked barley grain on dry matter intake (DMI), rumen pH and fermentation characteristics, digestibility of dry matter in the total digestive tract (DDTT), and milk production of dairy cows. Eight multiparous mid‐lactation Holstein cows averaging 103 ± 24 DIM, 44.5 ± 4.7 kg milk/day and weighing 611 ± 43 kg at the start of the experiment were used in a replicated 4 × 4 Latin square design with 21‐day periods. Cows were fed diets consisting of (DM basis) 23.8% corn silage, 13.5% chopped alfalfa hay and 62.7% concentrate. The dietary treatments were either ground barley (GB) using a hammer mill or steam‐flaked barley (SFB) – varying density at 390, 340 or 290 g/l. Processing method (GB vs. SFB) did not affect DMI (23.6 kg/day on average), DDTT (71.0% on average), milk yield (43.4 kg/day on average), milk components, rumen pH and molar proportions of acetate, propionate, butyrate and sorting activity. Ruminal isovalerate concentration tended (p = 0.06) to be higher for cows fed GB than those fed SFB‐based diets. Decreasing the density of SFB from 390, 340 to 290 g/l tended to linearly increase DMI (p = 0.09), decrease total solids percentage of milk (p = 0.10) and linearly decreased milk urea nitrogen (12.8, 12.4 and 12.1 mg/dl; p = 0.04); also, the sorting index (SI) of the particles retained on the 19.0‐mm sieve without affecting the SI of the particles retained on 8.0‐mm, 1.18‐mm or passed through 1.18‐mm sieve (p = 0.05). These results indicated the limited effects of processing method (grinding vs. steam flaking) and densities of SFB (390, 290 or 290 g/l) on cows’ performance and feed utilization for dairy cows fed low‐forage diets. Therefore, both processing methods could be recommended under current feeding conditions of dairy cows.  相似文献   

17.
A number of studies have shown that the rumenic acid (RA = cis-9 trans-11 C18:2 CLA) content of milk fat is usually higher in sheep than in goats, due partly to different dietary regimens. An experiment was conducted with 12 lactating dairy ewes and 12 goats with the objective to compare the two animal species (sheep/goats) fed diet with the same forage/concentrate (F/C) ratio, on their milk fatty acids (FA) profile with emphasis on RA and vaccenic acid (VA) production. The experiment was carried out in three consecutive phases, lasted 3 weeks each, immediately after weaning of lambs and kids. In phase I, the ewes and the goats were fed according to their maintenance and lactation requirements, with 14 kg alfalfa hay, 4 kg wheat straw and 12 kg concentrate the 12 ewes (F/C ratio = 60/40), and with 14 kg alfalfa hay, 4 kg straw and 24 kg concentrate the 12 goats (F/C ratio = 43/57). In phase II, 14 kg alfalfa hay, 4 kg straw and 14 kg concentrate were offered daily to each group of sheep and goats, with a F/C ratio = 56/44. In phase III, all ewes and goats were fed individually with 0.8 kg alfalfa hay, 0.2 kg wheat straw and 0.8 kg concentrate daily with a F/C ratio = 56/44. The results showed that the different F/C ratio between sheep and goats diets, in phase I, changed significantly the milk FA profile, with no significant difference in RA and VA milk fat content between sheep and goats in phase I. In phases II (group feeding) and III (individual feeding), where sheep and goats fed with the same amount of food of the same F/C ratio, the sheep milk fat had higher RA and VA content compared to goats. In conclusion, these findings support the hypothesis that there are species differences, as RA and VA production concerns, which needs further investigation.  相似文献   

18.
The potential effect of dietary forage supplementation on the performance and rumen development in dairy calves is well established. However, limited research has been directed to the comparative effects of forage offering methods on calf performance. The objective of the present study was to determine the effects of forage provision methods (total mixed ration or free choice) on the performance, nutrient digestibility, rumen fermentation and nutritional behaviour in newborn calves. Forty‐five Holstein dairy calves (3 days of age and 41 ± 2 kg of body weight) were assigned to the following three groups (n = 15): (i) starter without forage provision (CON), (ii) starter supplemented with 10% alfalfa hay (AH) as a total mixed ration (AH‐TMR) and (iii) starter and AH as a free‐choice provision (AH‐FC) for a period of 70 days. All the calves were offered 5 l of milk/day from day 3 to 50, and 2.5 l/day from day 50 until weaning on day 56. Dry matter intake (DMI) was greater (p < 0.01) in the AH‐TMR and AH‐FC treatments than in the CON during the pre‐ and post‐weaning periods. Calves fed the AH‐FC diet showed the highest post‐weaning DMI among the treatments. The calves receiving ad libitum forage tended (p = 0.08) to increase crude protein digestibility and overall volatile fatty acids (VFA) concentrations in the rumen. No differences were observed among the treatments at the time spent on standing, lying, eating and performing non‐nutritive oral behaviours. Compared to CON calves, animals in the AH‐TMR treatment spent more time (p < 0.05) ruminating. In conclusion, our data suggest that forage supplementation in both forage offering methods increased total DMI, ruminal pH and ruminating time in dairy calves. Hence, there is no benefit in the free‐choice provision of AH in dairy calves.  相似文献   

19.
This study investigated the hypothesis that dietary supplementation of fish oil as a source of n‐3 polyunsaturated fatty acids (PUFA) influences the expression of target genes of sterol regulatory element‐binding proteins (SREBP)‐1 and (SREBP)‐2 involved in triacylglycerol (TAG) synthesis and fatty acid and cholesterol metabolism in the liver, and moreover activates the expression of target genes of peroxisome proliferation‐activated receptor (PPAR)‐α involved in TAG and fatty acid catabolism in liver and skeletal muscle. Twenty lactating sows were fed a control diet or a fish oil diet with either 50 g of a mixture of palm oil and soya bean oil (4:1, w/w) or fish oil per kg. The diet of the fish oil group contained 19.1 g of n‐3 PUFA (mainly 20:5 n‐3 and 22:6 n‐3) per 100 g of total fatty acids, while the diet of the control group contained 2.4 g of n‐3 PUFA (mainly 18:3 n‐3) per 100 g of total fatty acids. The fish oil group had reduced relative mRNA concentrations of various target genes of SREBP‐1 involved in fatty acid and TAG synthesis in comparison with the control group (p < 0.05). Relative mRNA concentrations of target genes of PPARα involved in fatty acid catabolism in both liver and muscle, and mRNA concentrations of target genes of SREBP‐2 involved in cholesterol synthesis and uptake were not influenced by fish oil supplementation. Concentrations of cholesterol and TAG in plasma, fat content of milk and weight gains of litters during the suckling period were not different between the two groups of sows. In conclusion, this study suggests that fish oil has only minor effects on hepatic lipid metabolism, which are non‐critical with respect to milk production in sows.  相似文献   

20.
The aim of this study was to evaluate the effects of high levels of whole raw soya beans in the diets of lactating cows. Twelve Holstein dairy cows were used, randomized in three 4 ×  4 balanced and contemporary Latin squares and fed the following diets: (i) control (C), without including whole raw soya beans; (ii) 80 g/kg in DM of whole raw soya beans (G80); (iii) 160 g/kg in DM of whole raw soya beans (G160); and (iv) 240 g/kg in DM of whole raw soya beans (G240). There was significant reduction (p < 0.05) in dry matter intake (kg/day) in cows supplemented with G240 compared with C (23.8 vs. 25.3 respectively). G240 diets presented lower crude protein digestibility (g/kg) (p < 0.05) in comparison with C diet (683 vs. 757 respectively). There was significant effect of experimental rations in nitrogen balance (p < 0.05), G240 diet presenting significant reduction in comparison with the other diets, and faecal excretion of nitrogen was higher for G240 diet. The concentration of ruminal ammoniacal nitrogen was significantly higher (p < 0.05) for cows receiving control diet, compared to other diets. G240 diet resulted in significantly lower milk and protein yield (p < 0.05) in comparison with C diet. Significant C18:2 cis fatty acids were observed in milk concentrations (p < 0.05) for G240 diet. The use of high level of whole raw soya beans in dairy cow diets improves the unsaturated fatty acid profile in milk, and the diets (G80 and G160) led to minor alterations in the digestive processes and animal metabolism.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号