Effects of dietary energy density and feeding strategy during the dry period on feed intake, energy balance, milk production, and blood metabolites of Holstein cows

Our study aimed to assess the effects of dietary energy density and strategy of delivery during the dry period on production and metabolic responses of Holstein cows free of displacement of abomasum, retained placenta, metritis, or hypocalcemia. Twenty-seven multiparous cows dried-off 50 d before calving were assigned randomly to 1 of 3 dietary treatments: a controlled energy, high-fiber diet [CE; 1.39 Mcal net energy for lactation (NE_L)/kg of dry matter (DM)] formulated to supply 100% of the NE_L requirement at ad libitum intake; or a higher energy diet (1.58 Mcal/kg) fed either at ad libitum (HE) or restricted (RE) intake to supply ∼150 or 80% of the NE_L requirements, respectively. After calving, all cows were fed the same lactation diet. Cows were individually fed and remained in the study until 28 d postpartum. Data were analyzed using 2 contrasts: CE versus HE (effect of diet composition in cows fed for ad libitum DM intake) and HE versus RE (effect of ad libitum or restricted intake of the same diet). Prepartum intakes of DM and NE_L as well as energy balance (EB), were greater for HE than CE and greater for HE than RE. Body weight (BW) gain was higher in HE than in RE, but CE and HE did not differ. Change in body condition score did not differ between CE and HE or HE and RE. Postpartum intakes of DM and NE_L, EB, BW, body condition score, calf birth BW, milk yield, and milk components did not differ between CE and HE or HE and RE. Concentrations of glucose, insulin, nonesterified fatty acids, β-hydroxybutyrate, Ca, and Mg pre- and postpartum did not differ among diets. Although sample size was low, dry period plane of energy intake affected prepartum DM intake, EB, and BW gain but did not affect postpartum intakes of DM and NE_L, yields of milk and milk components, or blood metabolites in healthy cows.

Berberine supplementation modulates the somatotropic axis and ameliorates glucose tolerance in dairy goats during late gestation and early lactation

BACKGROUND

Pregnancy, parturition, and the onset of lactation represent an enormous physiological and hormonal challenge to the homeostasis of dairy animals, being a risk for their health and reproduction. Thus, as a part of the homothetic changes in preparturition period, goats undergo a period of IR as well as uncoupled GH/IGF-1 axis. The objective for this study was to determine the effect of berberine (BBR) during the peripartal period on hormonal alteration and somatotropic axis in dairy goats as well as glucose and insulin kinetics during an intravenous glucose tolerance test (IVGTT). At 21 days before the expected kidding date, 24 primiparous Saanen goats were assigned randomly to 4 dietary treatments. Goats were fed a basal diet from wk. 3 antepartum (AP) until wk. 3 postpartum (PP) supplemented with 0 (CTRL), 1 (BBR1), 2 (BBR2), and 4 (BBR4) g/d BBR. Blood samples were collected on days - 21, - 14, - 7, 0, 7, 14, and 21 relative to the expected kidding date. An IVGTT was also performed on day 22 PP.

RESULTS

Compared with CTRL, supplementation with either BBR2 or BBR4 increased DMI at kidding day and PP, as well as body conditional score (BCS) and milk production (p ≤ 0.05). On d 7 and 14 PP plasma glucose was higher in BBR2- and BBR4-treated than in CTRL. The glucagon concentration was not affected by BBR during the experimental period. However, supplemental BBR indicated a tendency to decrease in cortisol concentration on days 7 (p = 0.093) and 14 (p = 0.100) PP. Lower plasma GH was observed in BBR than in non-BBR goats (p ≤ 0.05). Plasma IGF-1 concentration was enhanced in both BBR2 and BBR4 at kidding and day 7 PP (p ≤ 0.05). During the IVGTT, glucose area under the curve (AUC), clearance rate (CR), T1/2, and Tbasal was lower (p ≤ 0.05) in both BBR2 and BBR4 goats as compared with CTRL. Likewise, the insulin CR was higher (p ≤ 0.05) in goats receiving either BBR2 or BBR4 which was accompanied by a lower insulin T1/2 and AUC.

CONCLUSIONS

Altogether, our results indicated an improved glucose and insulin status along with the modulation of the somatotropic axis and glucose and insulin response to IVGTT in dairy goats supplemented with 2 and 4 g/d BBR.

Fatty Acid Profile and Enterolactone Content of Early and Commercial Milk of Dairy Cows Supplemented with Flaked Flaxseed during the Dry Period

Various supplementations in animal feeding have been investigate in order to enrich food of animal origin with n-3 fatty acids. Although the effects of flaxseeds inclusion in diets for lactating dairy have already been assessed, few studies have focused on this n-3 source supplementation during the transition period. The aim of this work was to evaluate the effects of flacked flaxseed (200 g/head/day; 2.13% DM) dietary treatment during the dry period on milk yield and quality in the 30 days after calving. In addition, the enterolactone content in plasma (before and after calving) and in milk of cows fed diets supplemented or not with flaxseed was considered. The study demonstrated that the carry-over effect on the milk profile of C18:2, C18:3 n-3, and C20:5 n-3 was significantly higher in flaxseed diet than in the control one at 4th day of lactation. A significant increase of enterolactone on milk from flaxseed fed cows was observed only at 15 sampling day. The quick modification in fatty acid (FA) profile of the milk in the first few days of lactation suggests that the carry over effect from pre-calving flaxseed feeding at this concentration was very short lasting.

Effects of starch concentration of close-up diets on rumen pH and plasma metabolite responses of dairy cows to grain challenges after calving

The objective of this study was to evaluate the effects of starch concentration of close-up diets on plasma concentrations of energy metabolites and rumen pH of dairy cows after calving. Eighteen multiparous Holstein dairy cows (mean parity = 2.78; mean body weight = 708 kg; mean body condition score = 3.08) fitted with ruminal cannulas were assigned to treatment balanced for parity, body condition score, and expected calving date. Cows were enrolled in the study at d 28 ± 3 before the expected calving date and fed either a low-starch (LS; 14.0% starch) or high-starch (HS; 26.1% starch) diet until parturition. All cows were fed a common diet after calving (25.1% starch). A grain challenge was performed on d 7 ± 2 and 21 ± 2 after calving by dosing 6.35 kg (dry matter basis) of finely ground barley and wheat grain (1:1) into the rumen via cannula. Feeding the HS diet before calving increased the duration (369 vs. 49 min/d) and area of pH below 5.8 (85.1 vs. 5.2 pH × min/d) during d -10 to -8. In addition, even though all cows were fed a common diet after calving, HS cows tended to have longer duration (177 vs. 76 min/6 h) and greater area of pH below 5.8 (67.8 vs. 20.3 pH × min/6 h) during a grain challenge on d 7. Plasma concentration of insulin tended to be greater in cows fed the HS diet (1.40 vs. 1.09 ng/mL), whereas plasma free fatty acid concentration was not different between treatments during the grain challenge on d 7. During the grain challenge on d 21, neither rumen pH nor blood metabolites were different between the HS and LS cows. These findings suggested that feeding an HS diet during the close-up period does not mitigate rumen pH depression but may exacerbate it after calving compared with feeding an LS diet.

Dietary supplementation with glucogenic precusors and fatty acids improves performance and health of periparturient dairy cows

This experiment aimed to make a comparison between the effect of a mix of two energy preparations (a glucogenic preparation (G) and a free fatty acid preparation (F)), administered in the diet during the transition period over different periods of time (5 or 8 weeks), on the animal condition, feed intake, yield and composition of milk, and blood and urine parameters. The experimental additive was a mixture (1:1) of two energy preparations, namely, a loose mixture of propylene glycol and sodium propionate and a free fatty acid preparation in the form of rumen-undegradable pellets. The study included 50 Polish Black-and-White Holstein–Friesian dairy cows, allocated into five treatment groups, including one control (C) and four experimental ones (G1F1, G2F2, G2F1 and G1F2). The preparations were mixed at a 1:1 weight ratio (500 g per head, comprising 250G and 250F) and they were administered to all experimental groups of cows daily as a component of the experimental concentrate for 5 weeks (from the 2nd week before the expected calving and until the 3rd week of lactation). From the 4th until the 6th week of lactation, the supplementation in the experimental groups changed and animals received either no additive (G1F1), or were continuously supplemented with the G–F mix (G2F2), or received only G (G2F1) or only F (G1F2). The preparations used in the study had a long-term influence on the increase in the milk yield of cows, on the improvement of their health condition, and on the reduction of weight loss. The study results confirmed that prolongation of the supplementation until the 6th week of lactation may cause favourable changes in animal performance and milk quality. Due to different modes of action, the simultaneous supplementation of G and F reduced the negative energy balance in the cow and improved milk production and composition. The best results were obtained after administration of the mixture (1:1) of the G and F at the dose of 500 g/cow.day over the 8-week periparturient period.

Effects of feeding a source of omega-3 fatty acid during the early postpartum period on the endocannabinoid system in the bovine endometrium

A total of sixteen Holstein dairy cows (35 ± 1.1 kg/d of milk yield) were randomly assigned to consider the effects of feeding omega-3 sources on endometrial endocannabinoids system (ECS) genes expression to understand the effect mechanism of omega-3 on reproductive performances during the early postpartum period to evaluate to what extent can be intervened in reproduction, e.g. via nutrition to improve fertility. Experimental diets were 1) either protected palm oil (control) or 2) extruded linseed (linseed). Cows (n = 16) were fed from calving date to 70 days in milk (DIM). There was no difference between groups (mean ± S.E.M.) in parity (3.0 ± 1.00) or body condition score (BCS) at calving day (3.1 ± 0.25). At 30 DIM, the ovulatory cycles of cows were synchronized using two injections of prostaglandin F2α (PGF2α) with a 14-day interval. On day 15 of synchronized estrous cycle (d0 = ovulation) uterine endometrial biopsies were collected to evaluate the expression of genes related to ECS (endocannabinoid receptor (CNR2), N-acyl phosphatidylethanolamine phospholipase D (NAPEPLD), fatty acid amide hydrolase (FAAH), N-acylethanolamine acid amidase (NAAA), monoglyceride lipase (MGLL)) and PGF2α. Results showed that dry matter intake and milk yield were not affected by diets. Uterine endometrial NAAA (7.69 fold), and MGLL (1.96 fold) genes expression were greater (P < 0.05) in cows fed linseed compared with control ones. The messenger RNA (mRNA) levels of CNR-2 (4.26 fold), and NAPEPLD (20.0 fold) were decreased (P < 0.05) in animals fed linseed compared to control cows. The expression of mRNA for the FAAH was not influenced by the diets. First service conception rate was greater in cows fed linseed compared to control cows (75 vs. 25%). Pregnancy loss within 32-60 day after artificial insemination (AI) was lower in cows fed linseed compared to control cows (0 vs. 100%). In conclusion these data demonstrated that positive effect of omega-3 on reproduction may act through a mechanism involving the ECS. However, more studies to be undertaken to confirm these results.

Concentrate supplementation of a diet based on medium-quality grass silage for 4 weeks prepartum: Effects on cow performance, health, metabolic status, and immune function

Because negative energy balance (EB) contributes to transition-period immune dysfunction in dairy cows, dietary management strategies should aim to minimize negative EB during this time. Prepartum diets that oversupply energy may exacerbate negative EB in early lactation, with detrimental effects on immune function. However, with lower body condition score (BCS) cows, it has been shown that offering concentrates in addition to a grass silage-based diet when confined during an 8-wk dry period resulted in increased neutrophil function in early lactation. The aim of this study was to examine if similar benefits occur when concentrate feeding was restricted to a 4-wk period prepartum. Twenty-six multiparous and 22 primiparous Holstein-Friesian cows were offered ad libitum access to medium-quality grass silage until 28 d before their predicted calving dates (actual mean of 32 d prepartum; standard deviation = 6.4). At this time multiparous cows had a mean BCS of 2.9 (standard deviation = 0.12) and primiparous cows a mean BCS of 3.0 (standard deviation = 0.14) on a 1 to 5 scale. Cows were then allocated in a balanced manner to 1 of 2 treatments (13 multiparous cows and 11 primiparous cows on each treatment): silage only (SO) or silage plus concentrates (S+C) until calving. Cows on SO were offered the same grass silage ad libitum. Cows on S+C were offered an ad libitum mixed ration of the same grass silage and additional concentrates in a 60:40 dry matter (DM) ratio, which provided a mean concentrate DM intake (DMI) of 4.5 kg/cow per d. After calving, all cows were offered a common mixed ration (grass silage and concentrates, 40:60 DM ratio) for 70 d postpartum. Offering concentrates in addition to grass silage during the 4 wk prepartum increased prepartum DMI (12.0 versus 10.1 kg/cow per d), EB (+40.0 versus +10.6 MJ/cow per d), and body weight (BW; 640 versus 628 kg), and tended to increase BCS (3.02 versus 2.97). However, postpartum DMI, milk yield, milk composition, BW change, BCS change, serum nonesterified fatty acid, and β-hydroxybutryrate concentrations, health, and corpus luteum measures were unaffected by treatment. The in vitro assays of neutrophil phagocytosis, neutrophil oxidative burst, and interferon gamma production, conducted on blood samples obtained at d 14 prepartum and d 3, 7, 14, and 21 postpartum, were unaffected by treatment. Primiparous cows had higher phagocytic fluorescence intensity at d 14 prepartum and d 3 and 7 postpartum; a higher percentage of neutrophils undergoing oxidative burst at d 3, 7, and 21 postpartum; and a higher oxidative burst fluorescence intensity at d 14 prepartum and d 7, 14, and 21 postpartum compared with multiparous cows. This suggests that neutrophil function of primiparous cows was less sensitive to the changes occurring during the transition period than that of multiparous cows. In conclusion, offering concentrates during the 4-wk period prepartum had no effect on postpartum DMI, milk yield, body tissue mobilization, EB, measures of neutrophil or lymphocyte function, health, or corpus luteum activity.

Metabolic profiles of cow's blood; a review

The term 'metabolic profile' refers to the analysis of blood biochemical parameters that are useful to assess and prevent metabolic and nutritional disorders in dairy herds. In the higher standards of milk production, the priority in modern breeding is keeping dairy cows in high lactation and healthy. The proper analysis, as well as control. of their feeding and metabolic status is immensely important for the health condition of the herd. The disproportion between the genetically determined ability for milk production and the limitations in improving the energy value of the ration may be the cause of metabolic disorders. Negative energy balance has a major impact on the body's hormonal balance and organ functions and mostly appears during transition periods: from 3 to 2 weeks prepartum until 2-3 weeks postpartum. The term 'transition' is used to underscore the important physiological, metabolic and nutritional changes occurring in this time. The manner in which these changes occur and how they are diagnosed and detected are extremely important, as they are closely related to clinical and subclinical postpartum diseases, lactation and reproductive performance - factors that significantly shape the profitability of production. Therefore the priority for intensive milk production is prevention of metabolic diseases and other disorders. It is the intent of this review to synthesize and summarize the information currently available on metabolic status and physiological changes in the cow's body that occur during lactation, as well as to discuss the interpretation of the results, which will be a useful diagnostic tool in nutritional evaluations of the dairy herd. © 2016 Society of Chemical Industry.

Milk yield, milk composition, and hepatic lipid metabolism in transition dairy cows fed flaxseed or linola

The response of transition dairy cows to dietary supplementation with fat sources of various fatty acid profiles could affect hepatic fat metabolism differently. Twenty-eight Holstein cows were blocked for similar calving date 4wk before expected parturition to compare the effects of feeding sources of n-3 and n-6 fatty acids on milk production and composition, plasma metabolites, and liver parameters. Cows within each block were assigned to 1 of 3 isonitrogenous and isoenergetic diets: control with a source of calcium salts of palm oil (MEG; 1.1 and 2.6% of the dry matter in prepartum and postpartum diets, respectively); n-3 fatty acids supplied as whole flaxseed (WFL; 4.8 and 7.7% of the dry matter in prepartum and postpartum diets, respectively); and n-6 fatty acids supplied as whole linola (WLO; 4.8 and 7.7% of the dry matter in prepartum and postpartum diets, respectively). Diets were fed until wk 14 of lactation. Contrasts of WFL versus WLO and polyunsaturated fatty acids versus MEG were compared. Cows fed polyunsaturated fatty acids increased dry matter intake over time at a greater extent than those fed MEG, which resulted in enhanced energy balance. Cows fed MEG produced more milk compared with those fed polyunsaturated fatty acids, and there was no difference between those fed WFL and WLO. We found no effect on body condition score and body weight. Plasma concentrations of glucose, fatty acids, and BHB were similar among diets. There was no effect of diet on concentration of glycogen and activities of superoxide dismutase and glutathione peroxidase in the liver. We observed higher concentrations of hepatic lipids and triacylglycerol in cows fed MEG compared with those fed polyunsaturated fatty acids, and no difference between WFL and WLO. Hepatic catalase activity tended to be higher on wk 4 after calving for cows supplemented with WFL compared with those fed WLO. Feeding linoleic and linolenic acids as unprotected oilseeds increased dry matter intake over time at a greater extent for cows fed MEG, improved the energy status, and lowered hepatic lipids and triacylglycerol contents, which may contribute to enhance the health status of transition dairy cows.

Effects of energy density in close-up diets and postpartum supplementation of extruded full-fat soybean on lactation performance and metabolic and hormonal status of dairy cows

This experiment was conducted to investigate the effect of energy density (ED) in the close-up period and supplementation of extruded full-fat soybean (ESB) during the first 4 wk after parturition on intake, body weight (BW), metabolic status, and performance of dairy cows. Fifty-seven Chinese Holstein cows with similar parity, previous 305-d milk yield, and expected calving date were dried off at -60 d relative to parturition and fed the standard herd dry-cow diet until -21 d relative to parturition. Energy density at low (LED, 1.25 Mcal/kg), medium (MED, 1.41 Mcal/kg) or high (HED, 1.55 Mcal/kg) levels of the close-up diets and postpartum supplementation of ESB at 0 kg/d (control, CON) or 1.5 kg/d (TRT) were used in a 3 × 2 factorial arrangement. All cows received the same CON diet from wk 5 to wk 8. As ED increased in the close-up diet, cows had higher dry matter intake and gained more BW and body condition score, and consequently were in improved energy balance status during the prepartum period, but lost more BW and more body condition score during the first 8 wk of lactation. Compared with LED cows, HED cows had higher blood concentrations of insulin and glucose, and lower nonesterified fatty acids (NEFA) prepartum, but had lower insulin concentration, higher leptin concentration and tended to have higher NEFA concentration postpartum. Milk production was not affected by the prepartum ED, although HED cows produced approximately 2 kg/d less milk than MED and LED cows during early lactation. Postpartum ESB supplementation elevated blood glucagon concentration regardless of prepartum ED during the first 4 wk of lactation. Interactive effects between prepartum ED and postpartum ESB supplementation were observed in blood concentrations of insulin, NEFA, bilirubin, total protein, albumin, and globulin. During early lactation, TRT decreased globulin concentrations in MED cows, and reduced NEFA and bilirubin concentrations in HED cows. Compared with CON, TRT cows had higher yields of milk (34.32 vs. 36.53 kg/d), milk lactose (1.63 vs. 1.74 kg/d), and solids-nonfat (2.98 vs. 3.18 kg/d), tended to have a greater yield of milk protein (1.11 vs. 1.17 kg/d), but tended to have lower milk fat percentage (4.18 vs. 3.94%) during the first 4 wk of lactation. In conclusion, compared with feeding the HED diet, feeding the LED diet during the close-up dry period had positive carryover effects on metabolism and production during early lactation, and the MED diet showed no advantage over the LED diet. Extruded full-fat soybean supplementation during the first 4 wk of lactation had positive effects on postpartum metabolic status, especially for those receiving the MED or HED diet prepartum, and resulted in an overall improved milk production during early lactation.

Effects of prepartum fat supplementation on plasma concentrations of glucagon-like peptide-1, peptide YY, adropin, insulin, and leptin in periparturient dairy cows

Dietary fat supplementation during the periparturient period is one strategy to increase energy intake and attenuate the degree of negative energy balance during early lactation; however, little is known of the underlying hormonal and metabolic adaptations. We evaluated the effects of prepartum fat supplementation on energy-balance parameters and plasma concentrations of glucagon-like peptide-1, peptide tyrosine-tyrosine (PYY), adropin, insulin, leptin, glucose, nonesterified fatty acid, and β-hydroxybutyric acid in dairy cows. Twenty-four pregnant dairy cows were randomized to diets containing either rolled canola or sunflower seed at 8% of dry matter, or no oilseed supplementation, during the last 5 wk of gestation and then assigned to a common lactation diet postpartum. Blood samples were collected at -2, +2, and +14 h relative to feeding, at 2 wk after the initiation of the diets, and at 2 wk postpartum. Dietary canola and sunflower supplementation alone did not affect energy balance, body weight, and plasma concentrations of glucagon-like peptide-1, PYY, adropin, insulin, leptin, nonesterified fatty acid, and β-hydroxybutyric acid; however, canola decreased and sunflower tended to decrease dry matter intake. We also observed that the physiological stage had a significant, but divergent, effect on circulating hormones and metabolite concentrations. Plasma glucagon-like peptide-1, PYY, adropin, nonesterified fatty acid, and β-hydroxybutyric acid concentrations were greater postpartum than prepartum, whereas glucose, insulin, leptin, body weight, and energy balance were greater prepartum than postpartum. Furthermore, the interaction of treatment and stage was significant for leptin and adropin, and tended toward significance for PYY and insulin; only insulin exhibited an apparent postprandial increase. Postpartum PYY concentrations exhibited a strong negative correlation with body weight, suggesting that PYY may be associated with body weight regulation during the transition period. These novel findings demonstrate that the transition from pregnancy to lactation is a stronger determinant of circulating gut hormone concentrations than dietary lipid in transition dairy cows.

Supplementation of herbal plants differently modulated metabolic profile, insulin sensitivity, and oxidative stress in transition dairy cows fed various extruded oil seeds

The study investigated the effects of a mixture of herbal plants (HM) and two sources of unsaturated fatty acids (FA), extruded linseed (LS) and soybean (SB), on metabolic profile, insulin sensitivity, and oxidative status of transition dairy cows. Thirty-two prepartum Holstein cows, blocked by parity and calving day, were randomly assigned to 1 of 4 treatments, in a 2×2 factorial design, starting from 25 days before the expected calving date to 26 days postpartum. The supplementation rates of HM were 150 and 170 g/animal/day at pre- and postpartum, respectively. Blood samples were analyzed for metabolites on day 7.15±1.70 prepartum and on days 1 and 21 postpartum. An intravenous glucose tolerance test (IV-GTT) was conducted on day 25 postpartum. Data showed that cows supplemented with HM had lower serum concentration of NEFA (0.395 vs. 0.602±0.044 mmol/L; P<0.01) and NEFA to insulin ratio (P<0.01) postpartum. Compared to animals fed SB-based diets, cows fed the LS-based diet had greater serum glucose concentration during prepartum (80.7 vs. 71.3±3.32 mg/dL; P=0.06) and postpartum period (86.3 vs. 73.5±3.35 mg/dL; P=0.01), as well as lower NEFA (0.425 vs. 0.572±0.044 mmol/L; P=0.03) and insulin to glucose ratio (P<0.01) postpartum. Revised quantitative insulin-sensitivity check index revealed that supplementing HM in LS-based diet improved insulin sensitivity (0.45 vs. 0.41±0.013; P=0.03) prepartum, whereas after parturition, the HM addition was effective for both oil seeds (0.40 vs. 0.37±0.008; P=0.06) in enhancing insulin sensitivity. Result of IV-GTT indicated that cows fed LS-based diets had higher basal glucose concentration (63.7 vs. 55.7±2.37; mg/dL; P=0.02) and lower glucose area under the curve (995.8 vs. 1529.5±100.7; mg/dL×45 min; P<0.01). Supplementing HM resulted in greater total antioxidant capacity prepartum (0.55 vs. 0.48±0.017 nmol/L; P=0.01) and lower malondialdehyde concentration at prepartum (1.03 vs. 1.96±0.140 μmol/L; P<0.01) and postpartum (1.32 vs. 1.88±0.178 μmol/L; P=0.04). Although feeding LS ameliorated insulin resistance, this feeding strategy lowered total antioxidant capacity prepartum (0. 48 vs. 0.55±0.017 nmol/L; P<0.01) and increased malondialdehyde concentration postpartum more than the SB diet (1.91 vs. 1.28±0.172 μmol/L; P=0.02). Overall, both HM supplementation and LS feeding improved metabolic profile and insulin response following glucose infusion, although feeding of LS-based diets induced an increased oxidative stress.

Effect of crude degummed canola oil and ad libitum grazing on plasma metabolites of primiparous Holstein-Friesian cows in a pasture-based system

Background

The supplementation of fat to lactating dairy cows has long been used as a management tool to increase dietary energy density for improving cow production, reproduction and to alleviate negative energy balance. Attempts have been made to investigate the effect of canola meal on plasma metabolites in lactating cows, but the results have been diverse and inconsistent. To our current knowledge, there is a dearth of published information on the utilization of Crude Degummed Canola Oil (CDCO) in pasture-based dairy systems. Therefore, the objective of this study was to investigate the changes in plasma metabolite profiles of pasture-based, primiparous, Holstein-Friesian cows supplemented with varying dietary levels of CDCO for eight weeks. The study tested the hypothesis that feeding grazing primiparous Holstein-Friesian cows for eight weeks with incremental levels of CDCO supplement will decrease plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA), but increase plasma cholesterol and glucose metabolites.

Results

Twenty lactating primiparous Holstein-Friesian cows 40 days in milk were randomly allotted into four treatment groups that consisted of a wheat-based, pelleted basal diet with no supplemental CDCO (control), basal diet with CDCO added at 25 ml/kgDM (DM; dry matter) (low), 35 ml/kgDM (medium) and 50 ml/kgDM (high) in an eight-week feeding trial, after two weeks of adjustment. Treatment influenced BHBA but had no effect on plasma NEFA, cholesterol and glucose metabolite profiles (P > 0.05). However, week of supplementation had a significant effect (P < 0.05) on BHBA, NEFA and glucose concentrations.

Conclusions

We concluded that with the exception of BHBA, CDCO at current levels of supplementation does not alter the plasma metabolite profiles of grazing primiparous cows. The lack of significant differences across treatments seems to indicate that higher levels of CDCO than the current levels used in this study, are probably needed. Furthermore, the duration of supplementation with CDCO had a greater impact on plasma metabolites than the levels of supplementation. Our findings also suggest that primiparous cows grazing high quality pastures during spring have sufficient energy intakes to prevent negative energy balance at 40 days in milk without the need for added fat supplements.

Effects of dietary crude glycerin supplementation on nutrient digestibility, ruminal fermentation, blood metabolites, and nitrogen balance of goats

This experiment was conducted to evaluate the effects of increasing concentrations of crude glycerin (CGLY) in diets on nutrient utilization, ruminal fermentation characteristics, and nitrogen utilization of goats. Four male crossbred (Thai Native×Anglo Nubian) goats, with an average initial weight of 26±3.0 kg, were randomly assigned according to a 4×4 Latin square design with four 21 days consecutive periods. Treatments diets contained 0%, 5%, 10%, and 20% of dietary DM of CGLY. Based on this experiment, there were no significant differences (p>0.05) among treatment groups regarding DM intake and digestion coefficients of nutrients (DM, OM, CP, EE, NDF, and ADF). Likewise, mean serum glucose, BHBA, and PCV concentrations were not affected (p>0.05) by dietary treatments, whereas serum insulin concentration linearly increased (L, p = 0.002) with increasing the amount of CGLY supplementation. Ruminal pH, NH₃-N, and BUN concentration were unchanged by dietary treatments, except for 20% of CGLY, NH₃-N, and BUN were lower (p<0.05) than for the diets 10% of CGLY, while the difference between the diets 0%, 5%, and 20% of CGLY were not significant. The amount of N absorption and retention were similar among treatments. Based on this study, CGLY levels up to 20% in total mixed ration could be efficiently utilized for goats and this study elucidates a good approach to exploiting the use of biodiesel production for goat production.

A comparison of the concentrations of energy-balance-related variables in jugular and mammary vein blood of dairy cows with different milk yield

The aim of this study was to compare the concentrations of blood variables obtained simultaneously from the jugular and mammary veins of dairy cows. Eighty Holstein cows were divided into four equal groups: dry, low- (LY), medium- (MY) and high-yielding (HY). Blood insulin, glucose, non-esterified fatty acid (NEFA), beta-hydroxybutyrate (BHBA) and urea concentrations were measured. The jugular and mammary vein (J/M) ratio between concentrations of each variable was calculated. Differences between the groups of cows in concentrations of variables in the jugular vein were not in accordance with those obtained for the mammary vein. J/M values for insulin and glucose concentrations were above 1.0 in all groups of cows. The ratios for NEFA and BHBA concentrations were under or equal to 1.0 in dry and LY cows but above 1.0 in the MY and HY groups, indicating that in MY and HY cows those metabolites are apparently utilised by the mammary gland. J/M values for urea were above 1.0 in dry and LY cows but less than 1.0 in groups MY and HY, indicating that in the latter case urea is apparently released by the mammary gland. In conclusion, J/M for NEFA, BHBA and urea may be useful for estimation of the critical point when the mammary gland receives insufficient energy precursors for its current activity.