Y. Ying

Effect of a high-palmitic acid fat supplement on milk production and apparent total-tract digestibility in high- and low-milk yield dairy cows

The effect of a high-palmitic acid fat supplement was tested in 12 high-producing (mean = 42.1 kg/d) and 12 low-producing (mean = 28.9 kg/d) cows arranged in a replicated 3 × 3 Latin square design. Experimental periods were 21 d, with 18d of diet adaptation and 3 d of sample collection. Treatments were (1) control (no supplemental fat), (2) high-palmitic acid (PA) supplement (84% C16:0), and (3) Ca salts of palm fatty acid (FA) supplement (Ca-FA). The PA supplement had no effect on milk production, but decreased dry matter intake by 7 and 9% relative to the control in high- and low-producing cows, respectively, and increased feed efficiency by 8.5% in high-producing cows compared with the control. Milk fat concentration and yield were not affected by PA relative to the control in high- or low-producing cows, although PA increased the yield of milk 16-C FA by more than 85 g/d relative to the control. The Ca-FA decreased milk fat concentration compared with PA in high-, but not in low-producing cows. In agreement, Ca-FA dramatically increased milk fat concentration of trans-10 C18:1 and trans-10, cis-12 conjugated linoleic acid (>300%) compared with PA in high-producing cows, but not in low-producing cows. No effect of treatment on milk protein concentration or yield was detected. The PA supplement also increased 16-C FA apparent digestibility by over 10% and increased total FA digestibility compared with the control in high- and low-producing cows. During short-term feeding, palmitic acid supplementation did not increase milk or milk fat yield; however, it was efficiently absorbed, increased feed efficiency, and increased milk 16-C FA yield, while minimizing alterations in ruminal biohydrogenation commonly observed for other unsaturated fat supplements. Longer-term experiments will be necessary to determine the effects on energy balance and changes in body reserves.

The daily rhythm of milk synthesis is dependent on the timing of feed intake in dairy cows

Regulation of the daily rhythm of milk synthesis is important to production animals and breastfeeding, but is difficult to observe in nursing animals. The rate of food intake varies over the day and is expected to create a daily rhythm of nutrient absorption. The objective of this study was to determine if the timing of food intake entrains a daily pattern of milk synthesis. Seventeen Holstein cows were used in a crossover design. Treatments were ad libitum feeding of a total mixed ration once daily (1× fed) or fed in four equal meals every 6 h (4× fed). Cows were milked every 6 h the last 7 days of each period. There was a treatment by time of day interaction for milk and milk component yield and concentration. Milk fat and protein concentration and yield exhibited a daily rhythm and the amplitude of the rhythm was reduced in 4× fed. In addition, milk fat percent was higher in 4× fed than 1× fed at three of the four milking intervals (0.22–0.45% higher) and 4× fed increased daily milk fat yield. Treatment by time of day interactions were detected for plasma glucose, insulin, and blood urea nitrogen. These variables also fit a cosine function with a 24 h period and the amplitudes of plasma glucose, insulin, and blood urea nitrogen rhythms were decreased by 4× feeding. In conclusion, there is a circadian pattern of milk synthesis in the dairy cow that is responsive to the timing of food intake.

The effects of feeding time on milk production, total-tract digestibility, and daily rhythms of feeding behavior and plasma metabolites and hormones in dairy cows

The timing of feed intake entrains circadian rhythms regulated by internal clocks in many mammals. The objective of this study was to determine if the timing of feeding entrains daily rhythms in dairy cows. Nine Holstein cows were used in a replicated 3 × 3 Latin square design with 14-d periods. An automated system recorded the timing of feed intake over the last 7 d of each period. Treatments were feeding 1×/d at 0830 h (AM) or 2030 h (PM) and feeding 2×/d in equal amounts at 0830 and 2030 h. All treatments were fed at 110% of daily intake. Cows were milked 2×/d at 0500 and 1700 h. Milk yield and composition were not changed by treatment. Daily intake did not differ, but twice-daily feeding tended to decrease total-tract digestibility of organic matter and neutral detergent fiber (NDF). A treatment by time of day interaction was observed for feeding behavior. The amount of feed consumed in the first 2h after feeding was 70% greater for PM compared with AM feeding. A low rate of intake overnight (2400 to 0500 h; 2.2 ± 0.74% daily intake/h, mean ± SD) and a moderate rate of intake in the afternoon (1200 to 1700 h; 4.8 ± 1.1% daily intake/h) was noted for all treatments, although PM slightly reduced the rate during the afternoon period compared with AM. A treatment by time of day interaction was seen for fecal NDF and indigestible NDF (iNDF) concentration, blood urea nitrogen, plasma glucose and insulin concentrations, body temperature, and lying behavior. Specifically, insulin increased and glucose decreased more after evening feeding than after morning feeding. A cosine function within a 24-h period was used to characterize daily rhythms using a random regression. Rate of feed intake during spontaneous feeding, fecal NDF and iNDF concentration, plasma glucose, insulin, NEFA, body temperature, and lying behavior fit a cosine function within a 24-h period that was modified by treatment. In conclusion, feeding time can reset the daily rhythms of feeding and lying behavior, core body temperature, fecal NDF and iNDF concentration, and plasma blood urea nitrogen, glucose, and insulin concentration of dairy cows, but has no effect on daily DMI and milk production.

The effect of rumen digesta inoculation on the time course of recovery from classical diet-induced milk fat depression in dairy cows

Ten ruminally cannulated cows were used in a crossover design that investigated the effect of rumen digesta inoculation from non-milk fat-depressed cows on recovery from classical diet-induced milk fat depression (MFD) characterized by reduced fat yield, reduced de novo milk fat synthesis, and increased alternate trans isomers. Two additional cows fed a high-fiber and low-polyunsaturated fatty acid (FA) diet (31.8% neutral detergent fiber, 4.2% FA, and 1.2% C18:2) were used as rumen digesta donors. Milk fat depression was induced during the first 10d of each period by feeding a low-fiber and high-polyunsaturated FA diet (induction; 26.1% neutral detergent fiber, 5.8% FA, and 1.9% C18:2), resulting in a 30% decrease in milk fat yield. A recovery phase followed where all cows were switched to the high-forage, low-polyunsaturated FA diet and were allocated to (1) control (no inoculation) or (2) ruminal inoculation with donor cow digesta (8 kg/d for 6d). Milk yield and composition were measured every 3d. Milk yield progressively decreased during recovery. Milk fat concentration increased progressively during the recovery phase and no effect of treatment existed at any time point. Also, no treatment effect of milk fat yield was detected. The concentration of milk de novo FA increased progressively during recovery for both treatments and was higher for inoculated compared with control cows on d 6. In agreement, milk fat concentration of trans-10,cis-12 conjugated linoleic acid decreased progressively in both treatments and was lower in inoculated cows on d 3 and 6. Ruminal inoculation from non-milk fat-depressed cows did not change milk fat yield, but slightly accelerated the rate of recovery of de novo FA synthesis and normal ruminal FA biohydrogenation, demonstrating a possible opportunity for other interventions that improve the ruminal environment to accelerate recovery from this condition.

Comparison of enriched palmitic acid and calcium salts of palm fatty acids distillate fat supplements on milk production and metabolic profiles of high-producing dairy cows

A variable response to fat supplementation has been reported in dairy cows, which may be due to cow production level, environmental conditions, or diet characteristics. In the present experiment, the effect of a high palmitic acid supplement was investigated relative to a conventional Ca salts of palm fatty acids (Ca-FA) supplement in 16 high-producing Holstein cows (46.6±12.4kg of milk/d) arranged in a crossover design with 14-d periods. The experiment was conducted in a non-heat-stress season with 29.5% neutral detergent fiber diets. Treatments were (1) high palmitic acid (PA) supplement fed as free FA [1.9% of dry matter (DM); 84.8% C16:0] and (2) Ca-FA supplement (2.3% of DM; 47.7% C16:0, 35.9% C18:1, and 8.4% C18:2). The PA supplement tended to increase DM intake, and increased the yields of milk and energy-corrected milk. Additionally, PA increased the yields of milk fat, protein, and lactose, whereas milk concentrations of these components were not affected. The yields of milk de novo and 16-C FA were increased by PA compared with Ca-FA (7 and 20%, respectively), whereas the yield of preformed FA was higher in Ca-FA. A reduction in milk fat concentration of de novo and 16-C FA and a marginal elevation in trans-10 C18:1 in Ca-FA is indicative of altered ruminal biohydrogenation and increased risk of milk fat depression. No effect of treatment on plasma insulin was observed. A treatment by time interaction was detected for plasma nonesterified fatty acids (NEFA), which tended to be higher in Ca-FA than in PA before feeding. Overall, the palmitic acid supplement improved production performance in high-producing cows while posing a lower risk for milk fat depression compared with a supplement higher in unsaturated FA.

The effects of feeding rations that differ in fiber and fermentable starch within a day on milk production and the daily rhythm of feed intake and plasma hormones and metabolites in dairy cows

A daily pattern of feed intake, milk synthesis, and plasma metabolites and hormones occurs in dairy cows fed a total mixed ration once or twice a day. The objective of this study was to determine if feeding multiple rations within a day, complementing these rhythms, would improve milk production. Twelve Holstein cows were used in a replicated 3×3 Latin square design with 21-d periods. Cows were housed in tie stalls with feed tubs, and feed weight was recorded every 10 s for observation of feeding behavior. Rations were a low fiber and high fermentable starch ration [LFHS; 27.4% neutral detergent fiber (NDF) and 31.7% starch based on 55.7% corn silage and 14.1% steam-flaked corn], a high fiber and low fermentable starch ration (HFLS; 31.7% NDF and 22.3% starch based on 44% corn silage, 26.3% alfalfa haylage, and no steam-flaked corn), and a total mixed ration that was a 1:3 ratio of LFHS and HFLS (30.7% NDF, 24.5% starch). The control treatment (CON) cows were fed the total mixed ration at 0700h, the high/low treatment (HL) fed HFLS ration at 0700h and LFHS ration at 2200h, and the low/high (LH) treatment fed LFHS ration at 0700h and HFLS ration at 1100h (LFHS and HFLS rations fed at a 1:3 ratio). No effect was found of treatment on daily milk, but LH decreased milk fat concentration and yield compared with HL (0.2 percentage units and 0.24kg, respectively). Daily dry matter and NDF intake and total-tract digestibility did not differ between treatments. The HL treatment reduced intake at the morning-conditioned meal after feeding and reduced intake before the evening feeding. A treatment by time of day interaction was found for fecal NDF and indigestible NDF concentration, blood urea nitrogen (BUN), plasma insulin, and fatty acid concentration, and body temperature. The CON and LH treatments increased the daily amplitude of fecal NDF by 1.0 and 1.1 percentage units compared with HL. Plasma insulin was higher in HL than CON at 0100 and 0400h, but lower at 1300 and 1900h. Plasma fatty acids were higher for CON than HL at 0700h and HL was lower than LH at 0400 and 1900h. Plasma BUN was higher for HL than control at 0100h, but lower at 1000h. Body temperature in CON and HL treatments followed a similar diurnal pattern, whereas body temperature for LH was lower than that of HL treatment at 1300 and 2300h. No daily rhythm was found of fecal indigestible NDF concentration, plasma glucose, or fatty acids detected in the HL treatment, and the amplitude of plasma insulin and BUN was lower for HL compared with CON (70 and 60% decrease, respectively). In conclusion, feeding 2 rations that differ in fiber and fermentable starch modifies diurnal rhythms in dairy cows. Furthermore, feeding a high fiber and low fermentable starch ration during the high intake period of the day may stabilize nutrient absorption across the day.

The effects of feeding rations that differ in neutral detergent fiber and starch concentration within a day on rumen digesta nutrient concentration, pH, and fermentation products in dairy cows

There is a daily pattern of feed intake in the dairy cow, and feeding a single total mixed ration results in variation in the amount of fermentable substrate entering the rumen over the day. The object of this study was to determine if feeding multiple rations over the day that complement the pattern of feed intake would stabilize rumen pool sizes and fermentation. Nine ruminally cannulated cows were used in a 3×3 Latin square design with 23-d periods. Diets were a control diet [33.3% neutral detergent fiber (NDF)], a low-fiber diet (LF; 29.6% NDF), and a high-fiber diet (HF; 34.8% NDF). The LF and HF diets were balanced to provide the same nutrient composition as the control diet when cows were fed 3 parts of LF and 7 parts of HF. Cows on the control treatment (CON) were fed at 0900h, cows on the high/low treatment (H/L) were fed HF at 70% of daily offering at 0900h and LF at 30% of daily offering at 2200h, and cows on the low/high (L/H) treatment were fed LF at 30% of daily offering at 0900h and HF at 70% of daily offering at 1300h. All treatments were fed at 110% of daily intake. Preplanned contrasts compared CON with H/L and H/L with L/H. Feeding the LF diet in the evening resulted in a large increase in the amount of feed consumed immediately after feed delivery at that feeding. Rumen digesta starch concentration increased and NDF concentration decreased following feeding of the LF diet in both the L/H and H/L treatments. Starch pool size also increased following feeding of the LF diet in the evening and tended to increase after feeding the LF diet in the morning. Rumen ammonia concentration was increased following feeding of the HF diet in the morning and the LF diet in the evening in the H/L treatment. Additionally, cis-9 C18:1 and cis-9,cis-12 18:2 are higher in concentrate feeds and were increased after feeding the LF diet in both treatments. Trans fatty acid isomers of the normal and alternate biohydrogenation pathways followed a daily pattern, and the H/L treatment increased isomers of the alternate pathway during the overnight period following the evening feeding of the LF diet. Additionally, C17:0 decreased during the overnight period in the H/L treatment. Feeding multiple rations over the day changed feeding behavior, and the combined effect of diet composition and feeding pattern resulted in a change in rumen nutrient pool sizes and fermentation products. Feeding the low-fiber diet in the evening resulted in a large increase in feed intake after feed delivery and did not increase starch intake during the overnight period. The H/L treatment failed to stabilize rumen fermentation because of the shift in the feeding pattern. Feeding strategies that feed multiple diets over the day must integrate diet composition and feeding behavior to achieve the desired effect on rumen nutrient pools and fermentation.

The effects of feeding rations that differ in neutral detergent fiber and starch concentration within a day on production, feeding behavior, total-tract digestibility, and plasma metabolites and hormones in dairy cows

Dairy cows exhibit a daily pattern of feed intake and milk synthesis, and feeding a single total mixed ration over the day may not synchronize ruminal fermentation, nutrient absorption, and milk synthesis. Our hypothesis was that feeding a high-fiber diet during the high-intake period of the day and a low-fiber diet during the low-intake overnight period would stabilize rumen fermentation, nutrient absorption, and the availability of nutrients for milk synthesis. Nine ruminally cannulated cows were used in a 3×3 Latin square design with 23-d periods. Diets were a control [CON; 33.3% neutral detergent fiber (NDF)], a low-fiber diet (LF; 29.6% NDF), and a high-fiber diet (HF; 34.8% NDF). The HF and LF diets were balanced to provide the same nutrient composition as the control diet when cows were fed a 7:3 ratio of HF:LF. Control cows were fed once daily at 0900h. Cows in the high/low treatment (H/L) were fed HF at 70% of daily offering at 0900h and LF at 30% of daily offering at 2200h; cows in the low/high (L/H) treatment were fed LF at 30% of daily offering at 0900h and HF at 70% of daily offering at 1300h. Dry matter intake was decreased 1.9kg/d by H/L compared with CON, but intake did not differ between H/L and L/H. The H/L and L/H treatments resulted in a large amount of feed consumed after each feeding, which shifted the daily patterns of starch and fiber intake. Treatments did not differ in total-tract digestibility. We detected no differences between CON and H/L for milk yield and composition. The H/L treatment unexpectedly tended to reduce milk and reduced milk fat yield compared with L/H, although L/H was expected to result in poorer rumen fermentation and decreased milk fat yield. Treatment did not affect milk fat concentrations of trans-10 C18:1, trans-11 C18:1, or de novo synthesized fatty acids, but H/L increased milk fat concentration of preformed fatty acids compared with CON (39.15 vs. 37.38% of FA, respectively). Treatment had no effect on plasma insulin or glucose at individual time points but did modify the phase and amplitude of the daily rhythms. Daily average plasma nonesterified fatty acids (NEFA) were decreased by H/L compared with CON and L/H, and H/L treatments decreased the amplitude of the daily rhythm of NEFA by 3.4 and 6.7μEq/L compared with CON and L/H, respectively. The amplitude of the daily rhythm of plasma blood urea N was increased by more than 15% by H/L compared with CON and L/H. Feeding multiple rations over the day changed the daily pattern of starch and fiber intake and decreased daily intake without decreasing milk yield or body weight gain over the 23-d observation periods. Feeding a high-fiber diet during the high-intake period of the day and a low-fiber diet during the low-intake overnight period failed to show other benefits, likely because of the change in feeding behavior.

The effect of conjugated linoleic acid, acetate, and their interaction on adipose tissue lipid metabolism in nonlactating cows

During biohydrogenation-induced milk fat depression, adipose tissue lipogenesis may be increased through nutrients spared from milk fat synthesis. However, the direct effect of trans-10,cis-12 conjugated linoleic acid (CLA) and the indirect effect of spared nutrients on adipose tissue lipogenesis during milk fat depression is not clear. The objective of this study was to determine the direct effect of CLA, spared acetate, and their interaction on adipose tissue lipogenesis using nonlactating dairy cows as an experimental model, which allows separation of the effect of CLA and nutrient sparing. Eight ruminally cannulated, multiparous nonlactating and pregnant Holstein cows were randomly assigned to treatments in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Factors were CLA and acetate, and treatments were control (CON), rumen acetate infusions (Ac; continuous infusion of 7 mol/d adjusted to pH 6.1 with sodium hydroxide), abomasal infusion of trans-10,cis-12 CLA (CLA; 10 g/d of both trans-10,cis-12 CLA and cis-9,trans-11 CLA), and Ac + CLA (Ac + CLA). Dry matter intake was not affected by Ac, but tended to decrease by CLA. Plasma trans-10,cis-12 CLA concentration as a percentage of fatty acids was increased by 0.3 percentage points by CLA. No treatment effect was observed on plasma glucose and β-hydroxybutyrate, but an interaction was observed of CLA and Ac on plasma insulin and nonesterified fatty acids. Insulin was increased 24% by CLA, but not by Ac + CLA, and nonesterified fatty acids were increased 55% by Ac + CLA, but not by CLA alone. Lipogenesis and oxidation capacity of adipose tissue explants were not affected by treatments. Adipose expression of key lipogenic factors (peroxisome proliferator-activated receptor γ2 and sterol response element binding protein 1c) were reduced by CLA, by the interaction of Ac and CLA (sterol response element binding protein 1c), and tended to be reduced with Ac (S14 and peroxisome proliferator-activated receptor γ1). Expression of several adipose lipogenic enzymes (fatty acid synthase, acetyl-CoA carboxylase, and stearoyl-CoA desaturase 1) was reduced by CLA and Ac. An interaction was observed of Ac and CLA for fatty acid binding protein 4, which was decreased by Ac, but not Ac + CLA. In conclusion, in the nonlactating cow, adipose tissue is sensitive to the anti-lipogenic effects of trans-10,cis-12 CLA at the transcription level and acetate does not stimulate lipogenesis.

Short communication: Effect of a citrus extract in lactating dairy cows

Dry matter intake is a main driver of energy balance in lactating dairy cows, and some plant extracts have been commercially fed to dairy cows to stimulate feed intake. Citrus extracts contain several bioactive components and have been shown to modify metabolism in other animal models. Our hypothesis was that a citrus extract would increase dry matter intake. Two experiments were conducted to determine the effect of a citrus extract on intake and milk production in lactating dairy cows. In experiment one, 11 early-lactation dairy cows (experiment 1; 77 ± 15 d in milk, mean ± standard deviation) were used in a switchback design, and in experiment two, 15 mid-lactation Holstein cows (experiment 2; 157 ± 44 d in milk, mean ± standard deviation) were used in a crossover design. In both experiments, treatments were control (no supplement) or a citrus extract (4 g/d in experiment 1 and 4.5 g/d in experiment 2). Treatment periods were 21 and 14 d in experiment 1 and experiment 2, respectively, with the final 7 d used for sample and data collection. No effect was observed for treatment on dry matter intake, feeding behavior, milk yield, milk fat yield, milk protein yield, or milk composition in either experiment. Treatment also had no effect on milk trans fatty acid profile, but the extract increased total 16 carbon fatty acids 0.9 and 0.6 percentage points in experiment 1 and experiment 2, respectively. Plasma nonesterified fatty acids were decreased 6 h after feeding in both experiments (11.1 and 16.0 μEq/L in experiment 1 and experiment 2, respectively). Plasma insulin was increased 1 h before feeding compared with the control in experiment 1 (3.36 vs. 2.13 µIU/mL) and tended to increase 1.79 units 1 h before feeding in experiment 2. The citrus extract had no effect on feed intake or milk production at the dose investigated, but changed plasma insulin and nonesterified fatty acids, indicating some metabolic effects requiring further investigation.