Milk Energy Output Research Articles

Effect of reduced dietary protein level on energy metabolism, sow body composition and metabolites in plasma, milk and urine from gestating and lactating organic sows during temperate winter conditions

Energy spent on thermoregulation and the opportunity for increased locomotive activity increases the energy requirements of outdoor relative to indoor housed sows, whilst their protein requirement most likely is comparable on a daily basis. The purpose of this study was to quantify the energy needed for maintenance, maternal retention, milk production, thermoregulation and increased locomotive activity in organic sows.A total of 47 gilts (Landrace x Yorkshire; 190 kg at insemination) were reared outdoor under organic conditions for five months during winter. To study dietary effects of protein, gilts were fed one of two iso-energetic compound feeds, where dietary protein differed by 12%. Gilts had ad libitum access to grass clover silage and were fed similar amounts of metabolisable energy (ME) from compound feed equivalent to the energy recommendations for indoor sows + 15% in both groups.Collection of plasma and urine was performed on d60 and d100 of gestation and plasma, urine and milk was collected on d5, d20 and d40 of lactation. On all collection days, sows and piglets (n=635) were weighed individually, sows were back fat scanned and heartrate and locomotive activity was registered with a tracking system. Sow body composition was estimated using the deuterium dilution technique.Live weight and back fat thickness were not affected by the dietary protein level, neither was the number of total born, still born, piglet birth weight or piglet weight gain until weaning at seven weeks (14.5 kg).There was no effect of protein level on locomotive activity. Milk yield peaked with 12.9 kg/d around d20. In total, 58% of the gross energy intake was associated with milk production at d20 including heat. Milk energy output was 69 MJ ME/d at peak lactation at d20. Sows fed the low protein compound feed had a lower milk yield from d20 to d40 as compared with control fed sows (8.0 vs.10.3 kg/d; P<0.05).In conclusion, the daily feed intake was clearly insufficient in early lactation, and sows lost > 1 kg of body fat/d from d5-d20. The daily protein- and amino acid requirements were met during pregnancy, also when sows were fed the low protein compound feed, but the low protein diet supplied insufficient standardised ileal digestible lysine during lactation and this compromised the milk production. The total energy requirement of high yielding first parity outdoor sows during a mild winter was found to be ~ 68 MJ ME/d in gestation and ~153 MJ ME/d at peak lactation.

Comparative Study of Intake, Apparent Digestibility and Energy and Nitrogen Uses in Sahelian and Majorera Dairy Goats Fed Hay of Vigna unguiculata.

Simple SummaryA specialized dairy goat like the Majorera (M) breed could be a good opportunity to meet the high demand for dairy products in Senegal. The efficiency of forage use from the M breed was therefore compared to that of the local Sahelian (S) breed. To this end, 6 M and 6 S goats were given a hay of a legume, Vigna unguiculata, as sole source of nutrient and their energy and nitrogen metabolism were studied. Forage intake was higher in the M goats but also their milk production. The efficiency with which energy and nitrogen was used was similar between the two breeds but M required more energy to meet its survival needs (energy for maintenance) and possibly less protein. Thus, it appears that M is probably better suited to dairy production systems requiring more attention from breeders.This study aimed to compare digestive and metabolic characteristics in Sahelian (S) and Majorera (M) goat breeds. Six lactating females from each breed, with an average weight 27.0 ± 1.93 and 23.7 ± 1.27 kg, respectively, were used. Cowpea hay, variety 58/74, was offered as sole feed ingredient, at a rate of 2 kg of fresh matter per animal per day. The animals were placed in metabolic cages and a digestibility test was conducted according to an adaptation period of 15 days and a collection period of 7 days. The daily chemical components offered and refused and recovered faeces, urine and milk were measured in order to assess energy and nitrogen utilization. The M and S goats had similar levels of dry matter (DM) intake as well as nutrient digestibility. On a metabolic weight basis, dry matter intake, gross energy intake, metabolizable and energy intake, digestible energy and energy lost as methane production were significantly higher (p < 0.01) in M than in S goats. Urinary energy excretion was similar (p = 0.9) between breeds, while faecal energy output was higher in M than in S goats. The milk energy output from the M goats was higher than that the S goats (p < 0.05). However, metabolizable to net energy conversion efficiency (klm) was not affected by breed (p = 0.37), while N intake, milk N yield and faecal N losses, relative to metabolic weight, were significantly higher (p < 0.05) in M than in S goats. Similarly, the percentage of dietary N intake excreted in urine (UNIN) was higher in S than in M breeds. The breed factor had no effect on N retained, N digestibility, urinary N and N use efficiency. In conclusion, the M and S goats were similar in terms of energy and nitrogen use efficiency, despite higher daily milk production and DM consumption in the M goat. This suggests that the M breed is possibly more dependent on a dense nutrition diet than the S breed but requires less maintenance nitrogen.

Relationship of residual feed intake and protein efficiency in lactating cows fed high- or low-protein diets

Our objectives were to determine the repeatability of residual feed intake (RFI) across dietary protein levels and to determine the association between RFI and protein efficiency in lactating cows. Holstein cows (n = 166; 92 primiparous, 74 multiparous) with initial milk yield 41.3 ± 9.8 kg/d were fed diets with high or low protein in peak lactation. Experiments were conducted as crossovers with 2 treatment periods of 28 to 35 d. Production of 69 of the 166 cows (42 primiparous, 27 multiparous) was also measured in late lactation. Low-protein diets were 14% crude protein (CP) in peak lactation and 13% CP in late lactation and were formulated to contain adequate rumen-degradable protein to maintain rumen function. High-protein diets were 18% CP in peak lactation and 16% CP in late lactation and contained extra expeller soybean meal to increase absorbed protein. Cows were milked twice daily; DMI and milk yield were recorded daily. Milk composition was measured over 4 consecutive milkings weekly, and body weight (BW) was measured 3 times weekly. Fixed effects of diet, parity, and treatment period, interaction of parity and diet, and random effects of experiment and cow nested within experiment were included in the model to compare intake and production performance between cows fed different levels of CP. The RFI value was calculated for each cow on each treatment based on the actual intake, milk energy output, metabolic BW, and body energy (calculated from BW change and body condition score over the treatment period) change. Ranking of cows for RFI was moderately repeatable across dietary protein in peak lactation (r = 0.59) but less repeatable in late lactation (r = 0.41). Negative correlation was observed between RFI and protein efficiency values (dietary protein captured in milk) for cows in both peak lactation (r = -0.42) and late lactation (r = -0.24), which suggested that cows with higher energy efficiency had greater protein efficiency. In conclusion, RFI was repeatable across dietary protein levels within lactation stage, and cows with lower RFI values utilized protein more efficiently.

Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigate heat production associated with lactation in sows

BackgroundThe study objective was to test the hypothesis that 1) lowering dietary crude protein (CP) increases dietary energetic efficiency and reduces metabolic heat associated with lactation, and 2) excessive dietary leucine (Leu) supplementation in a low CP diet decreases dietary energetic efficiency and increases metabolic heat associated with lactation.MethodsFifty-four lactating multiparous Yorkshire sows were allotted to 1 of 3 isocaloric diets (10.80 MJ/kg net energy): 1) control (CON; 18.75% CP), 2) reduced CP with a near ideal or optimal AA profile (OPT; 13.75% CP) and 3) diet OPT with excessive Leu (OPTLEU; 14.25% CP). Sow body weight and backfat were recorded on day 1 and 21 of lactation and piglets were weighed on day 1, 4, 8, 14, 18, and 21 of lactation. Energy balance was measured on sows during early (day 4 to 8) and peak (day 14 to18) lactation, and milk was sampled on day 8 and 18.ResultsOver 21-day lactation, sows fed OPT lost body weight and body lipid (P < 0.05). In peak lactation, sows fed OPT had higher milk energy output (P < 0.05) than CON. Sows fed OPTLEU tended (P = 0.07) to have less milk energy output than OPT and did not differ from CON. Maternal energy retention was lower (P < 0.05) in OPT and OPTLEU compared to CON sows, and did not differ between OPTLEU and OPT sows. Sows fed OPT had higher (P < 0.05) apparent energy efficiency for milk production compared to CON. Heat production associated with lactation was lower (P < 0.05) or tended to be lower (P = 0.082), respectively, in OPT and OPTLEU compared to CON sows.ConclusionThe OPT diet, in peak lactation, improved dietary energy utilization for lactation due to less urinary energy and metabolic heat loss, and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization. Leucine supplementation above requirement may reduce dietary energy utilization for lactation by decreasing the energy partitioning towards milk, partially explaining the effectiveness of OPT diet over CON diets.

Exposure to artificial wind increases energy intake and reproductive performance of female Swiss mice (Mus musculus) in hot temperatures.

High temperatures and heatwaves are rapidly emerging as an important threat to many aspects of physiology and behavior in females during lactation. The body's capacity to dissipate heat is reduced by high ambient temperatures, increasing the risk of hyperthermia. Exposure to wind, a pervasive environmental factor for most terrestrial animals, is known to increase heat loss, but its effects on the reproductive performance of small mammals remains unclear. In the present study, the effects of wind on the energy budgets, resting metabolic rate and milk energy output (MEO) were measured in lactating Swiss mice at 21 and 32.5°C. Females kept at 32.5°C had a significantly lower resting metabolic rate, food intake and MEO, and lighter offspring, than those kept at 21°C. However, exposure to wind increased the asymptotic food intake of females kept at 32.5°C by 22.5% (P<0.01), their MEO by 20.7% (P<0.05) and their litter mass by 17.6% (P<0.05). The body temperature of females kept at 32.5°C was significantly higher during lactation than that of females kept at 21°C, but this difference was reduced by exposure to wind. These findings suggest that exposure to wind considerably improves reproductive performance, increasing the fitness of small mammals while undergoing hot temperatures during heatwaves.

Limits to sustained energy intake. XXXII. Hot again: dorsal shaving increases energy intake and milk output in golden hamsters (Mesocricetus auratus).

Golden hamsters have four times the body size of mice, raise very large litters and are required to produce large quantities of milk during the 18-day lactation period. We have previously proposed that they may be prone to being limited by their heat dissipation capacity. Studies where lactating females are shaved to elevate their heat dissipation capacity have yielded conflicting data so far. With their short pregnancy of ∼18 days, the large litters and the reported high skin temperatures, they may serve as an ideal model to elucidate the role of epilation for energy budgets in lactating mammals. We shaved one group of lactating females dorsally on the sixth day of lactation, and tested if the elevated heat dissipation capacity would enable them to have higher energy intakes and better food-to-milk conversion rates. Indeed, we observed that females from the shaved group had 6% higher body mass and 0.78°C lower skin temperature than control females during lactation. When focusing on the phase of peak lactation, we observed significantly higher (10%) gross energy intake of food and 23.4% more milk energy output in the shaved females, resulting in 3.3 g higher individual pup weights. We conclude that shaving off the females' fur, even though restricted to the dorsal surface, had large consequences on female energy metabolism in lactation and improved milk production and pup growth in line with our previous work on heat dissipation limitation. Our new data from golden hamsters confirm heat dissipation as a limiting factor for sustained metabolic rate in lactation in some small mammals and emphasise the large effects of a relatively small manipulation such as fur removal on energy metabolism of lactating females.

Fibroblast growth factor-21 (FGF21) administration to early-lactating dairy cows. II. Pharmacokinetics, whole-animal performance, and lipid metabolism

Dairy cows cope with severe energy insufficiency in early lactation by engaging in intense and sustained mobilization of fatty acids from adipose tissue. An unwanted side effect of this adaptation is excessive lipid accumulation in the liver, which in turn impairs hepatic functions. Mice experiencing increased hepatic fatty acid flux are protected from this condition through coordinated actions of the newly described hormone fibroblast growth factor-21 (FGF21) on liver and adipose tissue. The possibility of an analogous role for FGF21 in dairy cows is suggested by its rapid increase in plasma levels around parturition followed by chronically elevated levels in the first few weeks of lactation. To test this hypothesis, dairy cows were randomly assigned on d 12.6 ± 2.2 (± standard error) of lactation to receive either an excipient (control; n = 6) or recombinant human FGF21 (n = 7), first as an FGF21 bolus of 3 mg/kg of body weight (BW) followed 2 d later by a constant i.v. infusion of FGF21 at a rate of 6.3 mg/kg of metabolic BW for 9 consecutive days. After bolus administration, human FGF21 circulated with a half-life of 194 min, and its constant infusion increased total plasma concentration 117-fold over levels in excipient-infused cows. The FGF21 treatment had no effect on voluntary feed intake, milk yield, milk energy output, or net energy balance measured over the 9-d infusion or on final BW. Plasma fatty acids circulated at lower concentrations in the FGF21 group than in the control group for the 8-h period following bolus administration, but this reduction was not significant during the period of constant i.v. infusion. Treatment with FGF21 caused a 50% reduction in triglyceride content in liver biopsies taken at the end of the constant i.v. infusion without altering the mRNA abundance of key genes involved in the transport, acyl coenzyme A activation, or oxidation of fatty acids. In contrast, FGF21 treatment ablated the recovery of plasma insulin-like growth factor-1 seen in control cows during the 9-d i.v. infusion period despite a tendency for higher plasma growth hormone. This effect was associated with increased hepatic mRNA abundance of the intracellular inhibitor of growth hormone receptor trafficking, LEPROT. Overall, these data confirm the ability of FGF21 to reduce lipid accumulation in bovine liver and suggest the possibility that FGF21 does so by attenuating the hepatic influx of adipose tissue-derived fatty acids.

Altering the ratio of dietary C16:0 and cis-9 C18:1 interacts with production level in dairy cows: Effects on production responses and energy partitioning

The objective of our study was to evaluate the effects of altering the dietary ratio of palmitic (C16:0) and oleic (cis-9 C18:1) acids on nutrient digestibility, energy partitioning, and production responses of lactating dairy cows. Cows were blocked by milk yield and assigned to 3 groups (12 cows per group) in a main plot: low (45.2 ± 1.7 kg/d), medium (53.0 ± 1.6 kg/d), and high (60.0 ± 1.9 kg/d). Within each production group, a truncated Latin square arrangement of fatty acid (FA) treatments was used in 2 consecutive 35-d periods. The FA treatments supplemented at 1.5% of diet dry matter were (1) 80:10 (80% C16:0 + 10% cis-9 C18:1), (2) 73:17 (73% C16:0 + 17% cis-9 C18:1), (3) 66:24 (66% C16:0 + 24% cis-9 C18:1), and (4) 60:30 (60% C16:0 + 30% cis-9 C18:1). Treatment × production group interactions were observed for yields of milk, fat-corrected milk, energy-corrected milk, milk fat, milk protein, and milk lactose and energy partitioned to milk. Increasing cis-9 C18:1 in FA treatments reduced fat-corrected milk, energy-corrected milk, and milk energy output in low-producing cows but increased these in high-producing cows. Increasing cis-9 C18:1 in FA treatments did not affect milk yield, milk protein yield, and milk lactose yield in low- and medium-producing cows but increased these in high-producing cows. Regardless of production level, there was no effect of treatments on dry matter intake; however, increasing cis-9 C18:1 in FA treatments increased body weight change and body condition score change. Increasing cis-9 C18:1 in FA treatments increased total FA digestibility due to a linear increase in 16- and 18-carbon FA digestibilities. Interactions between FA treatments and production level were observed for the yield of milk fat and milk FA sources. In low-producing cows, increasing cis-9 C18:1 in FA treatments decreased milk fat yield due to a decrease in de novo and mixed milk FA without changes in preformed milk FA. In contrast, in high-producing cows, increasing cis-9 C18:1 in FA treatments increased milk fat yield due to an increase in de novo and preformed milk FA. Our results indicate that high-producing dairy cows (averaging 60 kg/d) responded better to a fat supplement containing more cis-9 C18:1, whereas low-producing cows (averaging 45 kg/d) responded better to a supplement containing more C16:0.

Diet starch concentration and starch fermentability affect energy intake and energy balance of cows in the early postpartum period

Our objective was to evaluate the effects of diet starch concentration and fermentability on energy intake and energy balance during the early postpartum (PP) period. Fifty-two multiparous Holstein cows were used in a randomized block design experiment with a 2 × 2 factorial arrangement of treatments. Treatment rations were formulated to 22% or 28% starch concentration (LS and HS, respectively) with dry ground corn (DGC) or high moisture corn (HMC) as the primary starch source. Rations were formulated for 22% forage neutral detergent fiber (NDF) and 17% crude protein and fed from 1 to 23 d PP. Starch concentration was adjusted by altering concentrations of corn grain and soyhulls. Dry matter intake and milk yield were measured daily, and milk components, milk composition, body condition score (BCS), body weight (BW), and back fat thickness (BFT) were measured weekly. Feeds and refusals as well as fecal samples were collected, and digestibility was determined weekly. High moisture corn (HMC) decreased dry matter and net energy (NEL) intakes compared with DGC more when included in an HS diet (3.9 kg/d and 3.2 Mcal/d) than in an LS diet (0.9 kg/d and 0.6 Mcal/d). The HMC treatment decreased NDF digestibility 3.7 percentage units compared with DGC when included in the HS diet but had little effect when included in an LS diet. Compared with DGC, HMC increased weekly BW and BFT loss when included in an HS diet (-34.7 vs. -8.4 kg/wk and -0.12 vs. -0.10 cm/wk) and decreased weekly BW loss but increased weekly BFT loss when included in an LS diet (-18.9 vs. -21.4 kg/wk and -0.11 vs. -0.02 cm/wk). Weekly BCS loss increased for HMC compared with DGC (-0.33 vs. -0.23 unit/wk). High moisture corn also decreased milk NEL output compared with DGC (28.2 vs. 31 Mcal/d), but had little effect on energy balance, which was improved by HS compared with LS (-14.7 vs. -16.8 Mcal/d). Over time, concentrations of milk de novo fatty acids (<16 carbons) increased and concentration of milk preformed fatty acids (>16 carbons) decreased for all treatments, but yields of both sources as well as yield of mixed fatty acids (C16:0 plus C16:1 cis-9 and iso-C16:0) decreased over time with increased SF. Feeding HMC decreased energy intake and milk energy output, but it had little effect on energy balance during the early PP period.

Effect of experimental design on responses to 2 concentrations of metabolizable protein in multiparous dairy cows

The objective of this research was to characterize the implications of changing between diets formulated to be adequate (ADMP) or low (LOMP) in metabolizable protein in a Latin square (LSq) design or of feeding the same diets continuously in a randomized complete block experimental design (RCBD). Fifty-four multiparous early-lactation cows (initial average ± SD; parity 2.8 ± 0.9, 85.8 ± 31 d in milk, 715 ± 63 kg of body weight, 29.1 ± 2.7 kg of dry matter intake/d, and 57.7 ± 5.7 kg of milk yield/d) were blocked by parity and days in milk and were then randomly assigned to experimental design, with 16 cows assigned to LSq and 38 cows assigned to RCBD. Cows within blocks in LSq were randomly assigned to sequence in a 4-sequence, 4-period, 2-treatment LSq balanced for the effects of previous treatment carryover. Cows within blocks in RCBD were randomly assigned to dietary treatment, which was fed over the same four 28-d periods as the cows in LSq. Treatment diets were formulated to be similar in composition with the exception of exchanging an equal quantity of expeller soybean meal from ADMP (16.5% crude protein; 28.4% ash-free, amylase-treated neutral detergent fiber organic matter) for soybean hulls in LOMP (14.6% crude protein; 31.1% ash-free, amylase-treated neutral detergent fiber organic matter). Cows were individually fed treatment diets in a tiestall barn once daily for ad libitum consumption, milked 3 times daily, and administered recombinant bovine somatotropin every 14 d. Milk yield and feed offered and refused were measured daily; BW was recorded on 2 consecutive days each week; milk composition was measured at 6 consecutive milkings each week; and spot samples of feces, urine, and blood were collected during the last week of each period and a covariate period. Experimental designs were analyzed separately using results from wk 4 of each period with mixed effects modeling. Dry matter intake and milk fat yield were not affected by diet in either design, whereas milk and protein yields were greater for cows fed ADMP in both designs. Milk fat and protein percentage responses and milk energy output inferences were different between designs. Milk fat yield and percentage responses were affected by previous treatment carryover in LSq. Metabolic and digestibility inferences were very similar between designs. Under the conditions of this experiment, inferences on N metabolism and the majority of production measurements were not affected by experimental design, with the principal exceptions of milk fat and protein percentage and milk energy output.

The use of whole body calorimetry to compare measured versus predicted energy expenditure in postpartum women

Accurate assessment of energy expenditure may support weight-management recommendations. Measuring energy expenditure for each postpartum woman is unfeasible; therefore, accurate predictive equations are needed. This study compared measured with predicted resting energy expenditure (REE) and total energy expenditure (TEE) in postpartum women. This was a longitudinal observational study. REE was measured at 3 mo postpartum (n=52) and 9 mo postpartum (n=49), whereas TEE was measured once at 9 mo postpartum (n=43) by whole body calorimetry (WBC). Measured REE (REEWBC) was compared with 17 predictive equations; measured TEE plus breast milk energy output (ERWBC) was compared with the estimated energy requirements/Dietary Reference Intakes equation (EERDRI). Fat and fat-free mass were measured by dual-energy X-ray absorptiometry. Group-level agreement was assessed by the Pearson correlation, paired t test, and Bland-Altman (bias) analyses. Individual-level accuracy was assessed with the use of Bland-Altman limits of agreement, and by the percentage of women with predicted energy expenditure within 10% of measured values ("accuracy"). The cohort was primarily Caucasian (90%). At a group level, the best equation predicting REEWBC was the DRI at 3 mo postpartum (-7 kcal, -0.1%; absolute and percentage bias, respectively), and the Harris-Benedict at 9 mo postpartum (-17 kcal, -0.5%). At an individual level, the Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU) height and weight equation was the most accurate at 3 mo postpartum (100% accuracy) and 9 mo postpartum (98% accuracy), with the smallest limits of agreement. Equations including body composition variables were not more accurate. Compared with ERWBC, EERDRI bias was -36 kcal, with inaccurate predictions in 33% of women. Many REE predictive equations were accurate for group assessment, with the FAO/WHO/UNU height and weight equation having the highest accuracy for individuals. EERDRI performed well at a group level, but inaccurately for 33% of women. A greater understanding of the physiology driving energy expenditure in the postpartum period is needed to better predict TEE and ultimately guide effective weight-management recommendations.

Three-breed rotational crossbreds of Montbéliarde, Viking Red, and Holstein compared with Holstein cows for feed efficiency, income over feed cost, and residual feed intake

Rotational 3-breed crossbred cows of Montbéliarde, Viking Red, and Holstein (CB) were compared with Holstein (HO) cows for alternative measures of feed efficiency as well as income over feed cost (IOFC) and residual feed intake (RFI) during the first 150 d of first, second, and third lactations. Primiparous and multiparous CB (n = 63 and n = 43, respectively) and HO (n = 60 and n = 37, respectively) cows were fed the same total mixed ration twice daily with refusals weighed once daily. Feed was analyzed for dry matter content, net energy for lactation, and crude protein content. Body weight (BW) was recorded twice weekly. Daily production of milk, fat, and protein were estimated from monthly test days with best prediction. Measures of efficiency from 4 to 150 d in milk (DIM) were feed conversion efficiency (FCE), defined as fat plus protein production (kg) per kilogram of dry matter intake (DMI); ECM/DMI, defined as kilograms of energy-corrected milk (ECM) per kilogram of DMI; net energy for lactation efficiency (NELE), defined as ECM (kg) per megacalorie of net energy for lactation intake; crude protein efficiency (CPE), defined as true protein production (kg) per kilogram of crude protein intake; and DMI/BW, defined as DMI (kg) per kilogram of BW. The IOFC was defined as revenue from fat plus protein production minus feed cost. The RFI from 4 to 150 DIM for each lactation was the residual error remaining from regression of DMI on milk energy output (Mcal), metabolic BW, and energy required for change in BW (Mcal). Statistical analysis of measures of feed efficiency and RFI for primiparous cows included the fixed effects of year of calving and breed group. For multiparous cows, statistical analysis included breed as a fixed effect and cow as a repeated effect nested within breed group. Primiparous CB cows had higher means for FCE (+5.5%), ECM/DMI (+4.0%), NELE (+4.0%), and CPE (+5.2%) and a lower mean DMI/BW (-5.3%) than primiparous HO cows. Primiparous CB cows ($875) also had higher mean IOFC than primiparous HO cows ($825). In addition, mean RFI from 4 to 150 DIM was significantly lower (more desirable) for primiparous CB cows than HO cows. Likewise, multiparous CB cows had higher means for FCE (+8.2%), ECM/DMI (+5.9%), NELE (+5.8%), and CPE (+8.1%) and a lower mean for DMI/BW (-4.8%) than multiparous HO cows. Multiparous CB cows ($1,296) also had a higher mean for IOFC than multiparous HO cows ($1,208) and a lower mean for RFI from 4 to 150 DIM than HO cows.

Postpartum supplementation of fermented ammoniated condensed whey improved feed efficiency and plasma metabolite profile

Postpartum dietary supplementation of gluconeogenic precursors may improve the plasma metabolite profile of dairy cows, reducing metabolic disorders and improving lactation performance. The objective of this trial was to examine the effects of supplementation with fermented ammoniated condensed whey (FACW) postpartum on lactation performance and on profile of plasma metabolites and hormones in transition dairy cows. Individually fed multiparous Holstein cows were blocked by calving date and randomly assigned to control (2.9% dry matter of diet as soybean meal; n = 20) or FACW (2.9% dry matter of diet as liquid GlucoBoost, Fermented Nutrition, Luxemburg, WI; n = 19) dietary treatments. Treatments were offered from 1 to 45 d in milk (DIM). Cows were milked twice a day. Dry matter intake and milk yield were recorded daily and averaged weekly. Individual milk samples from 2 consecutive milkings were obtained once a week for component analysis. Rumen fluid was collected (n = 3 cows/treatment) at 4 time points per day at 7 and 21 DIM. Blood samples were collected within 1 h before feeding time for metabolite analysis and hyperketonemia diagnosis. Supplementation of FACW improved feed efficiency relative to control; this effect may be partially explained by a marginally significant reduction in dry matter intake from wk 3 to 7 for FACW-supplemented cows with no detected FACW-driven changes in milk yield, milk protein yield, and milk energy output compared with control. Also, there was no evidence for differences in intake of net energy for lactation, efficiency of energy use, energy balance, or body weight or body condition score change from calving to 45 DIM between treatments. Supplementation of FACW shifted rumen measures toward greater molar proportions of propionate and butyrate, and lesser molar proportions of acetate and valerate. Cows supplemented with FACW had greater plasma glucose concentrations in the period from 3 to 7 DIM and greater plasma insulin concentrations compared with control. Plasma nonesterified fatty acid and β-hydroxybutyrate concentrations were decreased in cows supplemented with FACW compared with control cows in the period from 3 to 7 DIM. These findings indicate that FACW may have improved the plasma metabolite profile immediately postpartum in dairy cows. Additionally, supplementation of FACW resulted in improved feed efficiency as accessed by measures of milk output relative to feed intake.

Energy Balance Data from Lactating Dairy Goats Offered Total Mixed Diets

The objective of the study was to develop a univariate model for analyzing energy balance data from lactating goats at mid lactation and determine maintenance requirements and partial efficiencies of energy utilization. Energy balance data from eight studies involving lactating Murciano-Granadina goats fed total mixed diets, which accounted for a variation in metabolizable energy (MEI) intake, milk energy output (EI), and tissue energy balance, were used. The database included records obtained by indirect calorimetry. Data were adjusted with a mixed model that included the study as a random effect. Then, two multivariate linear models were obtained: metabolizable and net energy models. The metabolizable model was MEI=β0+β2E1+β3Tg+β4T1+e and the net energy model was E1=β0+β1MEI+β2Tg+β3T1+e; where β0, β1, β2 and β3 were the parameters, Tg was tissue energy retention and Tl the milk energy derived from body stores. For a better fitted proposed model, net energy for maintenance (NEm) was 283 kJ/kg of Body Weight 0.75 (BW) per day, and the efficiency of utilization of ME for lactation (k1), body weight gain (kg) and body tissue mobilization for milk production (kt) were 62%, 83% and 78%, respectively. Maintenance requirements and partial efficiencies for milk production and tissue energy mobilization were similar to the values proposed by INRA (2018). The increase in the efficiency of utilizing dietary energy for gain, compared with other feeding systems, was partially attributed to the stage of lactation, due to that goats were feeding at mid lactation.

Energy and nitrogen partitioning in dairy cows at low or high metabolizable protein levels is affected differently by postrumen glucogenic and lipogenic substrates

This study tested the effects of energy from glucogenic (glucose; GG) or lipogenic (palm olein; LG) substrates at low (LMP) and high (HMP) metabolizable protein levels on whole-body energy and N partitioning of dairy cattle. Six rumen-fistulated, second-lactation Holstein-Friesian dairy cows (97 ± 13 d in milk) were randomly assigned to a 6 × 6 Latin square design in which each experimental period consisted of 5 d of continuous abomasal infusion followed by 2 d of rest. A total mixed ration consisting of 42% corn silage, 31% grass silage, and 27% concentrate (dry matter basis) was formulated to meet 100 and 83% of net energy and metabolizable protein requirements, respectively, and was fed at 90% of ad libitum intake by individual cow. Abomasal infusion treatments were saline (LMP-C), isoenergetic infusions (digestible energy basis) of 1,319 g/d of glucose (LMP-GG), 676 g/d of palm olein (LMP-LG; major fatty acid constituents are palmitic, oleic, and linoleic acid), or 844 g/d of essential AA (HMP-C), or isoenergetic infusions of 1,319 g/d of glucose + 844 g/d of essential AA (HMP-GG) or 676 g/d of palm olein + 844 g/d of essential AA (HMP-LG). The experiment was conducted in climate respiration chambers to determine energy and N balance in conjunction with milk production and composition, nutrient digestibility, and plasma constituents. Infusion of GG and LG decreased dry matter intake, but total gross energy intake from the diet plus infusions was not affected by GG or LG. Furthermore, GG or LG did not affect total milk, protein, or lactose yields. Infusing GG or LG at the HMP level did not affect milk production differently than at the LMP level. Infusion of GG stimulated energy retention in body tissue, increased plasma glucose and insulin concentrations, decreased lipogenic metabolites in plasma, and decreased milk fat yield and milk energy output. Nitrogen intake decreased and milk N efficiency increased in response to GG, and N retention was not affected. Infusion of LG tended to increase metabolizable energy intake, increased milk fat yield and milk energy output, increased plasma triacylglycerides and long-chain fatty acid concentrations, and had no effect on energy retention. Infusion of LG decreased N intake but did not affect milk N efficiency or N retention. Compared with the LMP level, the HMP level increased dry matter intake, gross and metabolizable energy intake, and total milk, fat, protein, and lactose yields. Milk energy output increased at the HMP level, and protein level did not affect total energy retention. Heat production increased at the HMP level, but only when GG and LG were infused. The HMP level increased N intake, milk N output, and plasma urea concentration, tended to increase N retention, and decreased milk N efficiency. Regardless of protein level, GG promoted energy retention and improved milk N efficiency, but not through increased milk protein yield. Infusion of LG partitioned extra energy intake into milk and had no effect on milk N efficiency.

Effects of timing of palmitic acid supplementation during early lactation on nutrient digestibility, energy balance, and metabolism of dairy cows

The objective of our study was to evaluate the effects of timing of palmitic acid (C16:0) supplementation during early lactation on nutrient digestibility, energy intake and balance, and metabolic responses of dairy cows. Fifty-two multiparous cows were used in a randomized complete block design experiment. During the fresh (FR) period (1-24 d in milk) cows were assigned to either a control diet containing no supplemental fat (CON) or a C16:0-supplemented diet [PA; 1.5% of diet dry matter (DM)]. During the peak (PK) period (25-67 d in milk) cows were assigned to either a CON diet or a PA diet (1.5% of diet DM) in a 2 × 2 factorial arrangement of treatments considering the diet that they received during the FR period. During the FR period, compared with CON, PA increased DM digestibility by 3.0 percentage units and neutral detergent fiber (NDF) digestibility by 4.4 percentage units, and the increase in these variables was consistent over time. Although PA did not affect 18-carbon fatty acid (FA) digestibility, it decreased 16-carbon FA digestibility by 10.8 percentage units and total FA digestibility by 4.7 percentage units compared with CON. We observed a tendency for an interaction between treatment and time for total FA digestibility and 16-carbon FA digestibility due to the difference in FA digestibility between PA and CON reducing over time. Compared with CON, PA increased digestible energy intake by 3.9 Mcal/d, metabolizable energy intake by 3.5 Mcal/d, and net energy for lactation intake by 2.5 Mcal/d. The PA diet also increased milk energy output, negative energy balance, and plasma nonesterified fatty acid concentration and reduced plasma insulin concentration. We also observed a tendency for an interaction between treatment and time for energy balance due to cows receiving the PA treatment being in a greater negative energy balance over time. During the PK period, PA increased DM digestibility by 2.9 percentage units and NDF digestibility by 3.5 percentage units compared with CON. Although PA decreased 16-carbon FA digestibility by 7.0 percentage units, PA did not affect 18-carbon FA digestibility or total FA digestibility. Feeding PA during the PK period increased energy intake and milk energy output and did not affect energy balance. In conclusion, feeding a C16:0 supplement to early-lactation cows consistently increased DM and NDF digestibilities and energy intake compared with a control diet containing no supplemental fat. Feeding C16:0 markedly increased milk energy output in both the FR and PK periods but increased negative energy balance only in the FR period.

Prepartum supplementation of conjugated linoleic acids (CLA) increased milk energy output and decreased serum fatty acids and β-hydroxybutyrate in early lactation dairy cows.

Prepartum supplementation with conjugated linoleic acid (CLA) may influence lipolysis and hyperketonemia in dairy cows. The objective of this study was to examine the effect of prepartum CLA supplementation on lactation performance and serum fatty acids (FA) and β-hydroxybutyrate (BHB) in early lactation dairy cows, and secondarily on reproductive performance. Multiparous cows were enrolled in the study at 18 days prior to expected calving date, and randomly assigned 100 g/day of Lutrell Pure (BASF, Ludwigshafen, Germany; 75% FA), providing 10 g/day of each CLA isomer (trans-10 cis-12 and cis-9 trans-11 CLA) or equivalent amount of rumen inert fatty acids as control (78 g/day of Energy Booster 100; Milk Specialties Global, Eden Prairie, MN). Treatments were top dressed daily to individual cows from enrollment to calving and all cows were offered the same ration. Blood samples were collected on the first day of supplementation, 10 days prepartum, and 1, 7, 14, and 30 days postpartum. Hyperketonemia was defined as serum BHB ≥ 1.2 mM. Milk yield was recorded daily until 60 days postpartum and averaged weekly. Milk samples were obtained weekly for component analysis. Prepartum CLA supplementation tended to increase serum concentration of cis-9, trans-11 CLA and increased trans-10, cis-12 CLA prepartum. Cows supplemented with CLA had increased milk protein yield and tended to have increased milk fat yield and milk yield, which together resulted in greater energy content of milk. Cows supplemented with CLA had lower serum FA on day 1 and 7 postpartum and overall lower serum BHB postpartum, which resulted in decreased prevalence of hyperketonemia on day 14 postpartum. There were no differences in body condition score change, other health disorders, or reproductive outcomes by treatment. Together, these findings indicate that prepartum CLA supplementation may be a plausible strategy to positively influence postpartum performance.

Short communication: Comparison of a palmitic acid-enriched triglyceride supplement and calcium salts of palm fatty acids supplement on production responses of dairy cows

The objective of our study was to evaluate the effects of feeding a palmitic acid-enriched triglyceride supplement or a calcium salts of palm fatty acid (FA) supplement on nutrient digestibility and production responses of mid-lactation dairy cows. Fifteen Holstein cows (139 ± 39 d in milk) were randomly assigned to treatment sequence in a 3 × 3 Latin square design. Treatments were a control diet (CON; no fat supplement) and 1.5% of FA added either as a palmitic acid-enriched triglyceride supplement (PA-TG) or as calcium salts of palm FA supplement (Ca-FA). Fat-supplemented treatments did not affect dry matter intake (DMI) compared with CON, but Ca-FA reduced DMI compared with PA-TG. Compared with CON, fat-supplemented treatments increased 18-carbon FA digestibility by 2.0 percentage units but did not affect digestibility of total FA or 16-carbon FA. Compared with Ca-FA, PA-TG reduced total FA digestibility by 8.7 percentage units due to a decrease in 16-carbon FA digestibility (21.7 percentage units). Both fat supplements increased neutral detergent fiber (NDF) digestibility compared with CON (3.90 percentage units), and PA-TG tended to increase NDF digestibility by 1.60 percentage units compared with Ca-FA. Compared with CON, fat-supplemented treatments increased milk yield (1.05 kg/d), 3.5% fat-corrected milk yield (2.20 kg/d), and energy-corrected milk yield (1.80 kg/d). Also, PA-TG increased milk fat yield (50 g/d) and milk energy output (1.0 Mcal/d) and tended to increase milk fat content (0.07 percentage units) and energy-corrected milk yield (1.0 kg/d) compared with Ca-FA. Fat-supplemented treatments reduced the yield of de novo milk FA (23 g/d) and increased the yields of mixed (43 g/d) and preformed (52 g/d) milk FA compared with CON. The PA-TG treatment increased the yield of 16-carbon (66 g/d) milk FA compared with Ca-FA, whereas Ca-FA increased the yield of preformed (60 g/d) milk FA. Fat-supplemented treatments increased intake of net energy for lactation by 1.80 Mcal/d, milk energy output by 1.30 Mcal/d, and energy in body reserves by 0.30 Mcal/d compared with CON. The Ca-FA treatment increased energy allocated to body reserves (0.60 Mcal/d), energy partitioning toward body reserves (1.20 percentage units), and body condition score change (0.06 units), and tended to increase body weight change (0.16 kg/d) and body condition score (0.08 units) compared with PA-TG. In conclusion, feeding a palmitic acid-enriched triglyceride supplement increased milk energy output due to increased yields of milk and milk fat, whereas feeding a calcium salts of palm FA supplement increased FA digestibility and energy partitioned to body reserves.

Impacts of increasing levels of canola meal in diets of high producing Holstein cows on their productive performance

Ingredient substitution studies are common in the animal science literature. However such studies often confound changes of ingredient and nutrient levels, thereby begging the question as to whether responses measured among diets represent known differences among diets in measured nutrient levels, or to changes in unknown dietary factors/nutrients. Our objective was to determine if formulating diets to contain the same levels of nutrients, concomitant with increasing the dietary canola meal (CM) level from 50 to 170 g/kg of diet dry matter (DM), while mainly reducing levels of distillers dried grains (DDG), would result in dissimilar performance by lactating dairy cattle – thereby suggesting nutritional factors/nutrients of CM and/or DDG exist which are not known and so not included in diet formulation. This differs from Swanepoel et al. (2014; Anim. Feed Sci. Technol. 189, 41–53) wherein increasing levels of CM were confounded with modest changes in dietary levels of some proximate nutrients. The experiment was a 4 × 4 Latin square using 4 pens of about 315 early lactation multiparous cows/pen with four 21 day periods. The DM intake was not affected (30.0 ± 0.09 kg/d) by increased dietary levels of CM, but milk, milk lactose and milk energy outputs all declined (P < 0.01) linearly, as did milk somatic cell counts. Change in body condition score (BCS) declined linearly (P < 0.01), with a quadratic component (P < 0.01), suggesting maximum BCS gain at about 80 g/kg CM inclusion. Plasma concentrations of most essential amino acids increased linearly (P < 0.01) with higher dietary levels of CM – exceptions being Met and Phe (unaffected) and Leu (declined). As a result of lower milk energy output and lower accretion of energy in BCS gain, as well as similar DM intake, estimated net energy for lactation (NEl) of the diet declined linearly as inclusion of CM increased. While our objective of creating diets with no changes in dietary nutrient levels and biological measures was mainly met, there was an unexpected linear (P < 0.01) decrease of 6.3 g/kg DM in the crude fat level of the diets concomitant with the increase in CM inclusion. However the calculated decrease of diet NEl as a direct result of this difference in diet crude fat only accounted for about 40% of the decline in the estimated NEl density of the diet (i.e., 0.08 MJ/kg DM of NElversus the actual decline of 0.21 MJ/kg DM of NEl). This suggests that if the diets had achieved equal fat levels, as well as other nutrients, concomitant with increasing levels of CM, that NEl output of the cows would have still declined. Thus diets formulated with 170 g/kg of CM in diet DM (from 50 g/kg DM of CM) in substitution for primarily corn based DDG, but with equal levels of primary nutrients, resulted in a small reduction in performance of lactating dairy cows for reasons which are unknown, but may relate to lower conversion of digestible to metabolizable energy of the soluble carbohydrate fraction of CM versus DDG.

Identification of biological traits associated with differences in residual energy intake among lactating Holstein cows

Residual feed intake, which is usually used to estimate individual variation of feed efficiency, requires frequent and accurate measurements of individual feed intake to be carried out. Developing a breeding scheme based on residual feed intake in dairy cows is therefore complicated, especially because feed intake is not measurable for a large population. Another solution could be to focus on biological determinants of feed efficiency, which could potentially be directly and broadband measurable on farm. Several phenotypes have been identified in literature as being associated with differences in feed efficiency. The present study therefore aims to identify which biological mechanisms are associated with residual energy intake (REI) differences among dairy cows. Several candidate phenotypes were recorded frequently and simultaneously throughout the first 238 d in milk for 60 Holstein cows fed on a constant diet based on maize silage. A multiple linear regression of the 238 d in milk average of net energy intake was fitted on the 238 d in milk averages for milk energy output, metabolic body weight, the sum over the 238 d in milk of both, body condition score loss and gain, and the residuals were defined as REI. A partial least square regression was fitted over all biological traits to explain REI variability. Linear multiple regression explained 93.6% of net energy intake phenotypic variation, with 65.5% associated with lactation requirement, 23.2% with maintenance, and 4.9% with body reserves change; the 6.4% residuals represented REI. Overall, measured biological traits contributed to 58.9% of REI phenotypic variability, which were mainly explained by activity (26.5%) and feeding behavior (21.3%). However, apparent confounding was observed between behavior, activity, digestibility, and rumen-temperature variables. Drawing a conclusion on biological traits that explain feed efficiency differences among dairy cows was not possible due to this apparent confounding between the measured variables. Further investigation is needed to validate these results and to characterize the causal relationship of feed efficiency with feeding behavior, digestibility, body reserves change, activity, and rumen temperature.