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The Effects of Feed Supplements on the Production, Metabolism, and Behavior of Dairy Cows Fed Low Levels of Concentrates During Lactation
C. J. C. Phillips, MA, PhD*‡
S. E. Kitwood, PhD, MRCVS†
*Department of Clinical Veterinary Medicine,
†School of Agricultural and
KEY WORDS: requirements, malnutrition, supplement, lactation
The welfare of dairy cows could be adversely affected by offering insufficient concentrate supplement before or during lactation. An experiment was conducted in which supplementary feeding during the transition or lactation period was compared for dairy cows offered a low level of concentrates during lactation. Only cows that had received supplementary feeding during the transition period, and consequently calved in a high body condition, increased their milk yield in response to the lactation supplement. These cows had increased plasma creatinine concentration, indicative of protein catabolism. Total food intake was not increased by the lactation supplement. Those cows that did not receive the transition period supplement did not increase milk yield in response to the lactation supplement, but they increased their silage intake. Offering a supplement during lactation reduced plasma lactate dehydrogenase, indicative of improved protein and energy nutrition, but it increased aggression between cows. It is concluded that there was no evidence that the welfare of cows fed a low level of concentrates without supplementary feeding was compromised, because they reduced their milk yield accordingly. The only evidence of adverse effects on welfare was when cows in a high level of body condition at calving were provided with a lactation supplement, because this caused them to increase milk yield, which was not supported by increased food intake, and cows offered the lactation supplement had increased levels of aggression.
Consideration of minimum levels of nutrition for livestock
is increasing in importance where economic pressure on farmers forces
them to reduce the levels of feed offered to their animals. In 1998
When lactating dairy cows are fed moderate concentrate intakes, their forage intake can be reduced for periods of approximately 3 weeks by up to 40% of ad libitum intake without affecting milk production.3 More than this will reduce production, in particular, milk protein output, and result in considerable losses in body weight. This is most likely to occur at the end of the winter housing period, when insufficient forage has been harvested the previous summer. However, in critical times for the dairy industry such as during a major disease outbreak or at times of low milk price, reductions in the amount of purchased concentrates fed to dairy cows are a more likely cause of undernutrition. Constraints on output can also induce farmers to reduce feeding levels to their cows; in the mid 1980s, the introduction of milk quotas in the United Kingdom resulted in reductions in the amount of concentrate fed to dairy cows.4 Such restrictions in concentrate intake can cause undernutrition in lactating dairy cows, even if they have fodder permanently available, because of their large nutrient requirements in relation to their appetite. The diet composition is critical at such times, because reduced energy intake can be partially offset by increased catabolism of body fat reserves, but protein reserves are less readily mobilized.5,6 Protein breakdown in early lactation cows can be indicative of poor welfare.
An experiment was conducted to investigate whether the feeding of supplements to cows receiving low levels of concentrates during lactation will improve their welfare, as assessed from their physiology, behavior, and production. Supplementary feeding was either extra food offered during the transition period (resulting in an increase in fat stores in preparation for lactation) or high-quality supplements offered during lactation.
Materials and method
A 2-factor factorial experiment was conducted between August and the following March (factor 1: high and low transition period feeding, and factor 2: with or without provision of a lactation supplement). Forty-four multiparous Holstein–Friesian cows were paired at the end of lactation (mean 12 weeks before calving) by predicted calving date, body condition score, live weight, and milk production during the previous lactation. Within pairs they were randomly allocated to 2 treatments (high and low transition period feeding [TPF]) to achieve mean BC scores of approximately 4 (high TPF) and 2.5 (low TPF) at calving assessed on a 5-point scale.7 From entry to the experiment until calving, cows on the high TPF treatment received 1 kg DM per day of rolled barley and were stocked at a mean of 2.5 cows/hectare up to calving, whereas cows on the low TPF treatment received no barley and were stocked at a mean of 3.5 cows/hectare. The combination of pasture and concentrate restriction for cows in low TPF attempted to ensure that forage:concentrate ratio was not affected by the low level of feeding. BC scores were assessed weekly, and stocking rates on the perennial rye grass sward were adjusted to attempt to achieve the target BC scores at calving. The actual scores at calving were 4.0 (standard error [SE] 0.09) for the high TPF treatment and 2.7 (SE 0.11) for the low TPF treatment. Following calving (mean, October 10, SE 19 days), cows in each TPF treatment were allocated to pairs on the basis of calving date, BC score, parity, live weight, and milk production during the previous lactation. At day 7 postpartum, one cow from each pair was allocated to receive ad libitum grass silage and 3 kg per day of concentrate (treatment No Lactation Supplement [NoLS]). The other cow was allocated to the same ration but with the addition of 1 kg DM of a high-quality supplement (Supercharge Dairy®, Colborn Dawes Nutrition Ltd., Heanor, UK) (treatment Lactation Supplement [LS]). By weight, the concentrate contained 29% barley, 31% brewers’ grains, 32% molasses, and 8% minerals/vitamins. The supplement contained 37% Chilean fish meal (67% CP), 12% meat and bone meal (47 and 14% CP, respectively), 5% soybean meal, 9% wheat middlings, 8% molasses, 29% minerals, and had a mean chemical composition of 97% oven DM content, 37% crude protein in the DM, and a predicted metabolizable energy concentration of 13.0 MJ/kg DM.
Silage was from a regrowth of perennial rye grass (Lolium perenne) that was harvested after a short wilt by a precision chop forage harvester on July 3 to 5. A formic acid additive was applied during harvesting at 3.5 L/tonne. Cows were fed the rations as a TMR in their treatment groups daily using a mixer wagon (Keenan Easifeeder 140 FP), and refusals were weighed back once weekly. Individual TMR intakes were estimated by apportioning the treatment mean DMI according to individual metabolizable energy (ME) outputs,8 calculated from energy standards for maintenance, live weight change, and milk production.9
Milk production was recorded at 2 consecutive milkings weekly, and separate aliquot samples of milk were analyzed for fat, protein, and lactose contents. BC and live weight were recorded weekly. The silage, TMR, and concentrate ingredients were analyzed weekly for DM, CP, modified ADF (MADF), and ash (Table 1). Additionally, silage was analyzed for ammonia N and pH. The rumen degradability of protein in silage and concentrate was measured in 4 fistulated steers by the polyester bag method.10 The fractional outflow rate was assumed to be 0.08/h. Milk and feeds were analyzed according to the procedures of the U.K. Ministry of Agriculture, Fisheries and Food.11
Cow social and sexual behavior was observed by a single observer for 4 periods daily throughout the experiment, with 30-minute observations commencing at 05.45 (artificial dawn), 10.30, 14.15 and 22.30 (with artificial dusk at 23.00) hours. Artificial light was provided by 3 400-W halogen lights illuminating the 2 treatment areas. The following behaviors were recorded:
Aggression—3 types of aggression were recognized and recorded: 1) intention movements, where the head was swung in the direction of a conspecific, who took avoidance action; 2) bunting, use of the head by one cow to physically displace another; 3) pushing, deliberate use of a part of the body, other than the head to physically displace a subordinate.
Grooming—licking the front half of the body of another cow.
Standing to be mounted—a cow allowing herself to be mounted by another cow without attempting to escape.
Attempted mounting—attempt(s) (either successful or unsuccessful) to raise the anterior part of the body over the posterior of another cow.
Sniffing or licking the anogenital area of another cow.
Chin rubbing—pressing, resting, or rubbing the chin on the rump area of another animal.
Behavior was recorded from a 1-m high platform running the length of the cubicle house between the feeding passage and the cubicles. Events were recorded whenever a bout of activity occurred continuously for more than 5 seconds. Activities that ceased and were then reestablished between the same animals were recorded as separate events if a time interval of at least 5 seconds had elapsed between the end of one bout and the next.
Cow reproductive performance was monitored even though numbers of animals per treatment were only sufficient to determine major effects of treatment. Cows were artificially inseminated when observed standing to be mounted by another cow using a single straw of semen containing approximately 20 million spermatozoa. The semen used was from 5 Holstein–Friesian bulls, equally used between treatments. The postpartum interval to first service was calculated for all cycling animals (there was no significant difference between treatments in the number of animals not cycling). The interval from calving to pregnancy was determined from the date of calving in the following calving season, assuming a 281-day pregnancy.
A single blood sample was collected into a heparinized Vacutainer from each cow on the morning of the day of service by coccygeal venipuncture. After samples were taken for glucose analysis, they were centrifuged at 1500 rpm for 30 minutes and frozen at -15˚C before analysis for urea, albumin, globulin, creatinine, and lactate dehydrogenase (LDH) by a discrete multitest photometric analyzer (G400; Greiner Electronics, Langenthal, Switzerland). Duplicate prediluted blood samples were prepared and reactions were measured at 37˚C in an 8-cuvette photometer, each with a different wavelength. The following methods were used for analysis: glucose,12 creatinine,13 urea,14 lactate dehydrogenase14 (EC 22.214.171.124).15 For the total protein and albumin measurements, the Biuret and bromocresol green methods were used, respectively. Globulin concentrations were calculated as total protein minus albumin concentrations.
All data were initially tested for normality of data within treatments using the N-score statistic of Minitab.16 Production, reproduction, and blood biochemistry data were normally distributed, and the significance of treatment differences was examined by a general linear model of the effects of transition period feeding and lactation supplement treatments, and the cow pairs. The behavior data was not normally distributed, even after a variety of transformations. The Sign and Wilcoxon nonparametric tests were therefore used when the proportion of zeros in the data was greater and less than 50% respectively.17 The effects of the transition period feeding on behavior were not significant (P >0.10) and results are therefore presented for the effects of lactation supplement only.
During the lactation, the cows in the high TPF treatment did not increase their total or silage DM intake in response to the lactation supplement, but those in the low TPF treatment did (Table 2). Cows in the LS treatment consumed a diet with a decreased ratio of forage DM to concentrate DM, an increased crude protein, and in particular rumen-undegradable protein (RUP) content, and a similar dietary ME content, compared with that consumed by cows in the NoLS treatment (Table 1).
The milk production of cows in the high TPF treatment was increased by the lactation supplement, but that of cows in the low TPF treatment was not. Milk fat and lactose concentrations were not affected by treatment. Milk protein concentration was increased by the lactation supplement only for cows in the low TPF treatment. For cows in the high TPF treatment (that had calved in high BC), BC decreased when they were offered the lactation supplement, relative to cows offered no supplement. There were no effects of the feeding treatments on calving to first service or pregnancy intervals, or on the number of services per pregnancy.
Blood glucose concentration tended to be reduced for cows fed the lactation supplement (Table 3). Urea N concentration was reduced and globulin concentration increased for cows in the low TPF treatment that were fed the lactation supplement. Creatinine and albumin concentrations were greater and LDH concentrations were reduced for cows fed the lactation supplement. All metabolites were within the reference ranges.
Transition period feeding did not affect cow behavior during lactation. There were no effects of the lactation supplement on mounting or chin rubbing behavior, but it increased aggression and sniffing, licking, and grooming activities (Table 4).
Cows that calved in high BC after receiving the supplement in the transition period responded to the lactation supplement by increasing their milk production. This was supported by mobilization of body fat tissue, as evidenced by the reduction in BC change. This suggests that the lactation supplement, which contained protein of low rumen degradability, promoted a level of milk production that had to be supported by lipolytic activity. These cows also had the highest levels of plasma creatinine, the breakdown product of creatine phosphate, which is the energy store of muscle. Therefore, the body tissue breakdown was not just lipolysis, but also muscle tissue breakdown. The values for plasma creatinine were not abnormal, but the reference range (50–170 umol/L) is large. The supplement therefore stimulated milk yield, but the high level of body condition at calving prevented intake being increased to satisfy the demand for energy. The resulting rapid loss of body condition was substantial (1.5 units over the first 10 weeks), but was not sufficient to impair reproductive performance.
Only cows that had calved in the low BC increased intake in response to the protein supplement. The high-quality supplement could have enhanced rumen fiber digestion18 by increasing microbial growth, and hence allowed increased food intake. There was evidence for this in the reduced plasma urea N content, suggesting better utilization of rumen-degraded protein. These cows had the highest energy balances and intakes, including protein intakes, which could have been responsible for the increased milk protein concentration. The adequacy of dietary energy to meet requirements for milk production is indicated by the milk protein content, which was increased when the supplement was included in the diets of low BC cows but was decreased when the supplement was included in the diets of high BC cows.
Cows calving in high BC had no increase in intake with the supplement, which was probably because fat depots inhibit appetite physiologically, through insulin, growth hormone, prolactin, estrogens, and prostaglandins, and physically by restricting rumen volume.19 This apparent suppression of appetite in cows that calved in high BC and that were fed the supplement suggests that these cows did not feel excessively hungry. The increased plasma albumin concentration in cows in the lactation supplement treatment reflects the greater protein intake. The increase in UDP intake in cows receiving the lactation supplement increased milk protein output (from 434 g per day with supplement to 500 g per day without supplement, SED 29.7, P = 0.004). Elevated LDH in cows without the lactation supplement, particularly in cows that had been on the low BC treatment, indicates increased gluconeogenesis from lactate because of inadequate gluconeogenic substrates. LDH is a sensitive indicator of protein and energy malnutrition in humans.20 The elevated blood glucose concentration in these cows probably reflects a reduced glucose clearance rate. These cows apparently had a more balanced ruminal protein:energy ratio as indicated by reduced plasma urea concentrations.
The increase in social activity, particularly aggression, when the lactation supplement was fed requires further research before conclusions can be drawn in relation to welfare. It could derive from increased protein intake, because increased nitrogen status is correlated with aggressive behavior in field voles,21 and with brainstem auditory evoked responses22 and psychometric aptitude in humans.23 High-protein diets have also been found to increase aggression in monkeys,24 but decrease it in broilers.25 These apparently anomalous results could be because when food is the reward for aggression, animals on low-protein diets outcompete animals on high-protein diets, even though high-protein diets generally increase dominant–aggressive interactions.24 Tryptophan content of the supplement can be important as it is a precursor of the brain neurotransmitter serotonin. Fishmeal in particular has a high tryptophan content relative to most other feeds,23 and some studies suggest links with aggressive behavior.27,28
With regard to social behaviors, several studies have shown that protein malnutrition reduces social activity in mammals.29,30 This could be related to general health and vigor, but in cattle the observed effects of protein on social grooming and licking could also relate to coat condition, which is affected in many animals by protein nutrition.31,32
The experiment demonstrates the dominant effect of body condition at calving on the response to a feed supplement postpartum. The cows that were fed the low level of concentrate without a supplement during lactation did not lose the most body condition because they reduced their milk yield accordingly. The cows that were challenged to produce additional milk by a high-quality supplement during lactation had high levels of creatinine, indicating metabolism of body protein. A potentially useful indicator of protein/energy malnutrition was lactate dehydrogenase, which was reduced by feeding the lactation supplement. Furthermore, yield was only increased by supplements if there were sufficient body fat reserves at calving. The increase in aggressive and other interactions in cows fed the lactation supplement merits further research, but could relate to specific ingredients. There was no evidence from the cows’ production, physiology, or reproduction that feeding a low level of concentrates during lactation impaired welfare, because the cows reduced milk production accordingly.
The authors are grateful to the United Kingdom’s Ministry of Agriculture, Fisheries and Food for the provision of a postgraduate studentship for S. E. Kitwood, and to Colborn Dawes Nutrition for supply of the supplement.
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Table 1. Total Mixed Ration and Silage Chemical Composition for Treatments No Supplement and Supplement During the Lactation Period
Total mixed ration
supplement Supplement Silage
Forage DM: concentrate DM 77:23 69:31 –
DM (g/kg freshweight 270 283 240
pH ND ND 4.1
NH3 N (g/kg), total no. ND ND 137
Crude protein (g/kg DM) 135 161 135
Rumen undegraded protein (g/kg DM) 29 49 ND
Rumen degraded protein (g/kg DM) 107 112 ND
Modified ADF (g/kg DM) 290 277 301
Ash (g/kg DM) 67 69 53
Metabolizable energy (MJ/kg DM) 11.3 11.5 11.3
ND, not determined
Table 2. Intake, Production and Reproduction of Cows Fed to Achieve High and Low Body Condition Scores at Calving and Offered a Supplement or No Supplement After Calving
Transition Feeding High Low High Low SED1 Lactation Transition Interaction
Total DM intake (kg/d) 18.0 15.0 18.6 20.2 2.65 * NS *
Silage DM intake (kg/d) 14.6 12.4 14.3 15.5 1.50 NS NS *
Milk yield (kg/d) 15.4 17.3 21.3 16.7 1.81 * ** ***
Fat (g/kg) 37.2 36.8 36.1 36.0 1.82 NS NS NS
Protein (g/kg) 30.7 29.6 30.1 31.9 0.98 NS NS *
Lactose (g/kg) 46.5 47.1 46.4 47.2 1.07 NS NS NS
Liveweight change (kg/d) -0.66 -0.16 -0.78 -0.60 0.27 NS *** †
BC score change (units/wk) 0.02 -0.05 -0.07 0.00 0.043 NS *** **
Calving to 1st service (d) 53 50 51 60 11.0 NS NS NS
Calving to pregnancy (d) 85 88 71 79 15.0 NS NS NS
Services/pregnancy 1.8 2.2 1.7 1.6 – – – NS2
1Standard error of the difference between 2 means for the interaction between diet and BC.
2Analyzed by Chi square.
NS, not significant.
Table 3. Blood Serum Metabolites of Cows Fed to Achieve High and Low Body Condition Scores at Calving and Offered a Supplement or No Supplement After Calving
Lactation feeding No Supplement Supplement Significance of supplement Reference range
Transition feeding High Low High Low SED1 Lactation Transition Interaction for cattle
Glucose (mmol/L) 4.0 3.7 3.5 3.7 0.20 † NS NS 2.6-4.42
Urea N (mmol/L) 1.4 1.6 1.5 1.1 0.22 † NS ** 3.3-10.052
Creatinine (umol/L) 84.9 80.5 95.8 92.3 5.54 * NS NS 50-1702
Total protein (g/L) 72.5 72.1 71.0 76.8 2.85 NS NS NS 65-852
Albumin (g/L) 32.6 31.9 35.1 33.9 1.53 † NS NS 23-402
Globulin (g/L) 38.5 37.0 35.5 43.0 –3 NS NS * 32-452
Lactate dehydrogenase (IU/L) 1112 1246 1096 1052 78.0 † NS NS 700-14004, 0-19665
**P <0.01, *P <0.05, †P<0.10.
1 Standard error of the difference between 2 means for the interaction between diet and BC.
2 Determined by the Department of Clinical Veterinary Medicine, University of Cambridge.
3 Data not normally distributed, analysed by Kruskal-Wallis test.
5 Veterinary Laboratories Agency, Shrewbury (adjusted for temperature difference according to Kaneko.32).
NS, not significant.
Table 4. Behavior of Cows Offered No Supplement or a Supplement1 During Lactation
Behavior (incidents/cow/day) No supplement Supplement Significance
Standing-to-be mounted 0.7 1.0 NS
Attempted mounting 1.4 1.7 NS
Sniffing/licking 2.3 4.4 **
Aggression 3.1 6.5 ***
Grooming 1.1 2.6 ***
Chin rubbing 0.70 0.86 NS
There were no significant (P <0.10) effects of the transition period supplement and results are presented for the supplement treatments only.
**P <0.01, *P<0.05, †P<0.10.
NS, not significant.
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