Feed Intake Pattern Research Articles

Effect of type (barley vs. maize) and processing (grinding vs. dry rolling) of cereal on ruminal fermentation and microbiota of beef calves during the early fattening period

Ruminal acidosis is the most important nutritional disorder in intensively reared cattle and can be aggravated depending on the type of cereal in the concentrate and its processing, which affect the feed intake pattern and rumen fermentation and microbiota. Two compound feeds were formulated with a 0.60 mixture of maize and barley in proportions of 75:25 (M) and 25:75 (B), ground to 3.5mm (G) or dry-rolled (R). Eight 3-month old, rumen cannulated Holstein male calves were fed the experimental concentrates together with barley straw ad libitum, four of them receiving concentrate M and the other four receiving concentrate B throughout the experiment. Concentrates were offered to each animal in the two presentation forms in two 35-day periods, following a crossover arrangement. On days 33 and 35 of each period, rumen contents were sampled just before the morning feed distribution (8:30h) and 4 and 8h later to measure pH and determine volatile fatty acid (VFA), ammonia and lactic acid concentrations, as well as to characterise rumen bacterial community by qPCR. The pattern of feed intake was also monitored over the sampling days. The main cereal included in the concentrate scarcely affected ruminal fermentation. The higher fermentation rate of barley-based concentrates could be partly counterbalanced by a higher straw intake. Animals fed R cereals showed higher rumen pH (6.09 vs. 5.77, P<0.01) and lower lactic acid (72.5 vs. 95.2mg/L, P=0.065) and total VFA (110 vs. 138mmol/L, P<0.05) concentrations than those receiving G. This effect was in general more evident when maize was the major cereal in the concentrate, although the interaction of cereal type by processing form was not significant. Scarce effects on rumen microbiota were promoted by dietary factors; however, the low ruminal proportion of Streptococcus bovis observed regardless of the diet fed and rumen pH suggests that other microorganisms could be involved in the appearance of acidosis in beef cattle on high-grain diets. The more buffered rumen fermentation associated with dry-rolling processing could be partly due to its higher particle size, which reduces microbial and enzymatic access to the starch and its fermentation rate, at the same time as it promotes a more homogeneous pattern of intake throughout the day. Therefore, this processing method could be useful for preventing acidosis in beef calves at the outset of the fattening stage, especially when feeding maize-based diets.

Short communication: Effect of the feed presentation form on the intake pattern, productive traits and rumen pH of beef cattle fed high concentrate diets

Nutritional disorders like ruminal acidosis are common in Spanish beef production system, in which animals are fed diets with a high content in starch. This experiment studied the effect of feed presentation form (concentrate and straw offered separately, CD, or mixed in form of briquettes, BR) on the pattern of intake, growth and rumen pH of beef cattle fed high concentrate diets. The experiment was performed with 40 Holstein male calves, 32 of them for determining feed intake pattern and productive rates, and the remaining 8, which were previously provided with a ruminal cannula, to monitor rumen pH in two 21-day consecutive periods following a change-over design. Animals fed BR reduced feed intake rate during the first hour after feeding (18.6 vs. 24.0% of daily intake p&lt;0.001), but this diet promoted a lower rumen pH at all sampling times compared with CD (daily average of 5.98 vs. 6.33; p&lt;0.001) and tended to promote a lower total feed intake (7.08 vs. 9.77 kg DM/d; p&lt;0.001) and daily weight gain (1.43 vs. 1.76 kg/d; p=0.056). Offering the concentrate and the straw mixed in form of briquettes is not useful to prevent ruminal acidosis and improve growth, probably due to both a reduced particle size of straw and avoided self-regulation of straw intake along the day.

A modified sulphur hexafluoride tracer technique enables accurate determination of enteric methane emissions from ruminants

The sulphur hexafluoride (SF6) tracer technique enables determination of enteric methane emissions from large numbers of individual ruminant animals. The objective of this research was to identify and correct substantial errors within the SF6 technique. Six experiments were undertaken using respiration chamber, laboratory or SF6 techniques. Experiment 1 used respiration chambers to demonstrate that the daily pattern of methane emissions from dairy cows was related to their pattern of feed intake. In contrast, the daily emission of SF6 from these cows was constant and independent of the pattern of methane emission. This finding supports the contention that in order to accurately determine daily methane emissions using the SF6 technique, it is necessary that gases are collected continuously at a constant rate for 24h. Since development of the SF6 technique in 1993, it has been propounded that capillary-tube flow restrictors achieved a constant rate of sample collection into evacuated gas collection canisters. Laboratory experiments 2, 3, 4 and 5 demonstrated that, when capillary-tube flow restrictors are used, the rate of sample collection declined and caused a bias of up to 15.6% in calculated methane emissions. This error was caused by an interaction between the declining sample collection rate and the pattern of an animal's methane emission over 24h. In contrast, orifice plate flow restrictors maintained a constant sample collection rate at canister pressures <0.31atm and thereby minimised the decline in sample collection rate. Experiment 5 also demonstrated that sample collection using orifice plate flow restrictors, combined with initial (<0.03atm) and final (<0.49atm) canister pressures, substantially reduced measurement error. Accuracy of the modified SF6 technique, incorporating orifice plate flow restrictors for 24h sample collection, was validated in Experiment 6. The mean (S.D.) methane yield (g CH4/kg DMI) of eight cows did not differ (P=0.135) when determined using the modified SF6 technique 22.3 (1.44) or chambers 21.9 (1.65). In addition, the between-animal coefficient of variation for methane yield determined using the modified SF6 technique (6.5%) was similar to that determined using chambers (7.5%). Consequently the modified SF6 technique enables the statistical power of experiments to be increased or their size decreased. We conclude that the modified SF6 technique reduced error associated with SF6 release, sample collection and analysis. It is recommended that the modified SF6 technique should be used in preference to the original SF6 technique for determination of enteric methane emissions from ruminants.

English

Pineapple waste (PW) is a by-product from pineapple processing, mostly dumped to pollute the environment. This study was conducted to recycle PW by ensiling with maize cobs and brewer dried grains at different levels. Twelve (12) West African dwarf rams weighing between 15.00 to16.10 kg were randomly distributed into four diets. Diets included: 0, 20, 40 and 60% PW as diets 1, 2, 3 and 4, respectively. Parameters studied were feed intake, nutrient digestibility and fermentation patterns: total volatile fatty acids, lactic acid concentrations, rumen pH, ammonia nitrogen and nitrogen metabolism. Silage pH ranged from 3.60 to 6.40 in all treatments. Temperature of silages varied from 31.10 to 31.50&deg;C. CP, NDF and ADF ranges were: 12.15 to 13.74, 40.61 to 47.20 and 20.62 to 28.58%, respectively. Body weight intake, faecal output, crude protein intake, crude fibre intake, ether extract intake and ash-intake at 20% inclusion level were: 525.69, 73.27, 72.76, 26.63 and 31.17g/day, respectively. Highest total volatile fatty acid of 56.18 mg/dl was observed in 20% inclusion level. CP digestibility decreased linearly as the protein contents of the diets increased. Therefore, PW can be preserved for a longer period and utilized by ruminants at 20% PW inclusion rate. &nbsp; Key words: Pineapple waste, silage, intake, digestibility, sheep.

Feed intake of sheep when allowed ad libitum access to feed in methane respiration chambers

The patterns of feed intake when animals are allowed ad libitum access to feed in a respiration chamber is not known, nor are the potential effects of the artificial environment of chambers on voluntary feed intake. The objectives of the study were to describe the pattern of hourly feed intake of sheep when fed for ad libitum intake in respiration chambers and determine the repeatability of this pattern and the correlation between feed intake and methane production calculated at hourly intervals. Daily and hourly measurements of methane production and feed intake of 47 Merino wethers were measured in respiration chambers twice, 4 wk apart. We found that hourly feed intake of sheep with ad libitum access to feed in respiration chambers showed a repeatable pattern over the 2 measurement periods (r = 0.89, P < 0.001). During both measurements, sheep ate continuously throughout the 23 h period, but most of the eating occurred during the first 8 h in the respiration chambers. There was a significant linear correlation (r = 0.22) between hourly feed intake and hourly methane production (P < 0.001). An unexpected result from this study was that despite using an accepted and published acclimatization procedure to habituate the animals to the respiration chambers, sheep had 15 to 25% lower feed intake in the respiration chambers compared with their feed intake during the previous week in the animal house pens. In addition, daily feed intake in the respiration chamber was not correlated with feed intake in any of the 7 d before entering the chamber (P > 0.05). Future methane research may consider using feed intake and changes in intake levels as a quantitative indicator of habituation to the methane measurement procedure and environment, which, given the tight association between feed intake and methane production, will be crucial in providing accurate values for methane production.

Meal pattern analysis for effects of compound feed formulation in mid to late lactating dairy cows fed hay and compound feed both ad libitum

The Kempen System is a dairy feeding system allowing ad libitum access to pelleted compound feed (CF) and hay. This system allows high DM intake (DMI) up to 30 kg DM (80% CF), but small and frequent CF meals are essential to reduce negative ruminal pH fluctuations. Little is known about feed intake patterns of cows on ad libitum and separated access to CF and hay. Meal pattern analysis was performed to evaluate feed intake behaviour of two different isoenergetic and isonitrogenous CF (starch vs fibre), contrasting in neutral detergent fibre, acid detergent fibre and starch content. Twenty primi- and multiparous Holstein-Friesian cows (203 ± 35.4 days in milk) received grass hay ad libitum with one of the two CF also offered ad libitum. Meal criteria, the shortest non-feeding interval between feeding events separating two consecutive meals, were used to cluster feeding events into separate meals. The meal criteria were determined per cow by fitting the log10-transformed feeding intervals to Gaussian–Gaussian probability density functions. The DMI of CF fibre (18.8 ± 0.54 kg) tended to be greater (P = 0.09) than starch (18.1 ± 0.54 kg/day), while that of grass hay (4.8 ± 0.29 kg) was unaffected (P = 0.23). The CF meal size did not differ (P = 0.26) between treatments (starch 2.9 vs fibre 3.0 ± 0.11 kg/meal), but number of meals per day (6.36 ± 0.229, P = 0.87) and meal durations (64 ± 3.5 min, P = 0.87) did not differ between treatments. The differences in CF formulation were insufficient to create detectable differences in feed intake nor intake behaviour patterns.

Effects of alginate and resistant starch on feeding patterns, behaviour and performance in ad libitum-fed growing pigs

This study assessed the long-term effects of feeding diets containing either a gelling fibre (alginate (ALG)), or a fermentable fibre (resistant starch (RS)), or both, on feeding patterns, behaviour and growth performance of growing pigs fed ad libitum for 12 weeks. The experiment was set up as a 2×2 factorial arrangement: inclusion of ALG (yes or no) and inclusion of RS (yes or no) in the control diet, resulting in four dietary treatments, that is, ALG−RS− (control), ALG+RS−, ALG−RS+, and ALG+RS+. Both ALG and RS were exchanged for pregelatinized potato starch. A total of 240 pigs in 40 pens were used. From all visits to an electronic feeding station, feed intake and detailed feeding patterns were calculated. Apparent total tract digestibility of energy, dry matter (DM), and CP was determined in week 6. Pigs’ postures and behaviours were scored from live observations in weeks 7 and 12. Dietary treatments did not affect final BW and average daily gain (ADG). ALG reduced energy and DM digestibility (P<0.01). Moreover, ALG increased average daily DM intake, and reduced backfat thickness and carcass gain : digestible energy (DE) intake (P<0.05). RS increased feed intake per meal, meal duration (P<0.05) and inter-meal intervals (P=0.05), and reduced the number of meals per day (P<0.01), but did not affect daily DM intake. Moreover, RS reduced energy, DM and CP digestibility (P<0.01). Average daily DE intake was reduced (P<0.05), and gain : DE intake tended to be increased (P=0.07), whereas carcass gain : DE intake was not affected by RS. In week 12, ALG+RS− increased standing and walking, aggressive, feeder-directed, and drinking behaviours compared with ALG+RS+ (ALG×RS interaction, P<0.05), with ALG−RS− and ALG−RS+ in between. No other ALG×RS interactions were found. In conclusion, pigs fed ALG compensated for the reduced dietary DE content by increasing their feed intake, achieving similar DE intake and ADG as control pigs. Backfat thickness and carcass efficiency were reduced in pigs fed ALG, which also showed increased physical activity. Pigs fed RS changed feeding patterns, but did not increase their feed intake. Despite a lower DE intake, pigs fed RS achieved similar ADG as control pigs by increasing efficiency in DE use. This indicates that the energy utilization of RS in pigs with ad libitum access to feed is close to that of enzymatically digestible starch.

Feeding behaviour in dairy cows with and without the influence of clinical diseases or subclinical disorders

Abstract. The objective of this study was to describe and compare circadian pattern of feed intake and feeding behaviour in healthy and diseased dairy cows. Test animals (n=138) were separated into two groups according to their health status. Health and management data were used to exclude cows with clinical or subclinical diseases. Fifteen cows of the test herd complied with the defined criteria and formed the reference group »healthy«. The behaviour of the remaining 123 cows was compared with the reference group. Both groups were used to analyse the feed intake and feeding behaviour on a daily base and in the course of 24 h. During a defined time range from day 28 post-partum to day 56 post-partum behavioural differences within these groups were analysed. There were no significant differences in daily feed intake (40.7 vs. 41.9 kg fresh matter per day, P=0.42). However, feeding behaviour pattern differed between the two groups (daily feeder visits, daily feeding time, number of daily feeder visit, number of daily meals, meal duration, feeding time within a meal, feeder visits per meal). For example, average feeder visit was shorter in the group with subclinical/ clinical health disorders than in the reference group (7.2 vs. 8.1 min, P=0.024). Differences in circadian feeding behaviour could be detected by analysing the feed intake and feeding time over the course of the day. Linear regression analyses showed strong correlations between feeding time and feed intake on hourly base (R² = 0.8) and on daily base (R² = 0.7).

Prenatal developmental toxicity study of n-heneicosane in Wistar rats

n-Heneicosane (C21) is one of the vital pheromone for attracting mosquitoes of Aedes spp to lay their eggs in areas of stagnant fresh water, for their subsequent destruction, thus controlling spread of dangerous disease transmission by the vectors. As part of a safety evaluation, we have investigated embryo toxic and teratogenic potential, if any, of C21 following OECD Test Guideline 414. C21 was offered at a dose of 1 g/kg body weight mixed in the standard rat pellet diet to treated rats, whereas the control group received only standard rat pellet diet. There were no mortalities and animals did not show any clinical signs of toxicity. A similar pattern of body weight gain, feed and water intake was observed in treated and control groups. Analysis of maternal toxic response, maternal end points of development of the foetus and developmental end points for litters did not show any gross structural abnormality in dams or foetus of treated group compared to that of the control group. Thus, it was concluded that C21 at a dose of 1 g/kg was neither embryo toxic nor teratogenic in Wister rats. Furthermore, the no observed adverse effect level for teratogenicity for C21 in rats may be considered as 1 g/kg body weight under the present experimental conditions.

Development of appropriate fibrolytic enzyme combination for maize stover and its effect on rumen fermentation in sheep.

In vitro studies were undertaken to develop an appropriate fibrolytic enzymes cocktail comprising of cellulase, xylanase and β-D-glucanase for maize stover with an aim to increase its nutrient utilization in sheep. Cellulase and xylanase added individually to ground maize stover at an increasing dose rates (0, 100, 200, 400, 800, 1,600, 3,200, 6,400, 12,800, 25,600, 32,000, 38,400, and 44,800 IU/g DM), increased (p<0.01) the in vitro dry matter digestibility and in vitro sugar release. The doses selected for studying the combination effect of enzymes were 6,400 to 32,000 IU/g of cellulase and 12,800 to 44,800 IU/g of xylanase. At cellulase concentration of 6,400 IU/g, IVDMD % was higher (p<0.01) at higher xylanase doses (25,600 to 44,800 IU/g). While at cellulase doses (12,800 to 32,000 IU/g), IVDMD % was higher at lower xylanase doses (12,800 and 25,600 IU/g) compared to higher xylanase doses (32,000 to 44,800 IU/g). At cellulase concentration of the 6,400 to 32,000 IU/g, the amount of sugar released increased (p<0.01) with increasing levels of xylanase concentrations except for the concentration of 44,800 IU/g. No effect of β-D-glucanase (100 to 300 IU/g) was observed at lower cellulase-xylanase dose (cellulase-xylanase 12,800 to 12,800 IU/g). Based on the IVDMD, the enzyme combination cellulase-xylanase 12,800 to 12,800 IU/g was selected to study its effect on feed intake and rumen fermentation pattern, conducted on 12 rams (6 to 8 months; 20.34±2.369 kg body weight) fed 50% maize stover based TMR. The total volatile fatty acids (p<0.01) and ammonia-N concentration was higher in enzyme supplemented group, while no effect was observed on dry matter intake, ruminal pH and total nitrogen concentration.

Effect of compound feed pelleting and die diameter on rumen fermentation in beef cattle fed high concentrate diets

The effect of feeding a compound feed as meal (M) or pelleted at 3.5 (P3.5) or 10 (P10) mm i.d. on feed intake pattern and rumen fermentation in growing calves was investigated. Compound feeds were fed ad libitum with barley straw to six 3-mo-old rumen cannulated calves in a double 3×3 Latin square arrangement. In a first 9-wk phase (I) free access to concentrate was allowed, whereas in a second 6-wk phase (II) access was restricted to 09:00h to 11:30h and 17:00h to 19:30h. Rumen samples were collected on two non-consecutive days at 08:30h, 13:00h and 17:00h. Pelleting increased the degree of starch gelatinization from 0.113 in M to 0.205 and 0.154, in P3.5 and P10. In both phases, P10 slowed consumption of concentrate during morning feeding (P<0.01), although treatments did not affect total daily concentrate intake (97gDM/kgLW0.75 and 82gDM/kgLW0.75) in phases I and II. In phase I, pH before morning distribution was lower than in phase II (6.5 versus 7.2). Four hours after feeding, there was a pH drop (P<0.001), which was higher in phase II (1.5 units) than in phase I (0.7 units), in line with a higher concentrate intake (4.10kg versus 1.89kg). Calves fed P3.5 tended (P=0.052) to a lower pH than those on M in phase I, and those fed P10 had the least decrease in pH after feeding. No pH differences occurred between treatments in phase II, although pH recovery from 4 to 8h after feeding tended to be more (P=0.073) for P10. Rumen lactic acid concentration increased after feeding (P<0.05 and P<0.001) in phases I and II, reaching 45.7mg/l and 39.6mg/l, respectively. In phase II, P3.5 animals reached a higher (P<0.01) concentration than M and P10 animals. Rumen ammonia concentration decreased (P<0.001) after feeding, reaching the lowest values 4h later (23.3mg/l and 13.6mg/l in phases I and II). P3.5 showed lower ammonia concentration than M in phase I (P<0.05). Total volatile fatty acid (VFA) concentration increased (P<0.001) after feeding in both phases, decreasing the acetic to propionic ratio (P<0.001). In phase I, calves fed M tended (P=0.074) to have lower total VFA rumen concentration and higher acetic to propionic ratio (P<0.01) than those fed pellets. Results suggest that with pelleting at 3.5mm, increased ruminal fermentation rate dominates regulation of substrate delivery and results in lower pH values that could eventually translate into higher risk of acidosis compared with unprocessed meal. Increasing the pellet diameter to 10mm may decrease the rate of fermentation through a homogeneous daily intake pattern, without affecting total intake, even under conditions of restricted feeding.

Time of feed provision (21:00 vs. 09:00 h) orchestrates postprandial rhythms of food intake and peripheral glucose in lactating cows

The objective of the first experiment was to determine the effects of feeding time and dietary forage to concentrate ratio on postprandial rhythms of feed intake and peripheral blood glucose (BG). Four multiparous (83 days in milk) and four primiparous (81 days in milk) Holstein cows in a 4 × 4 Latin square design study were fed either a higher concentrate (HC, forage to concentrate ratio = 38.5:61.5) or a lower concentrate (LC, forage to concentrate ratio = 50.6:49.4) total mixed ration (TMR) at either 21:00 h or 09:00 h. The study had four 21-d periods, each with 14-d adaptation. Jugular blood was sampled every 2-h for two 24-h periods during sampling weeks. Feeding at 21:00 h vs. 09:00 h increased the eating rate, and thus, increased feed intake within 3 h of feeding from 26% to 37% of total daily intake. BG exhibited significant postprandial rhythms that were altered by feeding time. BG showed a marked decline shortly pre- and post-feeding in evening-fed cows but not in morning-fed cows. Feeding HC vs. LC diet increased the BG. The objective of the second experiment was to establish postprandial BG responses to feeding time in lactating cows after 28-d adaptation periods. Four multiparous and four primiparous lactating Holstein cows (82 days in milk) were used in a cross-over design study with two six‐week periods. Each period had four weeks of adaptation. A TMR with 49.8% concentrate was fed at either 09:00 or 21:00 h to permit 5–10% feed refusals. Jugular blood was sampled via catheters every 2 h for two 24-h periods during week-5 of each period. Evening vs. morning feeding increased feed intake within 3-h of feed delivery (55% vs. 46% of daily intake). BG exhibited marked declines at 2 h pre- and post-feeding in cows fed at 21:00 h vs. 09:00 h. Time of feeding did not affect daily averages of BG in any of the experiments. The results establish TF as a determinant of postprandial and diurnal patterns of feed intake and BG in once-daily fed lactating dairy cows. TF can therefore affect splanchnic and peripheral energy metabolism and efficiency in lactating cows. Considering the comparative nature of the splanchnic metabolism for optimal mechanistic understanding of the gut function in any given species, the findings serve as a metabolic model for high-producing ruminants and humans.

The effect of immunization against GnRF on nutrient requirements of male pigs: a review

In most countries, male pigs are physically castrated soon after birth to reduce the risk of boar taint and to avoid behaviours such as fighting and mounting. However, entire male pigs are more feed efficient and deposit less fat than barrows. In addition, many animal welfare organizations are lobbying for a cessation of castration, with a likelihood that this could lead to inferior pork unless an alternative method is used to control boar taint. An alternative to physical castration is immunization against gonadotrophin releasing factor (GnRF) which allows producers to capitalize on the superior feed efficiency and carcass characteristics of boars without the risk of boar taint. From a physiological perspective, immunized pigs are entire males until shortly after the second dose, typically given 4 to 6 weeks before slaughter. Following full immunization, there is a temporary suppression of testicular function and a hormonal status that resembles that of a barrow. Nutrient requirements will be different in these two phases, before and after full immunization. Given that there have been few published studies comparing the lysine requirements of entire males and barrows in contemporary genotypes, it is useful to use gilt requirements as a benchmark. A series of meta-analyses comparing anti-GnRF immunized boars and physical castrates and use of nutritional models suggest that the lysine requirement of entire males before the second immunization is 5% higher than for gilts, from 25 to 50 kg BW, and by 8% from 50 to 95 kg. Given that the penalty in growth performance for having inadequate dietary lysine is greater in males than in gilts or barrows, it is important to ensure that lysine requirements are met to obtain the maximum benefits of entire male production during this phase. After the second immunization, the lysine requirement of immunized males decreases and may become more like that of barrows. In addition, a consistent effect of full immunization is a marked increase in voluntary feed intake from about 10 days after the second dose. Putting these together, the estimated lysine requirement, expressed in terms of diet composition, falls to 94% of the gilt level. Although general principles can be described now, further research is needed to fully define the lysine requirements of immunized boars. It is important that the temporal pattern of tissue deposition rates and feed intake be explored to be incorporated into models to predict nutrient requirements over the period of rapidly changing metabolism.

Feeding behaviors of transition dairy cows fed glycerol as a replacement for corn

Feed sorting is a natural behavior of dairy cows that can result in inconsistencies in the nutritive value of a total mixed ration (TMR). The objective of this study was to determine the effects of replacing high-moisture corn with glycerol on feed sorting and the feed intake pattern of transition dairy cows. Multiparous Holstein cows (n=26) were paired by expected calving date, housed in individual tie stalls, and fed diets containing either glycerol or high-moisture corn once daily from d −28 to +56 relative to calving. Glycerol was included at 11.5 and 10.8% of the ration dry matter for the pre- and postpartum diets, respectively. The feed consumption pattern was determined by measuring TMR disappearance during the intervals from 0 to 4h, 4 to 8h, 8 to 12h, and 12 to 24h relative to feed delivery. Feed sorting was determined on d −16, −9, 9, 16, and 51 relative to calving at 4, 8, 12 and 24h after feeding. The TMR particle size profile was determined at feed delivery and at 4, 8, 12, and 24 after feed delivery by using the Penn State Particle Separator (Nasco, Fort Atkinson, WI) to yield long (>19mm), medium (<19mm, >8mm), short (<8mm, >1.18mm), and fine (<1.18mm) particles. Overall feed intake did not differ between diets and was 14.7±0.4 and 20.2±0.5 kg/d for the pre- and postpartum intervals, respectively. During the prepartum period, glycerol decreased the amount of feed consumed during the first 4h after feed delivery (7.22 vs. 5.59±0.35 kg; control vs. glycerol, respectively) but increased feed consumed from 12 through 24h after feed delivery (2.22 vs. 3.82±0.35 kg; control vs. glycerol, respectively). Similar effects on the feed consumption pattern were observed after calving. During the prepartum period, cows fed the control diet sorted against long particles, whereas cows fed glycerol did not sort against long particles (77.2 vs. 101.5±3.50% of expected intake for control vs. glycerol; significant treatment effect). The data indicate that addition of glycerol to the TMR alters the feed consumption pattern to increase feed consumption late in the day at the expense of feed consumed immediately after feeding, and it reduces sorting behavior against long particles. Together, these may reduce diurnal variations in the rumen environment to promote greater rumen health in transition cows.

Postprandial rhythms of circulating urea in lactating dairy cows: feeding timing and diet effects

The objective of the first experiment was to determine effects of feeding time and dietary forage to concentrate ratio on diurnal averages and rhythms of blood urea (BU). Four multiparous (body weight, BW = 652 ± 14 kg, mean ± SD; body condition score, BCS = 2.87 ± 0.14; days in milk, DIM = 83 ± 22) and four primiparous (BW = 667 ± 110 kg; BCS = 3.19 ± 0.66; DIM = 81 ± 23) Holstein cows were utilized in a 4 × 4 Latin square design study with a 2 × 2 factorial arrangement of feeding time and diet type. A higher concentrate (forage to concentrate ratio = 38.5:61.5) or a lower concentrate (forage to concentrate ratio = 50.6:49.4) total mixed ration (TMR) was offered at either 2100 h or 0900 h. The study had four 21-d periods, with 14 d of adaptation. Blood was sampled every 2 h for two 24-h periods during sampling weeks. Feeding at 2100 h vs. 0900 h increased feed consumed within 3 h of feeding time, from 26% to 37% of total daily intake. Total daily dry matter intake (DMI) was similar among treatments. BU exhibited significant diurnal rhythms in both groups, which depended on diet type and its interactions with sampling hour and time of feeding (TF). The objective of the second experiment was to establish diurnal and post-feeding responses in BU levels to feeding time in lactating cows following 28-d adaptation periods. Four multiparous and four primiparous lactating Holstein cows (82 DIM) were used in a cross-over design study with two 6-wk periods. Each period had 4 wk of adaptation. A TMR with 49.8% concentrate was offered at either 0900 or 2100 h to permit 5–10% feed refusals. Jugular blood was sampled via catheters every 2 h for two 24-h period during wk 5 of each period. The proportion of daily TMR intake consumed within 3 h of feeding time was 55% in cows fed at 2100 h, and 46% in cows fed at 0900 h (P < 0.05). Rumen ammonia was higher at 2 h but lower at 6 h post-feeding and remained lower between 6 and 20 h post-feeding in cows fed at 2100 h vs. 0900 h. Feeding time did not affect daily averages of BU. BU increased shortly after feeding in morning-fed cows but not in evening-fed cows. BU was higher for about 12 h pre-feeding in evening- vs. morning-fed cows. Results establish that TF alters postprandial and diurnal patterns of feed intake, rumen ammonia, and peripheral BU. Time of eating and its interaction with diet type can therefore affect splanchnic and peripheral nitrogen metabolism and efficiency in lactating cows. Considering the comparative nature of the splanchnic metabolism in optimal mechanistic understanding of the gut function in any given species, these data could serve as a theoretical and in several aspects as an applied metabolic model for other high-producing ruminants and humans.

Ruminant chronophysiological management: an emerging bioscience

The objective of this paper is to introduce, discuss, and delineate an emerging bioscience known as chronophysiological management. Most recent research discov- eries have promised physiological innovations in laboratory animals, humans, and livestock. Lactating ruminants have high intake and production levels above maintenance, and thus are exceptional models for studying evolutionary nutrition and physiology. The evolution of animals has led to specialized behaviors that involve mainly overnight rumination and primary daytime (sunrise and sunset) grazing and eating. Consequently, eating activity, rumen ecology, postrumen nutrient assimilation, and peripheral nutrient metabolism have developed unique diurnal and nocturnal rhythms. These physiological rhythms are known as circadian rhythms that lead animal endocrinology and metabolism. Most recent findings demonstrate that altering feeding timing alters postprandial patterns of feed intake, rumen fermentation, and peripheral metabolism in both intensively housed and grazing lactating cows. Evening instead of morning feeding has improved milk and milk energy production. These demonstrations contribute to creating an evolutionary bioscience that links animal nutritional and physiology to chronobiology. The emerging bioscience of ruminant chronophysiological management is the incorporation of chronophysiology into livestock practices. Different species will have their own special response to altered chronophysiological management. Such post- modern strategies will therefore be an interface of ruminant, nonruminant, and human ecologies.

Morning vs. evening feed delivery for lactating dairy cows

Nikkhah, A., Furedi, C. J., Kennedy, A. D., Scott, S. L., Wittenberg, K. M. Crow, G. H. and Plaizier, J. C. 2011. Morning vs. evening feed delivery for lactating dairy cows. Can. J. Anim. Sci. 91: 113–122. A study was conducted to investigate the effects of changing feed delivery time from morning (0900) to evening (2100) on feed intake, diurnal feed intake patterns, digestion, rumen fermentation, milk production and composition, as well as on several blood metabolites. Eight (four ruminally cannulated) lactating Holstein cows, consisting of four primiparous and four multiparous cows, were used in the study. The change in the time of feed delivery increased the proportion of feed consumed within 3 h of feed delivery in all cows (54.7 vs. 46.3±4.1%, means±SE, P=0.05), but increased daily dry matter intake only in primiparous cows (18.5 vs. 20.4±0.7 kg d−1, P=0.05). Average daily concentrations of blood glucose, lactate, urea and β-hydroxybutyrate (BHBA) as well as rumen pH and concentrations of volatile fatty acids (VFA) were not affected by feed delivery time. However, rumen pH was lower (P&lt;0.05), at 5 and 6 h after feed delivery, while total rumen VFA and acetate were higher (P&lt;0.05) only at 6 h after feed delivery in cows fed in the evening. Also, compared with feed delivery at 0900, feeding cows at 2100 resulted in lower (P&lt;0.05) blood glucose and urea at 2 h after feed delivery, and increased BHBA (P&lt;0.05) at 4 and 6 h after feed delivery. Cows fed at 2100 tended to produce more milk fat than those fed at 0900 (1.11 vs. 0.97±0.07 kg d−1, P=0.08). Milk yield and milk protein were not affected by the time of feed delivery. Changing the feed delivery time from morning to evening increased apparent total tract digestibility of dry matter, nitrogen, and neutral detergent fibre. The results of this study suggest that changing time of feed delivery from 0900 to 2100 increases feed consumption within 3 h after this delivery and rumen fermentation within 6 h after this delivery, changes diurnal patterns of glucose, urea and BHBA in peripheral blood, tends to increase milk fat, and increases nutrient digestibilities.

Performance, ruminal changes, behaviour and welfare of growing heifers fed a concentrate diet with or without barley straw

Two experiments were conducted to ascertain the effects of feeding an all-concentrate diet to growing heifers on performance, ruminal fermentation, behaviour and welfare. In experiment 1, eight tethered rumen fistulated Holstein heifers (143 ± 8.7 kg, initial BW) were used to study the effects of treatment on intake, ruminal changes and behaviour. In experiment 2, 48 Friesian female calves (initial BW = 84.5 ± 1.37 kg) were used to study the effects of treatment on performance, behaviour and welfare in feedlot conditions. In both experiments, treatments consisted of concentrate with barley straw (BS) or without barley straw (NBS) and feed was offered at 0830 h on an ad libitum basis. Experiment 1 was performed in four 42-day periods, and sampling was carried out in the last week of each period. Ruminal samples were collected over 3 days at 0, 4, 8 and 12 h post-feeding to measure pH, and volatile fatty acids (VFA) and NH3-N concentrations. Maintenance behaviour was video-recorded for 24 h over three consecutive days of each experimental period and feed intake pattern was studied by means of feed bunks mounted on digital platform scales. There were no statistical differences in average daily gain (ADG), concentrate dry matter (DM) intake or CP intake. In contrast, NDF intake and ADF intake were greater in heifers fed BS than NBS. Average ruminal pH was lower, whereas total VFA was greater, in heifers fed NBS diet. There were no differences in NH3-N, and in d- and l-lactate concentrations. Time spent in ruminating was shorter, and stereotypies were more frequent in heifers fed diet NBS compared with those fed BS. In experiment 2, nine 28-day periods were established, in which DM intake and ADG were measured, blood and faecal samples were taken for haptoglobin and glucocorticoid metabolites determination, respectively, as welfare indicators, and behaviour was monitored by video recording. Concentrate intake was similar in both treatments, but total feed intake was greater in heifers fed BS diet. As there were no differences in ADG between treatments, gain efficiency was lower in those fed BS than those fed NBS. Blood haptoglobin and faecal glucocorticoids metabolites were not different between treatments. In these competitive conditions, rumination was also reduced and stereotypic behaviour increased by straw exclusion. In conclusion, performance was either not affected or improved by straw exclusion, but animal behaviour was affected, suggesting a negative effect on animal welfare.

Effect of selection for residual feed intake on feeding behavior and daily feed intake patterns in Yorkshire swine1

Residual feed intake (RFI) is a measure of feed efficiency defined as the difference between observed and predicted feed intake based on average requirements for growth and maintenance. The objective of this study was to evaluate the effect of selection for decreased RFI on feeding behavior traits and to estimate their relationships with RFI. Three data sets from the 4th and 5th generations of a selection experiment with a line selected for reduced RFI (LRFI) and a randomly selected control line (CTRL) were analyzed. Lines were mixed in pens of 16 and evaluated for feeding behavior traits obtained from a single-space electronic feeder over a growing period of ~3 mo before ~115 kg. The following traits were evaluated as averages over the entire test period and over the first and second half of the test period: number of visits per day and hour; occupation time per day, visit, and hour; feed intake (FI) per day, visit, and hour; and FI rate per visit. Models used included fixed effects of line and feeder, covariates of on-test age and FI per day, and random effects of pen, on-test group, sire, and litter. Repeated measures models were used to analyze feeding patterns during the day. The LRFI pigs had significantly less FI per day than CTRL pigs for all 3 data sets. With adjustment for FI per day, line differences of all traits were in the same direction for all 3 data sets but differed in significance and size. Feed intake per visit and hour and visits per day and hour did not differ between lines, but the trend was for LRFI pigs to have fewer visits, in particular during peak eating times. The LRFI pigs had a greater feeding rate and less occupation time per day, visit, and hour than CTRL pigs, but this was not significant for all data sets. Correlations of RFI with FI per day and visit and visits per day were positive. Average daily gain was positively correlated with FI per day and visit and occupation time per visit but negatively correlated with visits per day. Feed intake per day was positively correlated with backfat. In conclusion, feed efficiency may be affected by FI behavior because selection for decreased RFI has resulted in pigs that spend less time eating and eat faster.

Effects of a Stair-step Growth Pattern on Improvements in Meat Quality and Growth in Hanwoo Steers

The present study was conducted to examine the effect of a stair-stepped feed intake pattern on growth, feed efficiency, and meat quality or Hanwoo steers. Twenty-seven 11-month-old Hanwoo steers were randomly divided into mree groups. The control group was fed according to the Korean steer feeding program, and the other two groups were fed according to an alternated feeding schedule of 3-2-4-2 months. During the first three months of the experiment, treatment group 1 (T1) and treatment group 2 (T2) were fed 20% and 30% less than the control group, respectively. For the following two months, the T1 group was fed 20% more than the control group while the T2 group was fed 20% less than the control group. In the third step, T1 and T2 groups were fed 20% and 10% less, respectively, than the control group for four months. In the last two months, T1 and T2 groups were fed 20% more than the control group. After the stair-step feeding trial, steers were fed concentrated feed ad libitum for five months. The altered feed intake pattern did not affect daily body weight gain. However, daily feed intake tended to decrease and growth efficiency tended to increase in the two treatment groups compared to the control group. Altered feed intake also affected blood metabolite levels. The serum glucose and BUN level of the T1 group increased in the first re-fed period compared to the T2 and control groups. The serum cholesterol level of the T2 group decreased in the first restricted-re-fed growth period compared to the T1 and control groups. The serum NEFA levels of the two treatment groups increased from the first restricted period compared to the controls. The serum insulin level of the T2 group increased in the last period compared to the T1 and control groups. Regarding meat yield index, the control group was significantly higher than the T2 group (p<0.05). Regarding meat yield grade, the carcass back fat thickness of the T2 group was significantly higher than the control group (p<0.05). In marbling score, the T1 group was the highest (4.9), followed by the control group (4.1) and the T2 group (4.0). These results indicate that using a stair-stepped growth pattern (T1) can contribute to improvements in growth efficiency and muscle marbling.