Glycogen metabolism and ultimate pH of muscle in Merino, first-cross, and second-cross wether lambs as affected by stress before slaughter

1999 ◽  
Vol 50 (2) ◽  
pp. 175 ◽  
Author(s):  
G. E. Gardner ◽  
L. Kennedy ◽  
J. T. B. Milton ◽  
D. W. Pethick

This experiment compared the metabolism of muscle glycogen and the ultimate pH (pHu) of muscle in Merino and crossbred lambs fed the same diet but subjected to different levels of stress pre-slaughter. Twenty- five Merino, 24 first-cross (Merino dam × Poll Dorset sire), and 23 second-cross (Border Leicester × Merino dam and Poll Dorset sire) wether lambs (6 months old, 30 kg liveweight) were maintained for 8 weeks on a complete pelleted diet based on lupin seed, straw, and barley grain (metabolisable energy, 10.8 MJ/kg; protein, 17.4% in dry matter), with a feed intake of 1.3 kg dry matter /day for each breed. At Week 6, muscle biopsies were taken from 15 lambs of each breed, and at Week 8, 5 animals from each breed were slaughtered at an experimental abattoir 10 min after removal from their pens (low pre-slaughter stress). The remaining lambs, separated into breeds, were transported for 2 h and slaughtered after 24 h lairage at a commercial abattoir. Muscle samples were taken at slaughter, and assayed with the biopsy samples for glycogen concentration (corrected for lactate concentration), myoglobin concentration, and citrate synthase activity. The pHu of muscle was measured 48 h post slaughter. Compared with commercially slaughtered lambs, the muscle tissues of lambs subjected to low pre-slaughter stress had higher glycogen concentrations post mortem, lower pHu, and no significant loss of glycogen between pen and slaughter. Breed had no effect on glycogen, pH, or the colour of muscle under low-stress slaughter conditions or when the muscle biopsy was taken. In contrast, breed had a significant influence under commercial slaughter conditions, the muscle of Merino lambs having the lowest glycogen concentration post portem, and the highest pHu and loss of glycogen between pen and slaughter. Irrespective of stress, second-cross lambs had higher myoglobin concentrations and citrate synthase activities than the Merino lambs, indicating greater pigmentation of muscle in the second-cross animals. We conclude that higher proportions of Merino genes are associated with a greater sensitivity to stress in lambs destined for slaughter.

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 175-175
Author(s):  
Élisabeth Chassé ◽  
Frédéric Guay ◽  
Marie-Pierre Létourneau-Montminy

Abstract This study was conducted to determine the effect of pelleting on the digestibility of corn-soybean meal-based diet in growing pigs. Two trials with 6 pigs cannulated at the distal ileum were conducted. In each trial, pigs were assigned to each treatment following a crossover design. In each experiment, the same diet, composed of corn and soybean meal with 10% wheat from two different feed mills, was served in pellet or mash form. Pelleting allowed an increase in digestibility in one of the trials. Apparent ileal digestibility (AID) of dry matter (DM), crude protein (CP) and digestible energy (DE) were improved with pelleting by 8, 12 and 9% (P< 0.01). The AID of amino acids (AA) was also improved (P< 0.05). Apparent total tract digestibility (ATTD) was increased by pelleting in DM, CP and DE by 5, 7 and 6% respectively (P< 0.01). The digestibility of the mash diet in experiment 1 was lower than in the pelleted diet in the experiment 1 and both diets in experiment 2 as shown by the interaction Pelleting X Trial which was significant for the AID and ATTD of DM, CP and DE (P< 0.01). Therefore, in experiment 1, pelleting allows to improve the digestibility of diet to the same level as in experiment 2. The AID of CP was higher by 37% in the mash diet from the second experiment compared to the one in the first experiment. Even though the same ingredients were chosen in the two experiments, this shows the variability in digestibility existing between different feed mills and ingredient sources. This difference was not observed in pelleted diets. The results obtained in these two trials show that pelleting can reduce the variability of digestibility and then give a good digestibility of diets even if the ingredients are of different quality or sources.


1996 ◽  
Vol 270 (2) ◽  
pp. E328-E335 ◽  
Author(s):  
A. Chesley ◽  
G. J. Heigenhauser ◽  
L. L. Spriet

The purpose of this study was to examine the regulation (hormonal, substrate, and allosteric) of muscle glycogen phosphorylase (Phos) activity and glycogenolysis after short-term endurance training. Eight untrained males completed 6 days of cycle exercise (2 h/day) at 65% of maximal O2 uptake (Vo2max). Before and after training subjects cycled for 15 min at 80% of Vo2max, and muscle biopsies and blood samples were obtained at 0 and 30 s, 7.5 and 15 min, and 0, 5, 10, and 15 min of exercise. Vo2max was unchanged with training but citrate synthase (CS) activity increased by 20%. Muscle glycogenolysis was reduced by 42% during the 15-min exercise challenge following training (198.8 +/- 36.9 vs. 115.4 +/- 25.1 mmol/kg dry muscle), and plasma epinephrine was blunted at 15 min of exercise. The Phos a mole fraction was unaffected by training. Muscle phosphocreatine utilization and free Pi and AMP accumulations were reduced with training at 7.5 and 15 min of exercise. It is concluded that posttransformational control of Phos, exerted by reductions in substrate (free Pi) and allosteric modulator (free AMP) contents, is responsible for a blunted muscle glycogenolysis after 6 days of endurance training. The increase in CS activity suggests that the reduction of muscle glycogenolysis was due in part to an enhanced mitochondrial potential.


2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 457-458
Author(s):  
Murillo C Pereira ◽  
Karen A Beauchemin ◽  
Tim A McAllister ◽  
Wenzhu Yang ◽  
Joyce Van Donkersgoed ◽  
...  

Abstract This study evaluated the effects of undigested neutral detergent fiber (uNDF) concentration and forage inclusion (FI) rate on dry matter (DM) intake, ruminal pH, reticular contractions, and gastrointestinal permeability for finishing beef cattle. Five ruminally cannulated Hereford′Simmental heifers (699±69.1 kg) were used in an incomplete 6×6 Latin square (26-d periods) with a 2×3 factorial treatment arrangement. Barley grain-based diets were formulated using barley silage or wheat straw to provide low or high uNDF (7.1 vs. 8.5% DM) with forage proportions of 5, 10, or 15% of dietary DM. Dry matter intake (P ≥ 0.10) and eating time (P ≥ 0.13) were not affected by uNDF, FI, or uNDF′FI. With low uNDF diets, increasing FI numerically (P = 0.02) increased rumination time (min/d); while, with high uNDF diets, rumination time increased with 5 to 10% FI, but not thereafter (P = 0.03). Mean ruminal pH was not affected by uNDF (6.17 vs. 6.19; P = 0.08), but increased with increasing FI (6.04b, 6.23a, and 6.28a; P = 0.02). Duration of ruminal pH < 5.5 was not affected by uNDF but tended (P = 0.07) to be reduced with increasing FI. High uNDF diet tended to increase the frequency of reticular contractions (1.43 vs. 1.51 contractions/min; P = 0.07) but decreased the contraction duration (13.2 vs. 14.1 sec; P = 0.04). Increasing FI increased contraction frequency (1.39b, 1.50a, and 1.53a contractions/min; P = 0.03) and tended to reduce contraction duration as forage increased from 5 to 10 and 15% (14.3, 13.1, and 13.6 sec; P = 0.07). Feeding high uNDF decreased (P = 0.05) permeability of the gastrointestinal tract based on the appearance of Cr-EDTA in urine following an intra-ruminal dose. Increasing FI tended to reduce gastrointestinal tract permeability (P = 0.06). Limited interactions indicate that uNDF and FI act independently suggesting that increasing dietary uNDF, without increasing FI rate, can stimulate frequency of reticulo-ruminal contractions and reduce gastrointestinal permeability for finishing cattle.


Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3126
Author(s):  
Tomasz Daszkiewicz ◽  
Andrzej Gugołek ◽  
Dorota Kubiak ◽  
Krzysztof Kerbaum ◽  
Ewa Burczyk

The aim of this study was to compare the fatty acid (FA) profile of meat from New Zealand White rabbits raised from 30 to 90 days of age under intensive (IPS) and extensive (EPS) production systems. In group IPS, the rabbits were housed in wire mesh cages with a slatted floor (16.7 animals/m2) and were fed a commercial pelleted diet. In group EPS, the rabbits were housed in free-standing cages on straw litter (2.5 animals/m2) and were fed a conventional farm-made diet (green fodder, barley grain, stale bread, hay). The FA profile of intramuscular fat (IMF) was analyzed in samples of Longissimus thoracis et lumborum (LTL) muscle. The analyzed production systems had no significant effect on the content of most FAs in IMF. However, the differences between group means contributed to more desirable values of the quality indicators of IMF (in particular in the LTL muscle) in group IPS. The study demonstrated that the claim that meat produced under less intensive farming systems is of superior quality could be an oversimplified generalization that should be validated in research.


1988 ◽  
Vol 64 (4) ◽  
pp. 1428-1432 ◽  
Author(s):  
E. J. Henriksen ◽  
M. E. Tischler

Contractile failure during various types of exercise has been attributed to intramuscular metabolic changes. We examined the temporal changes in force-generating capacity and metabolic state during intermittent isometric contractions in humans. One-legged quadriceps contractions at 30% maximum voluntary contraction (MVC) were executed for 6 s, with 4 s of rest between. The decrease in force-generating capacity was tested from brief MVC's and short bursts of 50-Hz stimulation applied at 5-min intervals. After 1 min of exercise, the MVC force declined linearly and in parallel to the 50-Hz stimulation force, indicating that the contractile failure was due to intramuscular processes. After 30 min of exercise the MVC force had declined by approximately 40% compared with the value obtained after 1 min. In separate experiments the same contraction protocol was followed, but two-legged contractions were used. Muscle biopsies taken after 5, 15, and 30 min of exercise showed only minor changes in the concentrations of glycogen, lactate, creatine phosphate (CrP), and ATP. However, at exhaustion, defined as loss of ability to sustain the target force, the concentrations of CrP and glycogen were reduced by 73 and 32%, and muscle lactate concentration had increased to 4.8 mmol/kg wet wt. Thus the gradual decline in force-generating capacity was not due to lactacidosis or lack of substrates for ATP resynthesis and must have resulted from excitation/contraction coupling failure, whereas exhaustion was closely related to phosphagen depletion, without significant lactacidosis.


2020 ◽  
Vol 98 (10) ◽  
Author(s):  
Karen M Koenig ◽  
Gwinyai E Chibisa ◽  
Gregory B Penner ◽  
Karen A Beauchemin

Abstract High grain diets are fed to finishing beef cattle to maximize animal performance in a cost-effective manner. However, a small amount of roughage is incorporated in finishing diets to help prevent ruminal acidosis, although few studies have examined optimum roughage inclusion level in barley-based diets. The objective of the study was to evaluate the effects of roughage proportion in barley-based finishing diets on growth performance, feeding behavior, and carcass traits of feedlot cattle. Crossbred beef steers (n = 160; mean body weight ± SD, 349.7 ± 21.4 kg) were allocated to 20 pens that were assigned randomly to four dietary treatments (five pens of eight steers per treatment). The treatment diets contained barley silage at 0%, 4%, 8%, and 12% of dietary dry matter (DM). The remainder of the diets (DM basis) consisted of 80%, 76%, 72%, and 68% barley grain, respectively, 15% corn dried distiller’s grains, 5% mineral and vitamin supplement, and 32 mg monensin/kg diet DM. The diets were fed as total mixed rations for ad libitum intake (minimum of 5% refusal) once per day. Cattle were weighed on 2 consecutive days at the start and end of the experiment and on 1 d every 3 wk throughout the experiment (124 d). Two pens for each treatment group were equipped with an electronic feeding system (GrowSafe Systems Ltd., Calgary, Alberta) to monitor feed intake and feeding behavior of individual cattle. The data for dry matter intake (DMI), average daily gain (ADG), gain:feed (G:F) ratio, and carcass traits were analyzed as a completely randomized design with fixed effect of barley silage proportion and pen replicate as experimental unit. Feeding behavior data were analyzed similarly, but with animal as experimental unit. Averaged over the study, DMI increased linearly (11.1, 11.3, 11.7, 11.8 kg/d; P = 0.001) as barley silage proportion increased from 0%, 4%, 8%, and 12% of DM, but ADG was not affected (carcass-adjusted,1.90, 1.85, 1.87, 1.89 kg/d; P ≥ 0.30). Consequently, G:F ratio decreased linearly (carcass-adjusted, 168.9, 163.8, 158.5, 160.6 g/kg DMI; P = 0.023). When averaged over the study, proportion of barley silage in the diet had no linear or quadratic effects (P > 0.10) on meal frequency, duration of meals, intermeal duration, or meal size, but eating rate decreased linearly with increasing silage proportion (P = 0.008). There was no diet effect on liver abscesses (P ≥ 0.92), and effects on carcass characteristics were minor or nonexistent. We conclude that increasing the proportion of barley silage in a feedlot finishing diet at the expense of barley grain to minimize the incidence of ruminal acidosis may decrease feed conversion efficiency.


1988 ◽  
Vol 68 (3) ◽  
pp. 811-820 ◽  
Author(s):  
J. J. KENNELLY ◽  
G. W. MATHISON ◽  
G. de BOER

Three factorial experiments were conducted to determine the relative feeding value of dry barley (DB) and high-moisture barley (HMB), and to evaluate the influence of method of ensiling (Pit vs. Harvestore® (HAV) silo), source of roughage (hay vs. silage), and level of concentrate (90 vs. 75%) on the performance and carcass characteristics of feedlot cattle. In exp. 1, 252 steers (initial wt 357 kg) were assigned on the basis of weight to six treatments (two pens × 21 animals per pen). A mixed diet consisting of 85.2% barley grain (dry matter (DM) basis) was offered free choice. The barley portion of the ration consisted of either 0, 25, 50, 75 or 100% DB with the balance being HMB from a pit silo. The sixth treatment consisted of feeding 100% HMB for the first 57 d and 100% DB for the remainder of the trial. Overall average daily gain (ADG) for steers fed 100% DB (1.70 kg d−1) was significantly higher than observed for animals fed 100, 75 or 50% HMB (1.46, 1.49 and 1.56 kg d−1, respectively). The kg of feed DM required per kg gain (FC) varied between 5.76 and 7.13 and was not (P > 0.05) influenced by treatment. No differences (P > 0.05) were observed in carcass characteristics. In exp. 2, 360 steers (initial wt 340 kg) were allotted on the basis of weight to six treatments designed to evaluate the effect of source (Pit vs. HAV) and level of HMB, in diets containing 10.2% silage, on animal performance. Overall ADG (1.11 – 1.17 kg d−1), FC (6.66 – 7.01) and carcass characteristics were similar (P > 0.05) for animals fed Pit HMB, HAV HMB and DB. In exp. 3, 264 weanling calves (initial wt 216 kg) were allotted on the basis of weight to six treatments which differed in type of barley (HMB vs. DB), source of roughage (hay vs. silage) and level of concentrate (75 vs. 90%; DM basis). The feeding period was 127 d. Daily gains varied between 0.78 and 0.91 kg d−1 and FC ranged from 6.40 to 7.10 and were not influenced (P > 0.05) by source of barley or source or level of roughage. While animals fed DB had significantly higher ADG than those fed HMB in exp. 1, the overall results from the three experiments indicate that on a DM basis HMB has similar feeding value to DB, and that there is no major difference between Pit and HAV-stored HMB for feedlot cattle. Key words: High moisture, barley, cattle, gain, feed conversion


1986 ◽  
Vol 26 (5) ◽  
pp. 527
Author(s):  
JC Spragg ◽  
RC Kellaway ◽  
TJ Kempton

Effects of cottonseed meal and cereal grain supplements on intake and utilisation of alkali-treated wheat straw were studied with 45 Friesian heifers (250 kg liveweight) in individual pens. Responses were measured in terms of feed intake and growth rate over 60 days. The basal diet fed ad libitum was coarsely milled wheat straw which was alkali-treated, sprayed with a solution containing urea, sulfur, copper and cobalt and sprinkled with dicalcium phosphate. Animals were also fed 800 g/day of 1 of 5 supplements: cottonseed meal (CSM), whole barley (WB), cracked barley (CB), ammonia-treated whole barley (NB) and extruded barley (EB). Intakes of the basal diet did not differ significantly between groups. Digestible organic matter in dry matter (%) was 53.1, 51.7, 47.2, 47.7, and 48.7 with supplements CSM, CB, WB, NB and EB, respectively; values for CSM and CB were significantly higher than for the other supplements (P< 0.05). Liveweight gains were 891,761,639, 657 and 784 g/day with the respective supplements, and did not differ significantly between CSM, CB and EB. We concluded that CSM did not stimulate intake of roughage more than supplements of barley grain, and that growth of the cattle was limited primarily by intake of energy.


1982 ◽  
Vol 22 (116) ◽  
pp. 155 ◽  
Author(s):  
SC Valentine ◽  
RB Wickes

Four groups of seven Friesian cows were offered 70% of their calculated metabolizable energy requirements as pasture hay and either 2.4, 4.8 or 7.2 kg/d of dry matter (DM) as wet brewers' grains or 3.9 kg DM/d as rolled barley. A further group of cows received no supplement. The quantities of brewers' grains offered were calculated from in vitro digestible DM content to provide lo%, 20% and 30%, respectively, of metabolizable energy requirements and the rolled barley 30% of metabolizable energy requirements. The cows consumed a mean of 2.2,4.3 and 6.1 kg DM/d, respectively, as brewers' grains and 3.9 kg DM/d as rolled barley. The daily yields of milk (litres), protein (kg) and solids not fat (kg), respectively, were greater (P < 0.05) for the cows offered brewers' grains at 4.8 kg DM/d (1 5.6,0.49, 1.36) and 7.2 kg DM/d (16.4, 0.54, 1.45) than for the cows offered rolled barley (13.3, 0.45, 1.21). Daily yields of milk fat from the cows offered either 4.8 or 7.2 kg DM/d of brewers' grains or rolled barley did not differ significantly. There were no significant differences between treatments in liveweight change. It was concluded that wet brewers' grains and rolled barley offered as supplements to dairy cows fed hay have similar nutritive values for milk production. It was calculated that for milk fat production the break even landed price ratio of brewers' grains to barley is 1:1.26.


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