High Plane Of Nutrition Research Articles

The Effect of Parental Age Gap on the Sex Ratio of Golden Lion Tamarins Born in Zoos

Manning et al. [1] investigated the effect of differences in age between human parents and the sex ratio of their offspring. They found that when men were older than their partners by 5 years or more, predominantly more male children were born. It has been suggested that older males and dominant males possess more re-sources and can pass these onto their sons and thereby enhance the transference of their genes into future generations [2]. Recently, Faust and Powell [3] demonstrated that, in primates, birth sex ratios in zoos are biased towards the dispersing sex (i.e., the sex with the greatest variation in reproductive success). Factors also known to have an effect on sex ratio in mam-mals are: (1) animals on a high plane of nutrition are predicted to produce more male than female offspring; (2) animals in good physical condition are predicted to pro-duce more male than female offspring; (3) animals of high social status are predicted to produce more male offspring; (4) higher population density results in more male offspring, and (5) a low level of stress results in more male offspring [4]. Manning et al.’s [1] study has been criticised by a number of authors [5–7] – principally concerning the small sample size and large number of uncontrolled vari-ables (e.g., social class and physical condition). Principally, we were interested in whether the parental age gap had an influence on birth sex ratio in a non-human primate species, the golden lion tamarin

Quality and Persistence of Forages in the Northern Great Plains

Integrating use of seedings of perennial cool-season grasses with native range is used to increase available forage and for maintaining a high plane of nutrition for grazing livestock. Our goal was to evaluate performance of yearling cattle and stand persistence of 3 released wheatgrass cultivars. Twice replicated 3-ha pastures were seeded to ‘Rosana’ western wheatgrass [Pascopyron smithii (Rydb.) A. Love], ‘Luna’ pubescent wheatgrass [Elytrigia intermedia (Host) Nevski], and ‘Hycrest’ crested wheatgrass {[Agropyron cristatum (L.) Gaertn.] ssp. desertorum (Fisch. ex Link) A. Love} in autumn 1994. Yearling steers (n = 8) grazed from 9 May to 12 June 1997 and 24 April to 15 June 1998. Yearling heifers grazed from 27 April to 18 June 1999. Hycrest produced the largest herbage standing crop in spring 1997 (912 kg ha -1 ) and 1998 (1,223 kg ha -1 ) (P < 0.05), but by spring 1999 standing crops averaged 656 kg ha -1 , and cultivars were not significantly different. Digestible organic matter standing crop did not differ among pastures of seeded species, but declined (P < 0.05) from May to June each year. Crude protein standing crop varied among cultivars (P < 0.05) in April and May 1998 and May 1999; however, no clear trends emerged. Crude protein standing crops consistently declined from April-May to June. Average daily gains were similar among cultivars in 1997, but greater (P < 0.05) on Hycrest (1.28 kg day -1 ) than Rosana (1.03 kg day -1 ) in 1998. Gains on Hycrest (0.74 kg day -1 ) and Rosana (0.78 kg day -1 ) were greater (P < 0.05) than on Luna (0.52 kg day -1 ) in 1999. These findings show in some years, Hycrest provided more forage in spring than Rosana, and will allow an increase in livestock numbers. Based on the encroachment of invading species, persistence of Luna is marginal of the 335-mm precipitation zone in the Northern Great Plains.

Effects of diet and body condition on fecal progestagen excretion in elk.

Recent research demonstrated the utility of fecal progestagens (P4) for detecting pregnancy in elk (Cervus elaphus) during mid- to late gestation. Several factors, however, may influence fecal P4 excretion and limit its use in free-ranging animals. We investigated the effects of nutrition and body condition (percent ingesta-free body fat) on fecal P4 concentrations and incidence of abortion. During mid-gestation (late December 1997 through early March 1998), 40 gravid cow elk varying in body condition were placed on three diets (high, medium, and low) in which the amount of food offered varied. Feces were collected periodically and analyzed for P4 via radioimmunoassay. We found no significant effect of dietary treatment on P4 concentrations, but as body condition declined, P4 concentrations declined significantly. This decline did not impede the ability to detect pregnancy based on previously reported criteria, even for elk in such poor condition that they aborted. However, fecal P4 concentrations in 10% (4/39) of samples collected from 13 non-pregnant animals maintained on a high plane of nutrition were false-positive for pregnancy. We suggest alternate criteria for determining pregnancy in elk using fecal P4 values: > 1.25 micrograms/g feces as pregnant, < 1.0 microgram/g feces as non-pregnant, and 1.0-1.25 micrograms/g feces as inconclusive. Finally, two cows that aborted did not abort until weeks after being classified as emaciated and near death, suggesting that nutrition-associated abortion in elk may not occur during mid-gestation except under extremely harsh conditions.

Quality and persistence of forages in the Northern Great Plains

Integrating use of seedings of perennial cool-season grasses with native range is used to increase available forage and for maintaining a high plane of nutrition for grazing livestock. Our goal was to evaluate performance of yearling cattle and stand persistence of 3 released wheatgrass cultivars. Twice replicated 3-ha pastures were seeded to 'Rosana' western wheatgrass [Pascopyron smithii (Rydb.) A. Love], 'Luna' pubescent wheat-grass [Elytrigia intermedia (Host) Nevski], and 'Hycrest' crested wheatgrass ([Agropyron cristatum (L.) Gaertn.] ssp. desertorum (Fisch. ex Link) A. Love) in autumn 1994. Yearling steers (n = 8) grazed from 9 May to 12 June 1997 and 24 April to 15 June 1998. Yearling heifers grazed from 27 April to 18 June 1999. Hycrest produced the largest herbage standing crop in spring 1997 (912 kg ha(-1)) and 1998 (1,223 kg ha(-1)) (P &lt; 0.05), but by spring 1999 standing crops averaged 656 kg ha(-1), and cultivars were not significantly different. Digestible organic matter standing crop did not differ among pastures of seeded species, but declined (P &lt; 0.05) from May to June each year. Crude protein standing crop varied among cultivars (P &lt; 0.05) in April and May 1998 and May 1999; however, no clear trends emerged. Crude protein standing crops consistently declined from April-May to June. Average daily gains were similar among cultivars in 1997, but greater (P &lt; 0.05) on Hycrest (1.28 kg day(-1)) than Rosana (1.03 kg day(-1)) in 1998. Gains on Hycrest (0.74 kg day(-1)) and Rosana (0.78 kg day(-1)) were greater (P &lt; 0.05) than on Luna (0.52 kg day(-1)) in 1999. These findings show in some years, Hycrest provided more forage in spring than Rosana, and will allow an increase in livestock numbers. Based on the encroachment of invading species, persistence of Luna is marginal of the 335-mm precipitation zone in the Northern Great Plains.

The effects of plane of nutrition and diet type on metabolic hormone concentrations, growth and milk production in high genetic merit dairy herd replacements

AbstractSeventy high genetic merit Holstein heifers were used in two experiments to investigate (1) the effects of plane of nutrition and diet type during the pre-pubertal period and (2) the effects of plane of nutrition during the post-pubertal period on metabolic hormone concentrations, growth and milk production. In experiment 1, treatment 1 and 2 heifers were given food to achieve a live-weight gain of 0·70 and 0·95 kg/day from 3 to 10 months of age on a grass silage based diet, while treatment 3 heifers were given food to achieve 0·95 kg/day on a barley straw/concentrate diet. During the pre-pubertal period, heifers reared on treatment 1 had significantly higher growth hormone(GH) concentrations (ng/ml per 1 h) than heifers reared on treatment 2 (P &lt; 0·01) and had significantly lower insulin concentrations than heifers reared on treatment 3 (P &lt; 0·01). Heifers reared on treatment 1 had significantly lower insulin-like growth factor 1 (IGF-1) concentrations than those reared on treatment 3 (P &lt; 0·01). At 10 months of age heifers reared on treatment 1 were of lower condition score (P &lt; 0·01) than those on treatment 2 and had a smaller heart girth diameter (P &lt; 0·01) than those on treatments 2 and 3. During the first lactation, milk yield and composition produced by the heifers was not significantly affected by treatment. In experiment 2, treatment A heifers were given, from 14 to 24 months of age, a low plane of nutrition to allow a live-weight gain of 0·65 kg/day on a grass silage and grass based diet during the winter and summer periods respectively. Treatment B heifers were kept on a high plane of nutrition to allow a live-weight gain of 0·90 kg/day on the same forage along with concentrate supplementation. During the rearing period, GH and IGF-1 concentrations were not significantly affected by treatment. Treatment A heifers weighed less before calving (P &lt; 0·05), had a lower condition score (P &lt; 0·01), and had a smaller heart girth diameter (P &lt; 0·01) than those on treatment B. During the first 10 weeks of lactation, heifers on treatment A had a higher silage dry matter intake and lost less weight (P &lt; 0·05) than those on treatment B, however, by 20 weeks of lactation these effects had disappeared. Milk yield and composition during the first lactation were not significantly affected by treatment. Overall, the findings of experiments 1 and 2 did not show any beneficial effects of higher weights at first calving in high genetic merit Holsteins and therefore indicate that accelerated growth in the pre- or post-pubertal period may not be required.

Effect of Superovulation Prior to Mating on Milk Production Performance During Lactation in Ewes

Thirty lactating ewes were used to evaluate the effect of superovulation on milk production. Twelve ewes had been injected, prior to mating, with 700 IU of pregnant mare serum gonadotropin; 18 ewes were injected with saline as a control. Thirteen ewes (nine control and four superovulated ewes) were fed at low plane of nutrition; the other ewes (nine control and eight superovulated ewes) were fed at high plane of nutrition. Superovulated ewes, fed at both low and high planes of nutrition, had dramatically higher milk yields (59%), and their milk composition was not changed. Plane of nutrition increased milk lactose and P contents without significant effect on milk production. The increased milk yields in the superovulated ewes were accompanied by increases in dry matter, gross energy intakes, and gross efficiency of milk synthesis. At the end of lactation, superovulated ewes had higher mammary dry fat-free tissue, total DNA, and total RNA. The results demonstrated that superovulation prior to mating dramatically increased milk production and efficiency regardless of plane of nutrition. Increased milk production and efficiency in the superovulated ewes were due to the increased mammary secretory cell numbers and their synthetic activities presumably through the increased endogenous hormonal stimulation of mammary growth and development during pregnancy.

Consequences of different patterns of feed intake during the estrous cycle in gilts on subsequent fertility.

The impact of different patterns of feed restriction between d 1 and 15 of the estrous cycle on subsequent reproductive performance of 23 trios of littermate gilts was tested. Some gilts were fed a high plane of nutrition (HH gilts) throughout the cycle, in contrast to HR gilts, which were restricted from d 8 to 15, and RH gilts, which were restricted from d 1 to 7. During feed restriction, weight gain in RH gilts (2.5 +/- .7 kg) was lower (P = .006) between d 1 and d 7 than in their HH and HR littermates (5.6 +/- .7 and 5.6 +/- .8 kg, respectively) and it was lower (P = .0001) in HR gilts (5.5 +/- .5 kg) between d 8 to d 15 than in their HH and RH counterparts (8.5 +/- .4 and 9.4 +/- .5 kg, respectively). There were no differences in backfat changes among groups. Embryonic survival in HR gilts at d 28 of gestation (68.3 +/- 4.8%) was lower (P < .05) than in HH and RH gilts (83.6 +/- 4.3 and 81.7 +/- 4.5%, respectively). Plasma progesterone concentrations in HR gilts were lower (P < .05) at 48 and 72 h after onset of standing estrus (.82 +/- .2 and 3.6 +/- .5 ng/mL, respectively) than in HH and RH gilts (1.44 +/- .2 and 1.24 +/- .2 ng/mL, 5.0 +/- .4 and 5.0 +/- .5 ng/mL, respectively at 48 and 72 h). No differences in ovulation rate were observed among treatments. Placental area was positively correlated to embryo size at d 28 (embryo size = .0003 x (area) + 18.35; r = .28, P = .03) but placental volume was negatively correlated to the number of embryos in utero (placental volume = -4.317 x (number) + 207.55, r = -.39, P = .002). These data demonstrate that the timing of feed restriction during follicular development has important consequences for subsequent embryo survival, possibly mediated by differences in progesterone concentrations in early pregnancy.

Intake and apparent digestibility of hay, haylage, big bale and clamp silage by ponies

Grass hay is the traditional conserved fodder fed to horses in the UK, yet good quality hay is often scarce and expensive. Working or breeding equines often require a higher plane of nutrition than that provided by hay, yet feeding high levels of concentrates can lead to a number of metabolic disorders such as colic and laminitis. Furthermore, the high dust content of hay can elicit the onset of the debilitating disorder, chronic obstructive pulmonary disease. Thus, there is increasing interest in feeding horses forage-based diets which are both low in dust and have enhanced nutritive values. The aim of this experiment was to determine the intakes and digestibility of four types of conserved forage by ponies.

Uterine luminal proteins and estrogens in gilts on a normal nutritional plane during the estrous cycle and on a normal or high nutritional plane during early pregnancy

In gilts, a high plane of nutrition during early pregnancy often results in increased embryo mortality, possibly related to changes in embryo-uterine asynchrony at a critical stage of pregnancy (around Day 11). Therefore, in the present study, uterine luminal proteins and estrogens were studied between Days 5 and 16 after the onset of estrus in gilts on either a normal (2.5 kg/d, cyclic and pregnant gilts) or a high (4.0 kg/d, pregnant gilts only) feeding level. Conceptus recovery rate between Days 5 and 12 was not affected by the feeding level during early pregnancy, neither were systemic progesterone levels. Between Days 9 and 11, dramatic changes took place in the protein composition of the uterine luminal 10kD+ proteins, shifting from most (90%) of the acidic proteins at Day 5 and 7 to approximately 50% at Day 11/12, especially due to an increase in basic proteins with an iso-electrical point of more than 8. This shift occurred most rapidly for the pregnant gilts at the high feeding level and least rapidly in the cyclic gilts, resulting in significant differences in the relative amount of acidic proteins at Day 10 and 11 after the onset of estrus (P < 0.05). Similarly, levels of estrogens in the uterine flushings at Days 10, 11 and 12 were always highest for the pregnant gilts on the high feeding level and were always lowest in the cyclic gilts (P < 0.05); pregnant gilts on the normal feeding level showed intermediate estrogen levels. The fact that gilts on a high feeding level during early pregnancy show more rapid changes in the uterine luminal protein composition and embryonic estrogen production seems to suggest that the rate of these changes may be related to embryo survival.

Dietary tea reduces the iron content of beef

We hypothesized that the lightness of Japanese beef was related to the concentration of heme iron. In Experiment 1, six Japanese Black heifers were allotted randomly to one of three treatment groups: a basal concentrate ration (40% flaked corn) or the same diet and either 2 kg/d wheat bran or 0.5 kg/d green tea. After feeding the diets for 174 d, the cattle were slaughtered and the M. longissimus thoracis, M. semimembranosus, and M. gluteus medius were sampled for meat color, iron, and lipid content. The iron content of the M. semimembranosus from the tea-fed cattle was lower than in M. semimembranosus from the control cattle, and a∗ (redness) and √(a ∗2+b ∗2) (saturation) values were lower in M. semimembranosus from bran- and tea-fed cattle than in control cattle. Treatment main effects (across muscles) indicated that inclusion of tea in the diet increased intramuscular lipid and reduced the muscle iron content. There was a significant negative correlation ( r 2=0.79) between muscle iron content and L ∗ value (lightness). For Experiment 2, the effect of beef breed type on meat color and iron content of M. longissimus thoracis was investigated using stored meat samples from six breeds from a previous fattening experiment done under a high nutritional plane. Muscle iron content was significantly lower in Japanese Black cattle than in Japanese Black × Holstein or Japanese Black × Japanese Black/Holstein. There was no relationship between muscle iron content and intramuscular lipid content ( r 2=0.001). In Experiment 3, samples of M. longissimus dorsi were obtained from 17 Wagyu crossbred and 3 Angus crossbred cattle fed a corn concentrate diet in the USA for 148 d. Iron content of the M. longissimus thoracis from Japanese Black and Japanese Brown × Holstein cattle fattened in Japan was significantly less than the iron content of M. longissimus dorsi from cattle raised in the USA. Overall, the data indicate that it is possible to lower muscle iron, and lighten muscle color, by feeding green tea to Japanese cattle; also, there may be a genetic basis for the lower iron, and lighter color, of beef produced in Japan.

Switching maternal dietary intake at the end of the first trimester has profound effects on placental development and fetal growth in adolescent ewes carrying singleton fetuses.

The aim was to investigate whether placental growth and hence pregnancy outcome could be altered by switching adolescent dams from a high to a moderate nutrient intake, and vice-versa, at the end of the first trimester. Embryos recovered from adult ewes inseminated by a single sire were transferred in singleton to peripubertal adolescents. After transfer, adolescent ewes were offered a high (H, n = 33) or moderate (M, n = 32) level of a diet calculated to promote rapid or moderate maternal growth rates, respectively. At Day 50 of gestation, half the ewes had their dietary intakes switched, yielding 4 treatment groups: HH, MM, HM, and MH. A subset of ewes were killed at Day 104 of gestation to determine maternal body composition in relation to growth of the products of conception. Maternal body composition measurements revealed that the higher live weight in the high-intake dams was predominantly due to an increase in body fat deposition, with a less pronounced increase in body protein. At Day 104, HH and MH groups (high intake during second trimester) compared with MM and HM groups (moderate intake during second trimester) had a lower (p < 0.002) total fetal cotyledon weight; but fetal weight, conformation, and individual organ weights were not significantly influenced by maternal dietary intake. In ewes delivering live young at term, a high plane of nutrition from the end of the first trimester (HH and MH groups) compared with moderate levels (MM and HM groups) was associated with a reduction in gestation length (p < 0.009), total placental weight (p < 0.002), total fetal cotyledon weight (p < 0.001), and mean fetal cotyledon weight per placenta (p < 0.001). Fetal cotyledon number was dependent on maternal dietary intake during the first trimester only and was lower (p < 0.007) in HH and HM ewes compared to MM and MH ewes. The inhibition of fetal cotyledon growth in HH and MH groups was associated with a major decrease (p < 0.001) in lamb birth weight at term relative to the MM and HM groups. Thus, reducing maternal dietary intake from a high to a moderate level at the end of the first trimester stimulates placental growth and enhances pregnancy outcome, and increasing maternal dietary intake at this time point has a deleterious effect on placental development and fetal growth.

Moderate Doses of Porcine Somatotropin do not Increase Plasma Insulin-Like Growth factor-I (IGF-I) or IGF Binding Protein-3

The growth rate of the young pig is generally much less than its potential and may be constrained by endocrine status as well as by nutrient intake. The aim of this study was to determine whether porcine somatotropin (pST) could increase growth in the nursing pig. Fourteen sows nursing litters of 6 ( n = 7) or 12 ( n = 7) piglets were utilized to establish a high and low plane of nutrition for sucking pigs. On Day 4 of lactation, the median two male pigs from each litter were randomly allocated to one of two doses of pST (0 or 60 μg/kg/d) until weaning on Day 31. Pigs were bled on Days 4, 13, 22, and 31 of lactation and the plasma was analyzed for insulin-like growth factor (IGF)-I, IGF-II, and IGF binding protein-3 (IGFBP-3). Pigs were weaned into conventional accommodation and further weighed on Days 63, 91, and 119. Pigs from litters of 6 grew more quickly and weighed 2.2 kg (P = 0.01) and 3.5 kg (P = 0.04) more than pigs from litters of 12 at 31 and 63 d of age, respectively. There was no effect of pST on preweaning growth of sucking pigs (261 vs. 258 g/d, P = 0.68), although growth rate increased in the final 3 d before weaning at 31 d (241 vs. 294 g/d, P = 0.01). IGFBP-3 was greater (1.09 vs. 0.78 μg/ml, P < 0.001), whereas IGF-I tended to be greater (206 vs. 176 ng/ml, P = 0.14), in pigs from the small litters. There was no effect of pST on plasma IGF-I (182 vs. 195 ng/ml, P = 0.454) or IGFBP-3 (0.93 vs. 0.94 μg/ml, P = 0.85) concentrations. Plasma IGF-I and IGFBP-3 were highly correlated with the growth rate of nursing pigs (R = 0.638 and 0.756, respectively). There were no effects of pST (340 vs. 328 ng/ml, P = 0.48) or litter size (336 vs. 333 ng/ml, P = 0.88) on IGF-II. In conclusion, pST had no little or no effect on growth performance or plasma IGF-I, IGF-II, or IGFBP-3 in sucking pigs on either a high or low plane of nutrition.

Effects of body condition at calving, post-partum nutrition and calf access on the interval from calving to first ovulation in beef cows: Cow performance and metabolism

The prolonged interval from calving to first ovulation in beef cows is primarily due to the suckling-mediated inhibition of pulsatile LH release. Undernutrition both before and after calving also suppresses LH release, reduces ovarian follicular growth and delays ovulation. The interactive effects of these factors on the interval from calving to first ovulation in beef cows were quantified by studying the incidence of ovulation, following acute calf isolation and once-a-day suckling (restricted access), after emergence of the fourth follicular wave post partum in cows in differing body condition at calving and offered low or high planes of nutrition after calving.The experiment was a 2 x 2 x 2 factorial design, in which the factors were body condition score at calving (Low v. Moderate), feeding level after calving (0.6 v. 1.0 MJ ME/d/kg M0.75), and restricted (once-a-day) v. ad libitum access and suckling. The experiment, duplicated at each of the four participating sites, involved 16 Simmental, 16 Sarda, 16 Brown Swiss and 16 Hereford x Friesian multi-parous cows. Follicle growth was monitored daily from day 21 post partum until the earlier of second ovulation or Day 90 post partum using transrectal ovarian ultrasonography.

Influence of prepartum body condition score change on reproduction in multiparous beef cows calving in moderate body condition.

Multiparous, spring-calving beef cows (n = 250) were used to determine whether large changes in body energy reserves during mid- to late gestation influenced subsequent reproductive performance of cows calving in moderate body condition. In three states, cows were blocked by BW and body condition score (BCS; 1 = emaciated to 9 = obese) then allotted to receive either a high or low plane of nutrition from late summer to early winter over a 3-yr period. This generated an array of BCS by the beginning of the last trimester of pregnancy when cows were grouped by BCS as follows: Group 1, BCS < or = 4; Group 2, BCS of 5 or 6; and Group 3, BCS > or = 7. Each group was managed so that individual cows would calve with a BCS of 5 to 6. At the time of group assignment, mean BW and BCS differed (P < .01) among groups and were 480 kg and 3.6, 541 kg and 5.5, and 594 kg and 7.1 for Groups 1 to 3, respectively. Within 28 d before calving, BW and BCS were similar (P > .20) among groups averaging 555 kg and 5.1. Prepartum BCS changes averaged 1.4, -.4, and -2.0 units for Groups 1 to 3, respectively (P < .01). Cows were managed as a single group after calving in each state. Location effect was significant for the prepartum and postpartum BW and BCS changes but not for postpartum reproductive performance. Significant location x BCS group interactions were found for the 90-d prepartum BW, BCS at calving, and prepartum changes in BW, but were caused by differences in magnitude among locations. The percentage of cows with luteal activity at the start of a subsequent breeding season was not affected (P > .20) by either location or BCS group, and averaged 66%. Mean pregnancy rates at 20, 40, and 60 d of a subsequent breeding season were 55, 76, and 89% for Group 1; 51, 67, and 82% for Group 2; and 64, 79, and 89% for Group 3 (P > .30). Mean days to conception were 89, 87, and 85 for Groups 1 to 3, respectively (P = .70). Neither calf birth weight (x = 38.6 kg) nor adjusted 205-d weight (x = 223.6 kg) were affected by prepartum BW and BCS changes. We conclude that reproductive performance of cows calving in moderate body condition is not influenced by large changes in body energy reserves during the last trimester of pregnancy.

Effect of different planes of nutrition on urea molasses mineral block intake, nutrient utilization, rumen fermentation pattern and blood profile in Murrah buffaloes ( Bubalus bubalis)

In order to investigate the effect of plane of nutrition on intake and nutrient utilization from urea molasses mineral block (UMMB), rumen fermentation pattern and blood biochemical constituents, 20 intact and 12 rumen fistulated male Murrah buffaloes aged about 3 years and weighing 320.3±13.11 kg were randomly distributed into four groups of eight animals in each, thus each group having five intact and three rumen fistulated buffaloes. All the animals were fed individually for 40 days. Animals in group I (control) were fed ad libitum wheat straw alone along with mineral mixture and common salt, group II, III and IV were given ad libitum wheat straw alongwith increasing levels of energy from UMMB alone (group II), UMMB+700 g concentrate mixture (group III) and UMMB+1400 g concentrate mixture (group IV). Crushed barley fortified with mineral mixture and common salt was the concentrate mixture used. At the end of feeding trial, a metabolism trial of 7 days duration was conducted on intact animals to determine the digestibility of nutrients. Rumen fermentation study was carried out on 12 rumen fistulated animals following the metabolism trial, blood was collected from intact animals to estimate the nitrogenous constituents in blood serum of animals fed on different planes of nutrition. The intake of total dry matter (DM) and total digestible nutrients (TDN) was non-significantly and intake of digestible crude protein (DCP) was significantly ( p<0.01) higher in treatment groups over control group. Apparent digestibility of DM, organic matter (OM), and crude protein (CP) increased significantly ( p<0.01) in group II to IV over group I, whereas, the digestibility of neutral detergent fibre (NDF), acid detergent fibre (ADF), cellulose and hemicellulose tended to be higher in UMMB fed groups. Nitrogen intake and its balance increased significantly ( p<0.01) with the increase in plane of nutrition. Significantly ( p<0.01) higher concentration of total volatile fatty acids (TVFA), total nitrogen (TN) and its fractions were observed due to increased plane of nutrition. The rumen pH reduced significantly ( p<0.01) due to concentrate feeding in group III and IV, but rumen fluid volume and digesta flow rate were unaffected. The concentration of blood serum urea increased significantly ( p<0.01) in experimental groups as compared to control but ammonia–N and total protein concentrations were unaffected due to feeding of animals on different plane of nutrition. Results indicated that additional energy supplied through concentrate in group III and IV, respectively, resulted in higher intake of protein and energy than the maintenance requirement (Kearl, L.C., 1982. Nutrient Requirements of Ruminants in Developing Countries. International Feed Stuffs Institute, Utah State University, Logan, UT, 82 pp), whereas wheat straw supplemented with UMMB was sufficient to meet the maintenance requirements of adult buffaloes. Higher plane of nutrition did not have any positive effect on intake of wheat straw and UMMB.

Effects of restriction of growth and development of Brecon Cheviot ewe lambs on subsequent lifetime reproductive performance

The effects on the lifetime reproductive performance of female sheep of two levels of nutrition before they were weaned or during their adult life were investigated using 499 Brecon Cheviot sheep, a breed which exhibits only small reproductive responses to contemporary nutritional manipulations. Female sheep subjected to a restricted level of nutrition prior to weaning had a significantly lower lifetime incidence of multiple births than those on a high plane of nutrition ( P<0.05) but not when restriction took place in adult life. Nutritional restriction did not significantly affect the proportions of barren ewes, irrespective of the time at which it was applied. There were positive relationships between the nutritional treatment in both, early ( P<0.05) and adult life ( P<0.01) and the birth weight of lambs born to these ewes. It is concluded that undernutrition of female lambs of this breed during the first months of life results in a reduction in lifetime reproductive performance, irrespective of nutrition during adult life, and that food resources should be diverted, where possible, to this phase of the production cycle to ensure that subsequent reproductive performance is not compromised.

Growth and metabolism of fetal and maternal muscles of adolescent sheep on adequate or high feed intake: possible role of protein kinase C-alpha in fetal muscle growth.

From days 4-104 of pregnancy, adolescent sheep, weighing 43.7 (SE 0.87) kg were offered a complete diet at two different intakes (approximately 5 or 15 kg/week) designed to meet slightly, or well above, maternal maintenance requirements. The fetal and maternal muscles were taken on day 104 of pregnancy and analysed for total DNA, RNA and protein. Ewes offered a high intake to promote rapid maternal weight gain, weighed more (76.5 (SE 4.5) v 50.0 (SE 1.7) kg) and had muscles with a greater fresh weight, whilst their fetuses had smaller muscles, than those fed at a lower intake. Plantaris muscle of the ewes fed at the high intake contained more RNA and protein; again the opposite situation was found in the fetal muscle. On the higher maternal intakes, the DNA, RNA and protein contents of the fetal plantaris muscle were less than in fetuses of ewes fed at the lower intake. To investigate the possible mechanisms involved in this decrease in fetal muscle mass, cytosolic and membrane-associated muscle proteins were subjected to Western immunoblotting with antibodies to nine isoforms of protein kinase C (PKC), a family of enzymes known to play an important role in cell growth. Five PKC isoforms (alpha, epsilon, theta, mu, zeta) were identified in fetal muscle. One of these, PKC-alpha was located predominantly in the cytosolic compartment in the smaller fetuses of the ewes fed at a high plane of nutrition, but was present to a greater extent in the membranes of the more rapidly growing fetuses of the ewes fed at the lower intake. This was the only isoform to demonstrate nutritionally related changes in it subcellular compartmentation suggesting that it may mediate some aspects of the change in fetal growth rate.

Population structure and dynamics in captive muskoxen at the Large Animal Research Station, 1988-1994

The muskox colony at the Large Animal Research Station, started in 1979, totaled 22 individuals before calving in 1988. Between 1988 -1994 cows of breeding age have been maintained on either a high plane (HP) or low plane (LP) of nutrition, and as far as possible, female offspring are kept with their mother's group. During this time the population has increased from 22 to 43 animals (25 females and 18 males). Fifty-four calves were born with an overall sex ratio of 52:48 (male:female). When partitioned between the 2 nutritional planes the sex ratio was HP 45:55 and LP 62:38. The calf/cow ratio was 0.83 in 1988 and 0.86 in 1994. The LP group accounted for most of the variability in pregnancy rate, primarily through delayed puberty and breeding pauses. Calf mortality was due mainly to abortions, stillbirths and neonatal death (n=12), 7 deaths occurred between 2 weeks and 1 year of age. All stillbirths and abortions (n=4) and 6 of 8 neonatal deaths affected calves of HP cows. Thirteen adults died, 4 males were loaned to other facilities and 2 new calves were added.

Fattening heifers to heavy weights to enhance marbling: Efficiency of gain

Feedlot performance and carcass composition were measured in two studies to evaluate the use of common Canadian breeds and nutrition programs for production of highly marbled beef for the Japanese market. Weaned heifer calves (n = 221, initial weight 265 kg) of Angus, Hereford, and Hereford × Angus (HA) breeding were slaughtered at 500, 590, and 680 kg in exp. 1. In exp. 2, yearling heifers (n = 216, initial weight 395 kg, same breeds as exp. 1 but including Holstein) were slaughtered at 590 and 680 kg. Cattle were randomly assigned to either a high plane of nutrition (HP) until slaughter or a moderate plane of nutrition to 500 kg (exp. 1) or 550 kg (exp. 2), followed by a high plane to slaughter (MHP). Mean days on feed, percent carcass fat, and percent intramuscular fat in longissimus muscle were 347 d, 38.6%, and 8.50% in exp. 1, and 281 d, 37.5%, and 7.87%, respectively, in exp. 2. In exp. 1, Herefords produced the most economical gains but the fattest carcasses (P &lt; 0.05). In exp. 2, Holsteins had the most economical liveweight and lean carcass weight gains (P &lt; 0.05). The cost of a percentage increase in intramuscular fat was lowest for Angus in exp. 1 (P = 0.05), similar for the breeds in exp. 2 (P = 0.29), and not affected by slaughter weight group. HP cattle gained liveweight, carcass, lean carcass, and intramuscular fat more economically than did MHP cattle (P ≤ 0.0002). The rate of deposition of intramuscular fat did not appear to increase with maturity. Feeding cattle to extreme slaughter weights using conventional feedlot diets produced extremely fat carcasses but did not produce highly marbled beef. Key words: Beef cattle, carcass, growth, intramuscular fat, marbling

Meat quality of heifers fattened to heavy weights to enhance marbling

Marbling is the primary factor affecting quality grades of youthful grain-fed cattle in the Canadian, American and Japanese grading systems. Cattle were fed for an extended period of time and to extreme slaughter weights to enhance marbling. The effects of slaughter weight, breed, nutrition, and grading site (12/13th rib-Canadian or 6/7th rib-Japanese) on meat quality were evaluated using 221 weaned heifer calves (exp. 1) and 216 yearling heifers (exp. 2) raised on high (HP) or moderate-high (MHP) planes of nutrition. Mean intramuscular fat concentration in longissimus muscle was 6.93, 8.94, and 9.86% at mean slaughter weights of 500, 590, and 680 kg, respectively (exp 1) and 6.84% and 9.02% at 590 and 680 kg (exp. 2). HP carcasses had more intramuscular fat and lower shear values and drip losses than MHP carcasses (P ≤ 0.05). Angus carcasses had more intramuscular fat and lower shear values than the other breeds studied. Holsteins on the HP diet produced tender meat with a high amount of intramuscular fat whereas Holsteins on the MHP diet produced tougher meat with less intramuscular fat (P &lt; 0.05). The 6/7th rib site had lower marbling scores, lighter meat, higher drip losses and lower shear values (P ≤ 0.001) than the 12/13th rib site. Intramuscular fat accounted for only 3 to 7% of the variation in shear force. Breed, nutrition, and slaughter weight had little effect on most measurements of meat quality except intramuscular fat and shear force. Key words: Beef cattle, meat quality, intramuscular fat, tenderness