High Plane Of Nutrition Research Articles

84 DEVELOPMENTAL EFFECTS OF CHOLESTEROL-ENRICHED HYPERLIPIDIC DIETS IN RABBITS

The long-term effects of low birth weight on the onset of adult metabolic diseases have been described in several species. Low birth weight is usually due to maternal food restriction or placental insufficiency during pregnancy. In contrast, the effects of maternal high planes of nutrition or dietary unbalance have been less studied. In previous work, we have shown that the administration of a hypercholesterolemic (0.2%) hyperlipidic (8%) diet to rabbit does throughout puberty and subsequent pregnancy significantly affected fetal and postnatal development of their offspring. The aim of this study was to determine the relative role of cholesterol and of the n3/n6 fatty acid ratio on fetal development using the same model. Twenty-five does were fed from 10 weeks of age with 1 of 5 diets: S or SC (soy oil, 9% lipids, n3/n6 = 0.15 without or with 0.1% cholesterol), R or RC (rapeseed, 8% lipids, n3/n6 = 0.38 without or with 0.1% cholesterol), or Co (2% lipids, no cholesterol). Does were bred at 18 weeks of age. The growth of 4 fetuses per dam was monitored by weekly ultrasound scanning (Chavatte-Palmer P et al. 2008 Theriogenology). All pups were weighed at birth. Additionally, fetuses and placentas from a further 2 to 4 does per treatment group were collected at 15 days of pregnancy. Data were analyzed by ANOVA using group, number of fetuses, and dam as variables. Because different measurements were taken at different stages, the analysis of repeated measures could not be performed. Although maternal lipid intake was significantly increased in all treated groups, does adjusted their intake so that caloric intake and doe body weight were not statistically different between groups. Mean litter size was not different between groups. Group and, to a lesser extent, dam, but not litter size, significantly affected fetal development. Conceptus length was reduced on Day 9 of pregnancy in SC (–14%) and RC (–5%) compared with Co (P < 0.05). Fetal length was reduced on Day 15 in groups RC and S (both –9%, P < 0.05) but not in SC. Fetal abdominal perimeter measurements were smaller in SC, RC, and R at Day 22 and in SC at Day 28 (P < 0.05). Birth weight was decreased in all groups (–10, –18, –21, and –7% in SC, S, RC, and R, respectively compared with Co). Postmortem analyses did not show significant differences in fetal weight at Day 15, but placentas were significantly heavier in S compared with all other groups (P < 0.05). In conclusion, long-term cholesterol- and lipid-enriched diets induced intrauterine growth retardation in does with variable effects according to the n3/n6 fatty acid ratio and cholesterol dietary content, with more significant effects observed in the cholesterol-enriched diets. These effects are observed very shortly after implantation, indicating that oocyte and/or embryonic development may be affected. Further work is in progress to evaluate these early effects, using micro-array analysis of gene expression in the embryos.

The effects of maternal health and body condition on the endocrine responses of neonatal foals

Chronic and acute alterations in maternal nutrient intake during pregnancy alter pancreatic and hypothalamo-pituitary-adrenal (HPA) axis function in the offspring, before and after birth. Little is known about these effects. To determine whether maternal nutrient restriction caused by natural infection with Streptococcus equi altered endocrine function in neonatal foals born from mares fed a maintenance or high plane of nutrition throughout pregnancy. Ten primiparous mares received either a diet to maintain moderate body condition score (Moderate, n = 5) or a near ad libitum feeding regime to maintain a high body condition score (High, n = 5) throughout pregnancy. All mares inadvertently became infected with Streptococcus equi in mid gestation and lost approximately 10% body mass. Maternal insulin and glucose concentrations decreased (P < 0.05) during, and one month following, the weight loss period. High mares weighed more (P < 0.05) at parturition than Moderate mares; all foals were healthy. Gestational age, foal bodyweights, placental and clinical parameters after birth were no different between the 2 groups. Foal plasma cortisol and glucose responses to exogenous adrenocorticotrophic hormone and insulin, respectively, were similar for both groups. Insulin concentrations during glucose tolerance test were significantly higher (P < 0.05) in foals from Moderate than High mares and compared with foals studied previously from healthy, well-fed mares, suggesting that the beta cell sensitivity to glucose was enhanced in Moderate. Acute nutrient restriction in mid gestation caused by maternal illness and inappetence, superimposed on a maintenance feed intake throughout pregnancy, enhanced insulin secretion to glucose in foals. Nutritional programming of pancreatic beta cells, but not the HPA axis, appeared to depend on the level of nutrition before and after the weight loss period. Disturbances in neonatal pancreatic beta cell function programmed during pregnancy may predispose foals to metabolic problems in later life.

Creatinine and pseudouridine in plasma and urine from Brahman-cross steers fed a low, medium or high plane of nutrition

Metabolic state as influenced by growth rate may influence meat toughness and can be estimated from metabolites excreted in urine. Urine collection over 24 h requires animals to be constrained in metabolism crates for many days. Single blood sampling to estimate metabolites in plasma would be less stressful on animals than collecting 24 h urine excretion. This study investigated the hypothesis that the plasma concentrations of pseudouridine and creatinine were representative of those found in 24 h urine excretions in steers fed different quality diets. Eleven Brahman-cross steers were fed a high ( n = 3), medium ( n = 4) or low ( n = 4) quality hay diet for three weeks. Steers were catheterized and housed in metabolism crates for 6 days. Urine was collected every 24 h and total volume sub-sampled for analyses of creatinine and pseudouridine. Jugular blood was collected from each steer every 3 h from 07:30 to 16:30 h. Plasma was separated from red blood cells by centrifugation and frozen for creatinine and pseudouridine analyses. No time of day effect was apparent for pseudouridine or creatinine so daily means were used to test for effect of diet and to relate to urinary concentrations. Nutritional restriction halted live weight gain but had no effect on urinary or plasma pseudouridine, suggesting that diet did not affect tRNA turnover. Increased plasma creatinine concentrations and reduced urinary creatinine concentration in steers experiencing nutritional restriction indicated that their renal clearance rate decreased. As a result, the ratio of plasma pseudouridine to creatinine concentration was not directly proportional to that of 24 h urinary excretion.

Regulation of mammary parenchymal growth by the fat pad in prepubertal dairy heifers: role of inflammation-related proteins

In prepubertal heifers, the mammary parenchyma consists of epithelial and myoepithelial cells growing within a mammary fat pad (MFP). The MFP produces IGF-I that stimulates epithelial cell proliferation. In other species, adipose tissue expansion induces inflammation-related proteins (IRP), such as tumor necrosis factor alpha (TNFalpha), interleukin (IL)-6, IL-1beta transforming growth factor beta, monocyte chemoattractant protein 1 (MCP-1), and plasminogen activator inhibitor-1 (PAI-1). The MFP production of IRP may influence mammary development because they impair not only insulin but also IGF-I actions. Moreover, the MFP expansion seen with development and increased nutrition coincides with reduced parenchymal growth. Our first objective was to identify IRP capable of altering proliferation of bovine mammary epithelial cells. TNFalpha, but neither IL-6, IL-1beta MCP-1 nor PAI-1, inhibited basal and IGF-I-stimulated proliferation in MAC-T cells and primary cells isolated from heifers. Our second objective was to determine whether MFP expression of IRP changed in a manner consistent with inhibition of parenchymal growth. MFP expression was measured from 100 to 350 kg body weight (experiment 1) or at 240 kg body weight (experiment 2) in dairy heifers offered restricted or high planes of nutrition. In experiment 1, neither nutrition nor development altered MFP expression of TNFalpha. Nutrition increased MCP-1 and PAI-1 but only before MFP expansion and after cessation of allometric parenchymal growth. In experiment 2, nutrition increased TNFalpha and PAI-1, but not MCP-1. Thus, MFP expansion increases IRP production in cattle, but this is unlikely to contribute to reduced parenchymal growth observed with development or increased nutrition.

Histochemical properties and collagen architecture of M. iliotibialis lateralis and M. puboischiofemoralis in male broilers with different growth rates induced by feeding at different planes of nutrition

1. The histochemical properties and the collagen content and architecture of the iliotibialis lateralis (ITL) and puboischiofemoralis (PIF) muscles were assessed in Red Cornish × New Hampshire cockerels reared on a high nutrient plane for 80 d (H80d), or a low nutrient plane for 80 d (L80d) or 95 d (L95d). 2. Final live weights were 3410 g in H80d, 2810 g in L80d and 3467 g in L95d. Both ITL and PIF muscle weights were lowest in L80d and did not differ between H80d and L95d. 3. ITL muscle was composed of fast-twitch myofibres such as IIA (high reduced nicotinamide adenine dinucleotide dehydrogenase, NADH-DH activity), IIB (low NADH-DH activity) and IIC (intermediate NADH-DH activity). The high percentage of type IIB myofibres in H80d (76·6%) and L95d (76·2%) birds were reflected in low percentages of type IIC myofibres (12·2%) in H80d birds and type IIA myofibres (8·2%) in L95d birds. Percentages of IIA, IIB and IIC myofibres in L80d cockerels were 12·4, 69·8 and 17·6%, respectively. 4. The myofibres in PIF muscle were divided into two basic types, I and IIA, and a transitional form (I-tr) from IIA to I. In the caudal region, all myofibres in H80d and L95d cockerels were type I but in L80d cockerels 15% of myofibres were categorised as type I-tr. In the cranial region, the great majority (52 to 63%) of myofibres were type IIA. Type I myofibres occurred at a higher percentage in H80d (30·5%) than L95d (21·8%) and type I-tr in L95d (15·7%) than H80d (7·3%) and L80d (11·5%). 5. The total amount of collagen was higher in ITL than PIF muscle in every bird group. In both muscles the highest collagen content was in L95d cockerels but the content did not differ between H80d and L80d birds. The thickness of thick and thin perimysia increased with muscle size. The circular collagen fibre in the thick perimysium was larger in ITL (6·1 to 7·0 µm) than PIF (3·7 to 3·8 µm) muscle but did not differ among the bird groups. 6. From these results, it was concluded that feeding on a high nutritional plane promotes growth of the thigh muscles, with accompanying enlargement of the perimysial thickness, no increase in collagen content and various changes of histochemical properties.

Carcass traits of Kheri lambs maintained on different system of feeding management

The study was conducted on 6-month-old finisher lambs of the Kheri breed raised under extensive range management (G1), grazing with ad libitum concentrate supplementation (G2) or intensive feeding (G3) to assess dressing yield, cutability of standard cuts, composition of the carcass and the efficiency of mutton production from the three defined systems. The weaning weight of the lambs in the three groups was similar while the finishing weight, total body weight gain in the experiment, average daily gain and the percent feed conversion efficiency were higher ( P < 0.01) in G2 and G3 than G1. The pre slaughter weight (PSW), empty live weight (ELW), hot carcass weight and hot carcass weight with edible offal was higher ( P < 0.01) in G2 and G3 fed on a high plane of nutrition than G1 raised under extensive range management. The dressing percent in terms of live weight (LW) and empty live weight (ELW) was also higher in G2 and G3 than G1. The loin eye area as an index of muscle growth was also higher in G2 and G3 than G1. Although the weights of standard cuts were generally higher in G2 and G3 due to higher PSW, as proportions of half carcass they were similar in the three groups, except the rack cut, which was higher in G2 and G3. The cut proportions pooled for the three groups averaged 33.2%, 12.3%, 13.3%, 24.9% and 16.3% of half carcass for leg, loin, rack, neck and shoulder and breast and fore shank, respectively. The depot fat (Caul and kidney fat) accretion was higher in G2 and G3 than G1. The composition of the half carcass indicated that lean percent was higher ( P < 0.01) in G1 and G2 than G3 while sub cutaneous and intra muscular fat content were generally higher ( P < 0.01) in G2 and G3 and KOH bone percent was higher ( P < 0.05) in G1 and G2 than G3. The results indicated that the growth performance was better, feed conversion efficiency, carcass yield and dressing percentage higher in lambs maintained under grazing with supplementation and intensive feeding than extensive range management. The carcass separable fat content was 8% under extensive range management while it was 12% and 16% in semi intensive and intensive system of feeding management indicating that the carcass was of acceptable quality. The loin eye area reflected the trends of pre slaughter weight and was higher in intensive and semi intensive than extensive range management.

Feeding Broiler Breeder Males. 2. Effect of Cumulative Rearing Nutrition on Body Weight, Shank Length, Comb Height, and Fertility

Two experiments were conducted to evaluate the effects of 2 planes (low and high) of cumulative nutrient intake during the rearing period on performance of broiler breeder males. The low cumulative nutrition program supplied 29,580 kcal of ME and 1,470 g of CP, whereas the high cumulative nutrition program supplied 33,500 kcal of ME and 1,730 g of CP to photostimulation at 21 wk of age. Two diets (LoDiet and HiDiet) were used with a single feeding program in experiment 1. In experiment 2, a single diet with 2 feeding programs (LoFeed and HiFeed) was used. In experiment 1, the 2 diets were blended from 21 to 24 wk to provide a gradual transition to a single common laying breeder diet that was fed during the production period. At 21 wk of age in experiment 2, males were divided into light or heavy BW groups to complete a 2 x 2 factorial design during the production period. The high plane of nutrition increased BW, shank length, and comb height during the rearing period, but the differences disappeared after 28 wk of age. Retrospective analysis showed that the heavy males at 21 wk of age in experiment 2 were also the heaviest males at 8 wk of age. Both low plane groups (LoDiet in experiment 1 and LoFeed in experiment 2) exhibited better fertility during late production. A cumulative nutrient intake during the rearing period of 29,580 kcal of ME and 1,470 g of CP was minimally sufficient for subsequent male reproductive performance.

Serum from heifer calves treated with bovine growth hormone affects the rate of proliferation of C2C12 myogenic cells dependent on the plane of nutrition: the role of insulin‐like growth factor‐I and IGF‐binding proteins‐2 and ‐3

The present in vitro experiments were carried out in order to study whether variations in the bovine growth hormone (bGH)/insulin-like growth factor (IGF)-I axis induced by plane of nutrition and bGH treatment of heifer calves caused variations in serum-induced proliferation of C2C12 myoblasts. Serum was obtained from two groups each of six heifer calves (195 +/- 8 kg) before (d -1) and after treatment with 15 mg/day of bGH for 6 days (d 6) fed either a low (GHL) or a high plane (GHH) of nutrition. Preceding the experiment all 12 heifer calves were fed at the low plane of nutrition. At d 6, serum concentrations of insulin and IGF-I were increased while that of IGF-binding proteins (IGFBP)-2 was decreased in GHH, but unchanged in GHL calves. Serum-induced proliferation of C2C12 myoblasts, was elevated at d 6 by GHH treatment. Especially human IGFBP-3 but also bovine IGFBP-2 added to cell cultures inhibited the rate of proliferation of C2C12 myoblasts stimulated by human IGF-I. The present results showed that GH treatment causes changes in the GH/IGF axis, which leads to changes in serum-induced growth of C2C12 muscle cells dependent on the plane of nutrition that mimic in vivo effects of GH treatment, which indicate an endocrine contribution of the IGF system. However, drawbacks of this suggestion are discussed.

Heifer Production on Rangeland and Seeded Forages in the Northern Great Plains

Integrating use of seeded perennial cool-season grass pastures with native rangeland can increase available forage and provide a high plane of nutrition for grazing livestock. Our objective was to compare performance of yearling beef heifers grazing native rangeland with those grazing an integrated system that included seeded forages. Twice-replicated, 3-ha pastures seeded to either ‘Rosana’ western wheatgrass ( Pascopyron smithii [Rydb.] A. Love), ‘Luna’ pubescent wheatgrass ( Elytrigia intermedia [Host] Nevski), or ‘Hycrest’ crested wheatgrass ( Agropyron cristatum [L.] Gaertn. ssp. desertorum [Fisch. ex Link] A. Love) were grazed in spring, whereas twice-replicated, 3.24-ha pastures seeded to either ‘Alkar’ tall wheatgrass ( Thinopyrum ponticum [Podp.] ZW Liu & RC Wang), ‘NewHy’ hybrid wheatgrass ( Elymus hoffmannii KB Jensen & KH Asay), ‘Bozoisky’ Russian wildrye ( Psathyrostachys juncea [Fisch.] Nevski.), or ‘Prairieland’ Altai wildrye ( Leymus angustus [Trin.] Pilger) were grazed in autumn. Native rangeland was grazed during summer in the integrated system and spring, summer, and autumn in the rangeland treatment. Heifers exhibited greater weight gains on seeded pastures than on native rangeland in spring and autumn of most years. In 2 out of 3 years, heifers that grazed native rangeland during spring gained more ( P = 0.012 for gain head −1 and P = 0.021 for gain head −1 day −1 ) while grazing native rangeland during summer than heifers that grazed seeded pastures in spring. Spring + summer gains averaged (mean ± SE) 0.56 ± kg·head −1 ·d −1 and 73.1 ± kg·head −1 . Livestock managers need to consider their livestock marketing and management strategies when using seeded pastures for seasonal grazing. La integración del uso de praderas sembradas de zacates perennes de estación fría con pastizal nativo puede incrementar el forraje disponible y proveer un buen plano nutricional para el ganado en apacentamiento. Nuestro objetivo fue comparar el comportamiento productivo de vaquillas de ganado de carne de año apacentando un pastizal nativo con vaquillas apacentando un sistema integrado que incluía forrajes sembrados. Praderas de 3 ha, repetidas dos veces, sembradas con “Western wheatgrass” ( Pascopyron smithii [Rydb.] A. Love) variedad ‘Rosana’ y “Pubescent wheatgrass” ( Elytrigia intermedia [Host] Nevski) variedad ‘Luna’ o con “Crested wheatgrass” ( Agropyron cristatum [L.] Gaertn. ssp. desertorum [Fisch. ex Link] A. Love) variedad ‘Hycrest’ fueron apacentadas en primavera, mientras que praderas de 3.24 ha, repetidas dos veces, sembradas con “Tall wheatgrass” ( Thinopyrum ponticum [Podp.] ZW Liu & RC Wang) variedad ‘Alkar’, “Hybrid wheatgrass” ( Elymus hoffmannii KB Jensen & KH Asay) variedad ‘NewHy’, “Russian wildrye” ( Psathyrostachys juncea [Fisch.] Nevski.) variedad ‘Bozoisky’ o con “Altai wildrye” ( Leymus angustus [Trin.] Pilger) variedad ‘Prairieland’ fueron apacentadas en otoño; en el sistema integrado, el pastizal nativo fue apacentado en verano y en el tratamiento de solo pastizal se apacentó en primavera, verano y otoño. En la mayoría de los años, las vaquillas mostraron mayores ganancias de peso en las praderas sembradas que los obtenidos en el pastizal nativo en primavera y otoño. En 2 de 3 años, la vaquillas que apacentaron el pastizal nativo durante la primavera, ganaron más peso ( P = 0.012 para ganancia cabeza −1 y P = 0.021 para la ganancia cabeza −1 dia −1 ) cuando apacentaban el pastizal en verano que las vaquillas que apacentaron en primavera las praderas sembradas. Las ganancias de primavera + verano promediaron 0.56 ± kg·cabeza −1 ·d −1 y 73.1 ± kg·cabeza −1 . Cuando utilicen praderas sembradas para el apacentamiento estacional, los manejadores de ganado necesitan considerar su mercadeo del ganado y estrategias de manejo.

The effect of limited overfeeding during growth on muscle characteristics: A pig model

Energy restriction affects the hypothalamus, leading to a decrease in production of reproductive and thyroid hormones. A decrease in reproductive hormones affects fertility and a decrease in thyroid hormones affects muscle metabolism. A pig model has been used to determine that reproductive function is negatively affected if the normal practice of overfeeding is limited during the late luteal phase of the estrous cycle. We used a sub-set of pigs from this study to examine effects of limiting overfeeding on thyroid hormones and skeletal muscle (i.e. maximal enzyme activities, and muscle fibre characteristics). Eighteen rapidly growing gilts were randomized into three groups: 1) feeding a high plane of nutrition throughout the first 15 days of the estrous cycle; 2) limited overfeeding (25% below the first group) for first 7 days of the estrous cycle (early luteal phase), followed by a high plane of nutrition for days 8-15 (late luteal phase); and 3) high plane of nutrition throughout the first 7 days of the estrous cycle, followed by 8 days of limited overfeeding. Muscle biopsies were collected from the triceps brachii, and blood samples were collected for assessment of thyroid hormones at days 0 (baseline), 8 and 16. There was no effect of limited overfeeding on thyroid hormones, maximal enzyme activities, muscle fibre area or muscle fibre type. Limited overfeeding in rapidly growing pigs does not affect thyroid hormone status or muscle characteristics.

Oocyte–somatic cell–endocrine interactions in pigs

Oocyte–somatic cell communication is bi-directional and essential for both oocyte and follicular granulosa and theca cell function and development. We have shown that the oocyte secretes factors that stimulate porcine granulosa cell proliferation in serum-free culture, and suppress progesterone production, thereby preventing premature luteinisation. Possible candidates for mediating some of these effects are the bone morphogenetic proteins (BMPs) that belong to the transforming growth factor β family. They are emerging as a family of proteins critical for fertility and ovulation rate in several mammals, and they are expressed in various cell types in the ovary. We have evidence for a functional BMP system in the porcine ovary and BMP receptors are present in the egg nests in the fetal ovary and in the granulosa cells, oocytes and occasional theca cells throughout subsequent development. In addition to paracrine interactions in the ovary, the porcine oocyte and its developmental potential can also be influenced by nutritional manipulation in vivo. We have demonstrated that feeding a high plane of nutrition to gilts for 19 days prior to ovulation increased oocyte quality compared to control animals fed a maintenance diet, as determined by oocyte maturation in vitro. This was associated with a number of changes in circulating reproductive and metabolic hormones and also in the follicular fluid in which the oocyte is nurtured. Further studies showed a similar increase in prenatal survival on Day 30 of gestation, demonstrating a direct link between oocyte quality/maturation and embryo survival. Collectively, these studies emphasise the importance of the interactions that occur between the oocyte and somatic cells and also with endocrine hormones for ovarian development, and ultimately for the production of oocytes with optimal developmental potential.

Effect of plane of nutrition on seasonality of reproduction in Spanish Payoya goats

The aim of this study was to determine if there is a seasonal pattern of sexual activity in female Payoya goats and if this seasonality could be modulated by nutrition. During the experimental period of 20 months, 43 non-pregnant adults goats were penned under natural photoperiod at latitude 37°15′N. At the onset of the experiment, the animals were allocated to three experimental groups differing in the level of nutrition and whether the animals were entire or ovariectomized does. The high nutrition group (H, n = 16 entire does) receiving 1.5 times maintenance requirements. The low nutrition group (L, n = 16 entire does) and an ovariectomized and oestradiol treated group (OVX, n = 11 ovariectomized does) received a diet supporting their maintenance requirements. The groups were balanced for live weight (LW) and body condition score (BCS) at the beginning of the study. In entire goats, oestrus was tested daily using aproned males, ovulation rate was assessed by laparoscopy 7 days after identification of oestrus and plasma samples were obtained twice per week for progesterone assay. OVX goats were isolated from the other groups and bucks, plasma samples were assayed twice per week for LH and there were four intensive sampling periods during the year to determine LH pulsatility. LW and BCS were recorded for all animals once a week. A clear circannual cycle in live weight change was observed in all experimental groups, being relatively stable or slightly decreasing in summer and autumn and increasing during winter and spring. The effect of exposure to high (H) rather than low (L) nutrition was to cause earlier onset of ovarian activity (5 versus 17 August; P < 0.05), and expression of oestrous (16 August versus 2 September; P < 0.01) and later cessation of reproductive activity (ovulation 11 February versus 17 January; P < 0.01). Consequently, seasonal anoestrus was 32 days shorter in does on the higher plane of nutrition ( P < 0.01). The seasonality of reproductive activity was confirmed in the OVX does, with reduced LH concentrations during spring and summer, and increased LH concentrations in autumn and winter. There was no effect of nutrition on ovulation rate. These results demonstrate that the female Payoya goat exhibits marked reproductive seasonality which is modulated by nutrition but possibly not ovulation rate.

Relationship between sire estimated breeding values and the meat and eating quality of meat from their progeny grown on two planes of nutrition

The meat of 140 female lambs was examined. These lambs were sired by 9 Poll Dorset sires (3 selected for growth, 3 for muscling and 3 control) and fed either a low or high plane of nutrition from birth to slaughter. All carcasses were electrically stimulated and portions of M. longissimus thoracis et lumborum (loin) aged for 5 days before freezing. Subsequently, 10 consumers tested each portion for eating quality traits. A portion of the same muscle from the opposing side of the carcass was divided into 3 sections and aged for either 1, 3 or 5 days and then used to measure shear force (objective tenderness). Portions of the M. semimembranosus (topside) were also aged for 3 or 5 days and subjected to shear testing. Low plane animals produced tougher loins (based on shear force). As ultimate pH increased, shear force of the loin increased for low plane animals, while for high plane animals there was no such effect. This latter group had significantly lower ultimate pH values in all 3 muscles tested. Plane of nutrition had the greatest effect on topside shear force with low plane lambs producing tougher topsides. As ultimate pH increased, the topsides became tougher and as expected ageing improved the tenderness. There was no effect of sire EBVs (estimated breeding values) on shear force or objective meat quality traits apart from loin lightness which increased as the EBV for post-weaning weight (PWWT) increased and intramuscular fat in the loin which decreased as sire EBV for post-weaning muscle depth (PEMD) increased. Plane of nutrition did not have a significant effect on eating quality attributes as assessed by consumers. There was, however, an effect of sire EBV for muscling (PEMD) on tenderness, juiciness, flavour and overall liking, such that increased EBV led to decreased scores for the sensory traits. The findings suggest selection of sires for increasing PEMD will have a detrimental affect on the eating quality of their progeny, but this will not be reflected in shear force values or other objective meat quality traits apart from intramuscular fat. The effects of a low plane of nutrition on eating quality were minimal and largely controlled by the use of best practice processing, but were evident for a number of meat quality traits.

Heifer Production on Rangeland and Seeded Forages in the Northern Great Plains

Integrating use of seeded perennial cool-season grass pastures with native rangeland can increase available forage and provide a high plane of nutrition for grazing livestock. Our objective was to compare performance of yearling beef heifers grazing native rangeland with those grazing an integrated system that included seeded forages. Twice-replicated, 3-ha pastures seeded to either ‘Rosana’ western wheatgrass (Pascopyron smithii [Rydb.] A. Love), ‘Luna’ pubescent wheatgrass (Elytrigia intermedia [Host] Nevski), or ‘Hycrest’ crested wheatgrass (Agropyron cristatum [L.] Gaertn. ssp. desertorum [Fisch. ex Link] A. Love) were grazed in spring, whereas twice-replicated, 3.24-ha pastures seeded to either ‘Alkar’ tall wheatgrass (Thinopyrum ponticum [Podp.] ZW Liu RC Wang), ‘NewHy’ hybrid wheatgrass (Elymus hoffmannii KB Jensen KH Asay), ‘Bozoisky’ Russian wildrye (Psathyrostachys juncea [Fisch.] Nevski.), or ‘Prairieland’ Altai wildrye (Leymus angustus [Trin.] Pilger) were grazed in autumn. Native rangeland was grazed during summer in the integrated system and spring, summer, and autumn in the rangeland treatment. Heifers exhibited greater weight gains on seeded pastures than on native rangeland in spring and autumn of most years. In 2 out of 3 years, heifers that grazed native rangeland during spring gained more (P = 0.012 for gain head-1 and P = 0.021 for gain head-1 day-1) while grazing native rangeland during summer than heifers that grazed seeded pastures in spring. Spring + summer gains averaged (mean +/- SE) 0.56 +/- 0.01 kg head-1 d-1 and 73.1 +/- 1.6 kg head-1. Livestock managers need to consider their livestock marketing and management strategies when using seeded pastures for seasonal grazing.

Johne's Disease

Mycobacterium avium subspecies paratuberculosis (MAP) is an acid fast intracellular bacillus that infects ruminants worldwide. The disease is characterized by chronic diarrhea and weight loss, despite a good appetite, even on a high plane of nutrition. The disease has a significant economic impact on both the dairy and beef cattle industry in the USA. Control of the disease is difficult due to fecal shedding of the sub-clinical animal and much effort has been put into identifying the disease in the early stages. Currently there are no reliable tests for detecting early infection. The ELISA test has been used in many seroprevalence studies. This method offers the advantage of availability of results in a short period of time and comparable sensitivity to the fecal culture. Sensitivity of the test is approximately 40-50%, but may vary from 15-87% depending on the animal's stage of the infection. Higher sensitivities are obtained from heavy shedders of the bacteria. The specificity of the current ELISA test is 99%. In 1990 Braun et al reported ELISA results of a 1986-1987 survey of Florida cattle indicating a prevalence of 8.6% in beef cattle and 17.1 % in dairy cattle. The high prevalence in that study warranted the re-evaluation of the prevalence of Johne's disease in the state. The objective of this study was to estimate the apparent prevalence of MAP antibodies in Florida cattle from samples submitted to the Florida State Veterinary Diagnostic Laboratory.

EFFECT OF SIRE TYPE AND PLANE OF NUTRITION ON LAMB LOIN SHEAR FORCE, MYOFIBRILLAR FRAGMENTATION INDEX AND CALCIUM CONCENTRATION

ABSTRACTThe tenderness, myofibrillar fragmentation (MF) and calcium concentration of 140 female lambs sired by Poll Dorset sires of 3 sire types (3 selected for growth, 3 selected for muscling and 3 control) and fed either a low or high plane of nutrition from birth to slaughter was examined. Carcasses were electrically stimulated and portions of m. longissimus thoracis et lumborum (loin) aged for 1,3 or 5 days. Sire type had no effect on shear force values or MF values. Low plane animals produced tougher loins at each aging period with a greater reduction in shear force during aging in low plane animals. MF values increased with aging indicative of increased degradation, but were lower in low plane animals consistent with the increased toughness in this group. There was no effect of sire type on ‘free‘ calcium concentration in loin muscle, but low plane lambs had a higher calcium concentration. The concentration of free calcium increased with aging. The findings suggest that plane of nutrition can influence loin tenderness and this is reflected in reduced myofibril degradation, but sire type effects are not important as tested in this work.

The effect of rearing regime on the development of the mammary gland and claw abnormalities in high genetic merit Holstein-Friesian dairy herd replacements

AbstractOne hundred and eight high genetic merit Holstein-Friesian heifers were used to determine the effects of rearing regime on the development of the mammary gland and claw abnormalities. Heifers were allocated to one of four rearing regimes at 7 weeks of age and slaughtered at 18 (s.d.0.7) months of age; mating commenced at 14 months of age. Treatment 1 heifers were reared to calve at 540 kg and treatments 2, 3 and 4 heifers reared to calve at 620 kg. Treatment 1 and 2 heifers were offered grass silage-based diets during the winter and grass-based diets during the summer; treatment 2 heifers received additional concentrates. Treatment 3 heifers were offered a straw/concentrate diet during the winter and a grass-based diet during the summer. Treatment 4 heifers received the same winter diets as treatment 3 but were housed and offered a straw/concentrate diet in summer. Increasing plane of nutrition increased the weight of dissected udder fat (P &lt; 0.01), but had no effect on the weight or chemical composition of dissected udder parenchyma. Offering straw- compared with silage-based diets reduced fat deposition in the udder (P &lt; 0.01) and increased the proportion of parenchyma in the udder (P &lt; 0.01). Keeping heifers housed during the first summer and offering straw-based diets relative to those turned out to grass had no effect on weight of fat although there was a tendency towards a reduction in the proportion of parenchyma in the udder (P &lt; 0.06). Heifers reared on a low plane of nutrition had lower values for heel height (P &lt; 0.001), lateral claw length (P &lt; 0.001) and heel erosion scores (P &lt; 0.01). A higher plane of nutrition also increased live weight/sole area although this was only significantly higher for treatment 3 (P &lt; 0.05) compared with treatment 1 heifers. Housing heifers in the first summer increased the incidence of feet lesions in the white line area and solear area relative to turning heifers out to grass in the first summer (P &lt; 0.05).

Experimental infection of house finches with Mycoplasma gallisepticum.

Mycoplasma gallisepticum (MG) has caused an endemic upper respiratory and ocular infection in the eastern house finch (Carpodacus mexicanus) after the epidemic first described in 1994. The disease has been studied by a number of investigators at a population level and reports describe experimental infection in group-housed MG-free house finches. Because detailed observation and evaluation of individual birds in group-housed passerines is problematic, we studied individually housed house finches that were experimentally inoculated with the finch strain of MG in a controlled environment. To accomplish this, a study was conducted spanning the period of November 2001-April 2002 with 20 MG-free (confirmed by the rapid plate agglutination assay and polymerase chain reaction [PCR] assay) eastern house finches captured in the Cayuga Basin area of central New York (USA) in the summer of 2001. After a period of acclimatization and observation (12 wk), 20 finches were inoculated with a 0.05-ml aliquot of MG (3.24 x 10(5) colony-forming units/ml) via bilateral conjunctival sac instillations. Two additional finches acted as controls and were inoculated in the same manner with preservative-free sterile saline solution. After inoculation, all finches except the controls exhibited clinical signs of conjunctivitis within 2-6 days. The progression of the disease was evaluated by several methods, including PCR, behavioral observations, and physical examination including eye scoring, body weight, and body condition index. Over a period of 21 wk, MG-infected finches developed signs of disease and recovered (80%), developed signs of disease and progressed to become chronically infected (15%), or died (5%). We hypothesize that the high survival rate and recovery of these finches after infection was associated with the use of controlled environmental conditions, acclimatization, a high plane of nutrition, and low stocking (housing) density, all of which are factors documented to be important in the outcome of MG infections in domestic poultry and other species.

Demographic Characteristics of a Reintroduced Elk Population in Kentucky

We used radiotelemetry and field observations to study survival and reproduction of 718 reintroduced elk (Gervus elaphus) in eastern Kentucky, USA, from 1997 to 2001. Capture-related injuries accounted for 49% of the transit and post-release mortality. Annual survival was high across all age and sex classes, and ranged from 0.90 (adult females) to 0.97 (yearling females). Calving rates increased from 66% in 1998 to 92% in 2000. A high nutritional plane may explain the relatively high reproduction among females bred as yearlings, consecutive-year pregnancies, and twinning. Such high survival and reproductive rates are characteristic of colonizing ungulate populations in areas devoid of predators and competitors. Future research should focus on Kentucky-born calves to more accurately determine the effects of meningeal worm (Prelaphostrongylus tenuis) and other factors on recruitment, colonization, and population establishment.

Effect of Level of Feeding on the Performance of Crossbred Cows during Pre- and Post-partum Periods

The study was undertaken to see the effect of elevated feeding during pre-partum or pre- as well as post-partum period on the productive and reproductive performance of crossbred cows. The experiment lasted for 60 d pre-partum to 120 d post-partum. Eighteen dry pregnant crossbred cows divided into three equal groups were fed either as per NRC feeding standard (C) or 20% above NRC during 60 d pre-partum (T1) or fed 20% above NRC during both 60 d pre-partum to 120 d post-partum (T2) period. During pre- partum period body weight gain was significantly (p≤0.05) higher in T1 and T2 groups than that of control group. The animals fed at higher plane of nutrition (T1 and T2) took significantly lesser time for complete relaxation of pelvic muscles, act of calving and for expulsion of placenta than that of control group. Moreover, such cows delivered 2 to 3 kg heavier calves as compared to normal fed dams. During post-partum period, the average daily milk yield was significantly higher in T2 group than that in T1 and control groups. The peak yield was significantly higher in T2 group, it took longer time to reach peak production but it was more persistent in this group as compared to T1 and control groups. Average milk fat, solids-not-fat (SNF) and total solids were significantly higher in T1 and T2 groups as compared to control group. Body weight losses incurred during early lactation were not even compensated by end of 4th month of lactation in C and T1 groups whereas the animals in T2 group gained 2.0 kg. The 1st post-partum estrus and conception rate were better in high fed groups (T1 and T2) than that of control group. The returns over feed cost of milk production were higher in T2 group followed by T1 and control groups indicating the advantage of elevated feeding during pre- and post-partum periods. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 12 : 1749-1754)