Blood serum tocopherol levels in calves born from cows winter fed hay or grass silage.

Blood serum tocopherol was determined in 44 calves born in the spring from cows that had been fed either timothy grass silage or timothy hay produced in Norther Ontario. On all sampling dates (at birth and at eight, 21, 35 and 60 days of age), calves from the silage group had higher average tocopherol levels than those from the hay group. Studies on serum tocopherol distribution in cows and their calves obtained 60 days after birth from the silage group showed that alpha-tocopherol averaged 85% and beta + gamma-tocopherols 12%. Only trace quantities of delta-tocopherol were detected in the serum of cows but none in those of calves.     

不同全株玉米青贮饲喂量对妊娠期母牛体况、血液指标及后代犊牛的影响

试验旨在研究全株玉米青贮饲喂量及精粗饲料配比对妊娠期母牛体况、血液指标及后代犊牛的影响。选用40头体重相近、2岁、1胎的妊娠期7个月左右的西门塔尔母牛,随机分为4组,每组10头,试验期3个月。Ⅰ组每头每天饲喂全株玉米青贮14 kg、燕麦秸1 kg、精料补充料3 kg,Ⅱ组每头每天饲喂全株玉米青贮19 kg、燕麦秸1 kg、精料补充料1 kg,Ⅲ组每头每天饲喂全株玉米青贮19 kg、燕麦秸2 kg,Ⅳ组每头每天饲喂全株玉米青贮22 kg、燕麦秸1 kg。产犊后各组母牛统一更换为泌乳料,母牛带犊哺乳,6月龄断奶。结果表明:Ⅳ组的干物质摄入量低于Ⅰ组(P<0.05);Ⅲ组和Ⅳ组的氮摄入量低于其他组(P<0.01),Ⅰ组最高(P<0.01);Ⅲ组的纤维摄入量高于其他组(P<0.01);各组体况评分无差异;妊娠期7月末,Ⅳ组血液锰含量低于其他组(P<0.05);妊娠期9月末,Ⅲ组和Ⅳ组的血清尿素氮含量低于其他组(P<0.01);Ⅳ组母牛所产犊牛的胸围低于Ⅰ组和Ⅱ组(P<0.05),且有3头因生长缺陷被淘汰;6月龄时,各组犊牛体况指标无差异。综上,推荐肉牛能繁母牛妊娠后期每日提供全株玉米青贮19 kg、燕麦秸1~2 kg、精料补充料0~1 kg。     

Feeding dairy calves and replacement heifers in South-western Sweden: a survey

Daily feed rations, their nutrient contents and live weight gains were recorded for calves and replacement heifers from birth to calving in 122 Swedish dairy herds. Preweaned calves were fed whole milk (45% of the herds), milk replacer alone or milk replacer combined with whole milk. Calf starters were the most frequently used concentrates for preweaned calves, whereas grain dominated for weaned calves and heifers. Grain was supplemented with protein concentrates until 6 months of age and at calving. Grass/clover hay was the dominant forage for preweaned calves, whereas grass/clover silage alone or in combination with hay was the most common forage for calves and replacement heifers from 6 months of age. Heifers grazed semi-natural grasslands, leys or a combination of semi-natural grasslands and leys in 33, 15 and 52% of the herds, respectively. According to Swedish recommendations, calves in a majority of the herds were fed too low concentrations of crude protein from weaning to 6 months of age and calves were fed too low a metabolizable energy content inadequate for a daily weight gain of 700 g at weaning. Median live weight gain from birth to calving was only 567 g per day. Correct feed ration formulations and strategic grazing management could be means to increase weight gain and hence to decrease rearing costs of calves and replacement heifers in Swedish dairy herds.     

苜蓿青贮料替代苜蓿青干草对奶牛生产性能及乳品质的影响

试验旨在探讨苜蓿青贮料替代不同比例苜蓿青干草对奶牛生产性能、乳品质、营养物质表观消化率、血液生化指标及经济效益的影响。选取体重、产奶量、胎次相近的健康泌乳中期中高产中国荷斯坦奶牛15头,随机分为3组,每组5个重复,每个重复1头牛。对照组饲喂4.0 kg苜蓿青干草,试验A、B组分别用4.4,8.8 kg苜蓿青贮料代替2.0和4.0 kg等干物质的苜蓿青干草,正试期64 d。结果表明,1)各组间干物质采食量差异不显著(P>0.05),B组产奶量显著低于对照组(P<0.05),A组与对照组、B组间差异不显著(P>0.05); 2)用50%,100%的苜蓿青贮料替代等干物质的苜蓿青干草,其乳蛋白、乳脂率、乳糖均有所改善,但只有B组的乳脂率显著高于对照组(P<0.05),其余指标各组间差异均不显著(P>0.05);3)A、B组与对照组的中性洗涤纤维表观消化率、钙表观消化率无显著性差异(P>0.05),A、B组间粗蛋白和磷表观消化率差异不显著(P>0.05),但是粗蛋白表观消化率均显著低于对照组、磷表观消化率均显著高于对照组(P<0.05);4)苜蓿青贮料替代苜蓿青干草其血清总蛋白、白蛋白、血尿素氮、血糖、二氧化碳结合力等指标没有显著性改变(P>0.05);5)试验A、B组经济效益均有所增加,其中A组的净增收益最高,为0.61元/(头·d)。综上,用4.4 kg苜蓿青贮料代替2.0 kg苜蓿青干草对中高产奶牛是适宜的,能提高其生产性能,改善乳品质,增加收益。     

Effects of dam nutrition on growth and reproductive performance of heifer calves

A 3-yr study was conducted with heifers (n = 170) whose dams were used in a 2 x 2 factorial arrangement of treatments to determine the effects of late gestation (LG) or early lactation (EL) dam nutrition on subsequent heifer growth and reproduction. In LG, cows received 0.45 kg/d of a 42% CP supplement (PS) or no supplement (NS) while grazing dormant Sandhills range. During EL, cows from each late gestational treatment were fed cool-season grass hay or grazed sub-irrigated meadow. Cows were managed as a single herd for the remainder of the year. Birth date and birth weight of heifer calves were not affected (P > 0.10) by dam nutrition. Meadow grazing and PS increased (P = 0.02; P = 0.07) heifer 205-d BW vs. feeding hay and NS, respectively. Weight at prebreeding and pregnancy diagnosis were greater (P < 0.04) for heifers from PS dams but were unaffected by EL nutrition (P > 0.10). There was no effect (P > 0.10) of LG or EL dam nutrition on age at puberty or the percentage of heifers cycling before breeding. There was no difference (P > 0.10) in pregnancy rates due to EL treatment. Pregnancy rates were greater (P = 0.05) for heifers from PS dams, and a greater proportion (P = 0.005) of heifers from PS dams calved in the first 21 d of the heifers' first calving season. Nutrition of the dams did not influence (P < 0.10) heifers' average calving date, calving difficulty, and calf birth weight during the initial calving season. Weight at the beginning of the second breeding season was greater (P = 0.005) for heifers from PS dams but was not affected by maternal nutrition during EL (P > 0.10). Dam nutrition did not affect (P > 0.10) heifer ADG or G:F ratio. Heifers from PS dams had greater DMI (P = 0.09) and residual feed intake (P = 0.07) than heifers from NS cows if their dams were fed hay during EL but not if their dams grazed meadows. Heifers born to PS cows were heavier at weaning, prebreeding, first pregnancy diagnosis, and before their second breeding season. Heifers from cows that grazed meadows during EL were heavier at weaning but not postweaning. Despite similar ages at puberty and similar proportions of heifers cycling before the breeding season, a greater proportion of heifers from PS dams calved in the first 21 d of the heifers' first calving season, and pregnancy rates were greater compared with heifers from NS dams. Collectively, these results provide evidence of a fetal programming effect on heifer postweaning BW and fertility.     

Indigestion in Young Calves. V. The Influence of Grass Silage and Fine Hay

In an experiment with 24 young calves, lasting 45 days, all were fed a high lactose milk replacer causing some diarrhoea. Eight calves received grass silage and 8 fine hay in addition, while 8 received no solid supplement to the milk replacer (NS). Somewhat more (P < 0.05) dry matter was ingested from silage than hay. Weight gain was similar on the 2 supplements and much greater (P < 0.001) than on NS. Both silage and fine hay reduced (P < 0.01) the frequency of diarrhoea, approximately to the same extent. Further, silage or hay gave higher pH (P = 6.0.01 and 0.02, respectively) and less gram positive cocci and rods in the rumen fluid, better developed ruminai papillae and heavier (P < 0.01) empty reticulo-rumens than NS. Some calves fed silage had ulcers in the rumen, the same having occurred on fine hay in earlier experiments, but not in the present one. Althogether, the 2 roughages gave very similar results.     

Composition and Nutrient Deficiencies of Arkansas Forages for Beef Cattle

A database was compiled to determine the nutrient composition, variability, and nutrient deficiencies of 11,592 forage samples (10,246 hay, 1,001 pasture, and 345 silage) collected from 1985 to 1999. Samples were analyzed for 1 to 15 nutrients: DM, N, ADF, NDF, P, K, Ca, Mg, Na, S, Fe, Mn, Zn, Cu, and Se. Mean (±SD) CP and TDN levels (% DM) of bermudagrass, fescue, and mixed grass (blends of bermudagrass, fescue, orchardgrass, ryegrass, and cheat) hays were 12.4 ± 3.5, 60.0± 6.2; 11.2± 3.0, 53.8± 4.7; and 11.1 ± 3.1, 52.9± 4.7, respectively. For beef cows and calves, TDN was deficient in a greater percentage of hays (P < 0.05) than was CP. Bermudagrass hays contained greater levels of CP and TDN than fescue or mixed grass hays (P < 0.05). Fescue and mixed grass hays did not differ (P > 0.05) in CP, ADF, NDF, or TDN concentrations. Only 6 to 10% of the hays analyzed for Na contained adequate levels for beef cows and calves. Selenium, Cu, and Zn were deficient in 62, 52, and 41% of the hay samples, respectively. For lactating beef cows, a lesser percentage of the hays were deficient in P (16%), Ca (7%), Mg (30%), and S (8%). Iron, Mn, and K were deficient in 2% or less of the hays. Bermudagrass, corn, and sorghum-sudan silages contained greater (P < 0.05) levels of TDN than silages composed of fescue, mixed grass, ryegrass, sorghum silage types, or wheat. With the exception of bluestems and orchardgrass, the pasture samples contained greater concentrations of CP and TDN than the same forage species harvested as hay. In general, forages were highly variable in nutrient content, and most hays were deficient in one or more nutrients for beef cattle.     

Effects of prepartum energy intake on steroids during late gestation and on cow and calf performance

At 50 d prior to predicted calving, 37 multiparous Angus cows were grouped by sire of mating, age and weight of cow and placed on either a high energy (HE, n = 19) diet or a moderate energy (ME, n = 18) diet. Objectives were to determine the effect of prepartum nutrition on: prepartum serum concentrations of estrone (E1), estrone sulfate (E1SO4) and progesterone (P4); pre- and postpartum cow body weight changes; calf birth weight and cow and calf postpartum performance. The ME cows were group-fed Coastal bermudagrass hay ad libitum and dormant pasture; HE cows were group-fed 2.7 kg ground corn X head-1 X d-1 in addition to the ME treatment. Both groups were combined and fed identically after calving. Cows fed HE were heavier (P less than .01) than cows fed ME at d 10 prepartum and their calves were heavier (P less than .05) at birth and weaning than calves from cows fed ME. Serum E1 concentrations were not significantly different between groups, but serum E1SO4 was higher (P less than .01) at d 10 prepartum in ME cows compared with HE cows. Serum P4 concentrations of ME cows were higher (P less than .05) than those of HE cows. Cow body weights were greater (P less than .01) for the HE group than for the ME group during the first 6 mo postpartum. Cow rebreeding performance was identical for both groups.     

Evaluation of histopathologic and physiologic changes in cows having premature births after consuming Ponderosa pine needles

Premature calving, typified by early expulsion (17 to 43 days) of weak or dead calves and accompanied by retained placentas, was induced in 8 of 9 pregnant cows fed a mixture of Ponderosa pine needles and alfalfa hay. Five control cows of comparable gestation age fed only alfalfa hay maintained normal pregnancies until they were euthanatized at the time the pine needle-treated cows were producing premature calves. Serum specimens from all cows were assayed for progesterone concentration and ovaries and placentomes were examined for histopathologic changes. There were no bacterial, fungal, chlamydial, or viral agents determined to be associated with the premature births. Serum progesterone concentration in the treated cows decreased progressively and were 0.4 to 1.5 ng/ml at the time of premature calving. Histopathologic changes were evident in the placenta and corpora lutea of treated cows only. The number of binucleate trophoblastic giant cells in placentomes was less than normal and the number of necrotic luteal cells in corpora lutea was greater than normal.     

Effects of feeding and animal performance on nitrogen, phosphorus and potassium excretion by Holstein cows

Thirty‐four Holstein dry cows and 16 lactating cows were used in balance trials to identify the effects of feeding and animal performance on nitrogen (N), phosphorus (P) and potassium (K) excretion by dairy cows, and to develop prediction models for these excreta. Orchard grass silage, corn silage, alfalfa silage or timothy hay were offered to dry cows. Orchard grass silage or alfalfa silage, and concentrates were offered to lactating cows. In the statistical analysis, the independent variables were bodyweight (kg), dry matter (DM) intake (kg/day), milk yield (for lactating cows only, kg/day), water intake (free water plus water in feed, kg/day), intake (g/day) of N, P and K and dietary contents (% of DM) of crude protein, P and K. The dependent variables were N, P and K excretion (g/day) in feces and urine. In both dry and lactating cows, intake of N, P and K had large effects on corresponding excretion. The results indicated that a decrease in the intake of N, P and K could decrease the corresponding excretion. Further research by path analysis showed that K intake positively affected urinary N excretion in dry cows indirectly, through water intake and urine volume.     

Effects of supplementary selenium source on the performance and blood measurements in beef cows and their calves

On December 2, 1999, 120 pregnant cows were weighed, their body condition scored, and then sorted into six groups of 20 stratified by BCS, BW, breed, and age. Groups were assigned randomly to six, 5.1-ha dormant common bermudagrass (Cynodon dactylon [L.] Pers.) pastures for 2 yr to determine the effects of supplemental Se and its source on performance and blood measurements. During the winter, each group of cows had ad libitum access to bermudagrass/dallisgrass (Paspalum dilatatum Poir.) hay plus they were allowed limited access (1 to 4 d/wk) to a 2.4-ha winter-annual paddock planted in half the pasture. Treatments were assigned randomly to pastures (two pastures per treatment), and cows had ad libitum access to one of three free-choice minerals: 1) no supplemental Se, 2) 26 mg of supplemental Se from sodium selenite/kg, and 3) 26 mg of supplemental Se from seleno-yeast/kg (designed intake = 113 g/cow daily). Data were analyzed using a mixed model; year was the random effect and treatment was the fixed effect. Selenium supplementation or its source had no effect (P > or = 0.19) on cow BW, BCS, conception rate, postpartum interval, or hay DMI. Birth date, birth weight, BW, total BW gain, mortality, and ADG of calves were not affected (P > 0.20) by Se or its source. Whole blood Se concentrations and glutathione peroxidase (GSH-Px) activity at the beginning of the trial did not differ (P > or = 0.17) between cows receiving no Se and cows supplemented with Se or between Se sources. At the beginning of the calving and breeding seasons, cows supplemented with Se had greater (P < 0.01) whole blood Se concentrations and GSH-Px activities than cows receiving no supplemental Se; cows fed selenoyeast had greater (P < or = 0.05) whole blood Se concentrations than cows fed sodium selenite, but GSH-Px did not differ (P > or = 0.60) between the two sources. At birth and on May 24 (near peak lactation), calves from cows supplemented with Se had greater (P < or = 0.06) whole blood Se concentrations than calves from cows fed no Se. At birth, calves from cows fed seleno-yeast had greater (P < or = 0.05) whole blood Se concentrations and GSH-Px activities than calves from cows fed sodium selenite. Although no differences were noted in cow and calf performance, significant increases were noted in whole blood Se concentrations and GSH-Px activities in calves at birth as a result of feeding of seleno-yeast compared to no Se or sodium selenite.     

Calving system and weaning age effects on cow and preweaning calf performance in the Northern Great Plains

A 3-yr study evaluated late winter (Feb), early spring (Apr), and late spring (Jun) calving systems in conjunction with varied weaning strategies on beef cow and calf performance from Northern Great Plains rangelands. Crossbred cows were randomly assigned to one of three calving systems (on average n= 168.calving system(-1).yr(-1)) and one of two weaning times (Wean 1, 2) within each calving system. The Feb and Apr calves were weaned at 190 and 240 d of age, whereas Jun calves were weaned at 140 and 190 d of age. Breeding by natural service occurred in a 32-d period that included estrous synchronization. Cows were managed throughout the year as appropriate for their calving season. Quantity and quality of hay and supplements were provided based on forage and weather conditions, physiological state of the cows, and available harvested feed resources within a year. After weaning, two-thirds of the early weaned steers were fed in confinement in Montana, and one-third were shipped to Oklahoma and were grazed or fed forage. One-half of the early weaned heifers grazed seeded pastures, and the other half was fed in confinement. Early weaned calves were weighed on approximately the same day as late-weaned calves. Birth weight and overall rate of gain from birth to weaning did not differ for calves from the three calving systems. Calf weaning weight differed by weaning age within calving system (P = 0.001), and calves from the Jun calving system that were weaned at 190 d of age tended (P = 0.06) to be lighter than calves of the same age from the Feb or Apr calving systems. Cow BW change and BCS dynamics were affected by calving system, but the proportion of cows pregnant in the fall was not. Cows suckled until later dates gained less or lost more BW during the 50 d between the first and second weaning than dry cows during this period. The previous year's weaning assignment did not affect production in the following year. Estimated harvested feed inputs were less for the Jun cows than for the Feb and Apr cows. We conclude that season of calving and weaning age affect outputs from rangeland-based beef cattle operations.     

Vitamin E status of healthy Swedish cattle

Using high pressure liquid chromatography the serum concentration of vitamin E was measured in dairy cows fed either hay or silage as their main roughage, in calves fed milk-replacer, and in young intensively fed bulls. The concentrates fed to the cows, calves and bulls were supplemented with 5–10, 25 and 5–10 mg DL-α-tocopheryl acetate per kg, respectively, and the milk-replacer for the calves was supplemented with 50 mg DL-α-tooopheryl acetate per kg powder. Cows fed silage as their main roughage had higher serum vitamin E concentrations (: 3.8–5.2 mg/l) than cows fed only hay (: 2.5–4.1 mg/1). Lactating cows had higher vitamin E concentrations than dry cows (: 4.1–5.2 and 2.5–3.8 mg/l, respectively) and calves and bulls had much lower vitamin E concentrations (: 1.4 and 1.2 mg/l, respectively) than cows. Thirty per cent of the calves and 41 % of the bulls had serum vitamin E concentrations less than 1.0 mg/l, suggesting that in these animals the conventional level of supplementation of feeds with DL-α-tocopheryl acetate in Sweden is probably inadequate for the prevention of nutritional muscular degeneration and other negative effects.     

Effects of calcium intake and parity on plasma minerals and bone turnover around parturition

Eight pregnant heifers (primiparous cows) and seven pregnant cows in their second, third and forth pregnancies (multiparous cows) were assigned to two groups and fed either a low calcium (Ca) diet (Ca, 0.46%) or a high Ca diet (Ca, 0.86%) ad libitum from 3 weeks before the expected calving date to 3 days after parturition. All cows were examined for a change in dry matter intake (DMI), plasma minerals and bone turnover around parturition. The dietary Ca level did not affect the DMI in both primiparous and multiparous cows. The DMI of primiparous cows was significantly lower than that of multiparous cows (P < 0.05) in both the low and high dietary Ca groups. The dietary Ca level did not affect the concentrations of plasma Ca, phosphorus, magnesium and parathyroid hormone throughout the experimental period. Plasma phosphorus in primiparous cows was significantly higher (P < 0.05) than that of multiparous cows around parturition. Plasma Ca and magnesium tended to be higher (P < 0.10) in primiparous cows. The dietary Ca level did not affect the plasma osteocalcin (OC) level measured as bone formation or the urinary deoxypyridinoline (DPD) excretion measured as bone resorption before parturition in both primiparous and multiparous cows. After parturition, the plasma OC level was lower than it was before parturition in multiparous cows fed a low Ca diet, and in primiparous cows. There were no significant differences in urinary DPD excretion between each group before and after parturition. Both the plasma OC level and urinary DPD excretion of primiparous cows were significantly higher than those of multiparous cows in both the low and high dietary Ca groups.     

Congenital joint laxity and dwarfism: A feed-associated congenital anomaly of beef calves in Canada

Five feeding trials were performed on three ranches to determine if a distinctive, recurring, congenital anomaly in beef calves was associated with feeding clover or grass silage without supplementation to pregnant cows overwinter. The anomaly, termed congenital joint laxity and dwarfism, was characterized at birth by generalized joint laxity, disproportionate dwarfism, and occasionally, superior brachygnathia. The anomaly had been documented for several consecutive years on these ranches and affected 2-46% of the calf crop.

Pregnant cows were divided randomly into feeding groups, and the number of abnormal calves in each group was tabulated. Supplementation of the overwinter grass/clover silage diet with hay (2.5-4.5 kg/head/day) and rolled barley (0.75-1.5 kg/head/day) eliminated the problem. Supplementation of grain, without hay, was not as effective. Varying the proportions of grass and clover in the silage, and the age of the silage, did not alter the teratogenic potency of silage. Vitamin D₃ supplementation did not reduce the risk of the condition. The definitive cause of congenital joint laxity and dwarfism was not determined.

     

Growth of mashona cattle on range in Zimbabwe. I. Environmental influences on liveweight and weight gain

Data from 1,456 purebred Mashona calves were analysed to determine environmental influences on growth rate and liveweight at birth, weaning (205 days) and 18 months of age. Calves were born between mid-September and mid-December each year. Year of birth was highly significant for all traits (P less than 0.001). Pre-weaning liveweight and weight gain increased as age of dam increased to seven years after which growth tended to decline. Post-weaning compensatory growth was apparent in calves of young dams. Male calves grew faster and were heavier at all stages than female calves (P less than 0.001). Calves from previously non-lactating cows grew more rapidly and were heavier at all ages than those from previously lactating cows. Birth weight increased as calving season advanced and calves born late maintained their growth advantage until 18 months of age. The results indicate that environmental influences experienced in early life persist long after weaning.     

The effect of clover silage treated with acrylic acid on selected indicators of metabolism in cows around the time of parturition and the status of their calves]

A trial was conducted with 16 cows divided into control and test group (eight cows in either); since day 57.6 +/- 21.1 before parturition, test cows were given feed rations for 107 days which contained 16.0 kg clover-grass silage a day, treated with 3 l acrylic acid per t ensiled matter. Control group of cows was administered feed rations containing silage treated with 4 l formic acid per 1 t ensiled matter from day 55.5 +/- 21.9. In the blood (plasma) of test cows the alkaline phosphatase activity was increasing gradually, in the time after parturition a tendency of lower glucose (P 0.05 to 0.01), thyroxine and triiodothyronine concentrations was observed, and the phagocytal activity of leucocytes and its index decreased. The levels of ketone bodies and aspartate aminotransferase activity were found to be higher. In this period in urine the pH value and net acid-base output were lower, while the inorganic phosphorus concentration was higher. No difference were observed in colostrum density, liveweight of born calves and in the target metabolic parameters in the blood (plasma) of calves. In the 30-day period of investigation the cows of test group gave an average daily milk yield lower by 1.5 l (in comparison with control cows). The residues of acrylic acid (method sensitivity of 1.0 mg acrylic acid in 1 l sample) were not detected in their colostrum and milk.     

Postpartum supplemental fat, but not maternal body condition score at parturition, affects plasma and adipose tissue fatty acid profiles of suckling beef calves

Three-year-old Angus x Gelbvieh beef cows, which were nutritionally managed to achieve a BCS of 4 +/- 0.07 (479 +/- 36 kg of BW) or 6 +/- 0.07 (580 +/- 53 kg of BW) at parturition, were used in a 2-yr experiment (n = 36/yr) to determine the effects of maternal BCS at parturition and postpartum lipid supplementation on fatty acid profile of suckling calf plasma and adipose tissue. Beginning 3 d postpartum, cows within each BCS were assigned randomly to 1 of 3 treatments in which cows were all fed hay and either a low-fat (control) supplement or supplements with either high-linoleate cracked safflower seeds (linoleate) or high-oleate cracked safflower seeds (oleate) until d 61 of lactation. Diets were formulated to be isonitrogenous and isocaloric, and safflower seed supplements were provided to achieve 5% of DMI as fat. Total concentration of fatty acids in plasma did not differ (P = 0.48) due to maternal BCS at parturition. Percentage of 20:5n-3 in plasma tended (P = 0.06) to be greater for calves suckling cows with a BCS of 6 at parturition. No other differences (P = 0.12 to 0.99) were noted in calf plasma fatty acid profile due to maternal BCS at parturition. Likewise, no differences were detected for total fatty acid concentration (P = 0.88) in calf adipose tissue due to maternal BCS at parturition. Weight percentage of 14:1 (P = 0.001) was greatest in adipose tissue of calves suckling cows fed control and oleate; however, the percentages of 14:0, 15:0, 16:0, 16:1, 17:0, and 18:3n-3 were greater (P < 0.001) in adipose tissue from calves suckling cows fed control compared with calves suckling cows fed linoleate or oleate. Percentages of 18:0, 18:1trans-11, 18:2n-6, and cis-9, trans-11 CLA were greater (P < 0.001) in adipose tissue from calves suckling cows fed linoleate compared with calves suckling cows fed control and oleate. Calves suckling cows fed oleate had greater (P < 0.001) percentages of 18:1trans-9, 18:1trans-10, and 18:1cis-9 in adipose tissue than calves suckling cows fed control or linoleate. Calf plasma and adipose tissue fatty acid profiles were reflective of milk fatty acids. Because fatty acids play an important role in metabolic regulatory functions, changes in milk fatty acid profile should be considered when beef cows are fed lipid supplements.     

Changes in the feed intake, pH and osmolality of rumen fluid, and the position of the abomasum of eight dairy cows during a diet-induced left displacement of the abomasum

During the last six weeks of the dry period, eight Holstein-Friesian cows were fed a restricted amount of grass silage; after calving, a mixture of maize silage and concentrates was offered in a feeding regimen designed to induce a displacement of the abomasum. In the first month after calving, the cows were monitored for the following variables: feed intake and composition, milk production, the position of the abomasum, and the pH and osmolality of the rumen contents. In five of the eight cows, a left displacement of the abomasum occurred between four and 21 days after calving in the absence of other diseases. The displacement was temporary, lasting between five and 36 consecutive hours and one or two days in two of the cows (floaters), and for three or more days in the other three. Before these three cows developed the displacement, their abomasum was 4.3 to 7.9 cm higher, its contents had a higher mean osmolality (+19.2 mosmol/kg), and the ratio of roughage to concentrates in their feed was lower (-0.87) than in the three cows that did not develop clinical signs of a displaced abomasum. There were no significant differences in these variables between the floaters and the healthy cows.     

Subsequent reproduction and calf performance of nonpregnant cows compared with pregnant cows and replacement females

This study was conducted with Angus, Polled Hereford and Santa Gertrudis straightbred and crossbred cows. The subsequent cow breeding and calf performance of cows that were nonpregnant (NP) were compared with cows that were pregnant (PG) at the time calves were weaned. All NP cows had a calf the year previous to their being nonpregnant. They were diagnosed as physically sound with no detection (by rectal palpation) of an abnormal reproductive tract. The NP and PG cows were aged 4 to 9 yr. Also, the NP cows were compared with replacement females exposed to calve first as 2- and 3-yr-olds (H2 and H3, respectively), and with cows exposed for second calving as 3-yr-olds (C2). Cows were assigned within breed composition and age to sire breeding groups on pasture. Subsequent calving and weaning rates were similar for NP, PG and H2 cows, similar for H3 and H2 cows and lowest (P less than .05) for C2 cows. Calves from NP and H3 cows were born earlier (P less than .05) in the calving period than calves from PG and H2 cows, whereas calves from C2 cows were born later (P less than .05) than those from NP, PG and H3 cows. Calving difficulty was similar for NP, PG and C2 and greatest (P less than .05) for H2 cows. Calf 205-d weights were highest (P less than .05) for NP, similar for PG and H3 and lowest (P less than .05) for C2 and H2 cows. Calf weaning weight per cow exposed for breeding from NP cows was 13.8, 32.3, 55.2 and 1.0 kg higher than from PG, H2, C2 and H3 cows, respectively. Causes for cows being nonpregnant were reported. Also, calving patterns during 6 consecutive calving periods (6 yr) were evaluated.