Weaning Group Research Articles

The effect of weaning age on foal growth and radiographic bone density

SUMMARY Seven foals weaned at 4.5 months were compared to eight foals weaned at 6.0 months at three-week intervals before and after weaning to assess the effect of weaning and weaning age on growth and bone density. Average daily gain (ADG) declined (P < .01) in the first week after weaning in both weaning groups, and remained lower (P < .05) than preweaning gain in foals weaned at 6.0 months at three weeks' postweaning. Cannon circumference (CC) growth was depressed at three weeks (P < .05) and six weeks (P <. I0) postweaning when foals were weaned at 4.5 months, but not when foals were weaned at 6.0 months. Withers height (WH) and radiographic bone density were not affected by weaning or weaning age. By 203 days of age, there were no differences in body weight, CC, WH or bone density between weaning groups. Therefore, weaning foals at 6.0 months of age seems to provide little growth advantage over weaning foals at 4.5 months of age. Radiographic analysis across treatments revealed that the medial density of the left third metacarpal (MCIII) was greater (P < .01) than the right MCIII, thereby suggesting that both forelimbs should be included when assessing dietary or exercise effects on radiographic bone density.

Endocrine Responses to Weaning and Changes in Post-Weaning Diet in the Young Pig

The effects of weaning and changing post-weaning diet composition on growth patterns and growth-related hormonal profiles were evaluated in neonatal pigs. Forty-eight crossbred piglets were assigned to two groups ( n = 24/group) based on weaning at 2 or 3 wk of age (2W and 3W groups, respectively). At weaning, piglets were removed from the sow and placed on a commercial starter ration for the first 11 d post-weaning (Phase I diet). At Day 12 post-weaning, pigs were placed on a growing ration for the remainder of the study (Phase II diet). Body weights and blood samples were collected twice weekly from birth until 42 d of age. Serum insulin-like growth factor (IGF)-1, IGF-2, and average daily gain (ADG) were reduced (P < 0.05) in both groups as a result of weaning, whereas serum growth hormone (GH) was elevated (P < 0.05). Earlier weaning resulted in a greater reduction in growth rate and serum IGF-2 values (P < 0.05). Mild reductions in ADG occurred after the Phase I to II dietary change in both weaning groups (P < 0.05), but serum IGF-1 decreased only in the 2W group (P < 0.05). Growth hormone concentrations tended to increase after the change in post-weaning diets (P = 0.07 and 0.16 in 2W and 3W, respectively). Serum thyroxine (T 4) and triiodothyronine (T 3) levels were unaltered by weaning but declined in both groups after the change in starter diets (P < 0.05). Changes in cortisol concentrations were not associated with weaning or the change in post-weaning diets. With the exception of serum IGF-1 concentrations, which were elevated in the 2W group, growth and endocrine endpoints were equivalent between experimental groups at the end of the study (42 d of age). These results indicate that earlier weaning and changing solid diets can more severely affect patterns of early growth and related hormone secretion, but effective compensatory mechanisms restore normal physiological and physical development.

Factors associated with very early weaning among primiparas intending to breastfeed.

The major objective of this study was to identify predictor variables that accurately differentiated breastfeeding women who weaned during the first 4 weeks, those who weaned between 5 and 26 weeks, and those who weaned after 26 weeks. Predictors were demographic variables, Theory of Planned Behavior (TPB) variables, breastfeeding knowledge, and difficulties experienced during the first month. Primiparas who delivered healthy infants in an urban midwestern hospital provided initial data prior to discharge. Follow-up occurred at 1, 3, 6, 9, and 12 months. Following appropriate bivariate analyses, polychotomous logistic regression was used to determine predictors of weaning group. Linear multiple regression was used to predict intended duration. Most of the 84 women who weaned very early had intended to breastfeed considerably longer. According to the multivariate analysis, women who weaned earlier were younger, had completed fewer years of education, had a more positive bottle-feeding attitude and a less positive breastfeeding attitude, intended to breastfeed less time, had lower knowledge scores, had higher perceived insufficient milk scores, and planned to work outside the home. Variables postulated by the TPB to be direct predictors of intention explained 36% of the variance in intended duration. Women at risk for early weaning can be identified with reasonable accuracy using a TPB-based conceptual framework expanded to include breastfeeding specific variables. Casefinding using empirically derived screening methods and careful postpartum follow-up, along with professional intervention, should be used to avert unintended early weaning.

Successful magnesium sulfate tocolysis: Is “weaning” the drug necessary?

OBJECTIVE: Magnesium sulfate is the most commonly used tocolytic agent for preterm labor. A common clinical practice is to slowly discontinue the drug (wean) after successful tocolysis. Our objective was to determine the necessity of this practice. STUDY DESIGN: A prospective, randomized clinical trial was performed from June 1993 to July 1996. After successful magnesium sulfate tocolysis, patients with preterm labor were randomized to two groups: stopping the drug abruptly (no weaning) or gradually weaning the drug (approximately 1 gm every 4 hours). Preterm labor was defined as documented cervical change with regular uterine contractions or regular uterine contractions with a cervix of 2 cm and 75% effacement. The primary outcome variable was the necessity to reinstitute magnesium sulfate therapy within 24 hours of discontinuation of successful tocolysis. RESULTS: One hundred forty-one patients completed the study. No patient in the no-wean group required retocolysis within 24 hours of magnesium discontinuation. However, eight patients in the wean group required retocolysis within 24 hours of magnesium discontinuation ( p = 0.01). Significantly more patients in the wean group had retocolysis during pregnancy (3 vs 12, p = 0.03). Patients in the wean group were also in the labor and delivery unit longer and, as would be anticipated, received magnesium sulfate significantly longer. No differences in the neonatal outcomes were noted between the two groups. Seventy-seven percent of the patients in the study were delivered prematurely. CONCLUSION: This study demonstrated an increased need for retocolysis in the group weaned from magnesium sulfate. We also found that patients in the wean group had an increased labor and delivery time and a longer administration time of magnesium sulfate. Thus weaning magnesium sulfate increases health care cost. The practice of weaning magnesium sulfate does not appear beneficial. (Am J Obstet Gynecol 1997;177:742-5.)

Microbial contamination of weaning foods.

A survey was conducted to determine the prevalence rate of Escherichia coli in different foods being fed to children in the weaning age group. The samples were collected from middle income group (MIG) and high income group (HIG) houses in different localities in Chandigarh. A total of 530 MIG and 525 HIG houses were selected on the basis of availability of children in the weaning age group. A total of 2,016 samples of weaning foods were collected. Isolation of Escherichia coli from MIG and HIG houses was 66.75% and 8.5% respectively. Enterotoxigenic Escherichia coli were detected in 61.47% and 43.5% of the total Escherichia coli isolates from MIG and HIG houses respectively. 'O' serogrouping of the isolates was done and the predominant serotypes found were 06, 0106, 043, 057, 01. The laboratory studies showed that almost all weaning food samples prepared in the laboratory supported the growth of known enterotoxigenic Escherichia coli.

The repeated procedure of weaning and peer group formation causes accumulation of stress and changes of plasma cortisol level and natural killer activity in squirrel monkeys (Saimiri sciureus)

The psychological stress was evaluated in repeated and unrepeated procedures of weaning as well as forming peer group in squirrel monkeys. The repeated procedure included the process of increasing the period of separation or formation stepwise during four weeks. The plasma cortisol levels and natural killer (NK) activities were monitored during experiment to evaluate the stress in infant monkeys. The plasma cortisol level rapidly increased two to three times as much as basal level and kept high levels throughout experiment in repeated group. In the infants of unrepeated group, significant increase of cortisol level and decrease of NK activity were observed in day-1, but both of them returned to the basal level at day-7. Both cortisol level and NK activity did not show any change with exception of decrease in NK activity at day-7 in infants who were introduced into peer group without repeated procedure. On the other hand, both cortisol level and NK activity increased during the repeated procedure. These results indicate that both weaning and forming peer group induce the psychological stress in infant squirrel monkeys, resulting in changes of plasma cortisol level and NK activity. Repeating the procedure of separation or introduction applied in this study caused the accumulation of stress. Although plasma cortisol level increased in infants exposed to both weaning and forming peer group, the changing pattern of NK activity differed between them. This finding suggests that social or psychological stress show two different effects on immune function, suppression, and enhancement depending on the level of stress.

New Predictors for the Weaning from Mechanical Ventilation

New indicators, Oxygen Cost of Breathing (ΔVO2), Work of Breathing (WOBp), intrapreural Pressure Time Product (PTP) and P0.1 were clinically examined to determine which of these indicators is the most specific and sensitive for predicting the outcome of weaning from mechanical ventilation. Twenty-three weanings were attempted and divided into a successful weaning group (Group-S) and a failed weaning group (Group-F). There were significant differences in Minute Volume, ΔVO2, ΔVCO2, WOBp, P0.1, PTP, Lung Compliance and Intrinsic PEEP between the groups. ΔVO2 and P0.1 in particular, were statsitically significantly different in the two groups (ΔVO2: 14.4±11.7 in Group-F VS. -7.7±9.6% in Group-S P<0.005, P0.1: 4.9±1.6 in Group-F VS. 2.5±1.3cmH2O in Group-S P<0.01) and 5% in ΔVO2 and 3.5cmH2O in P0.1 are the Cutt-Off values for prediction of the success or failure of weaning trials. WOBp greater than 9 Joule min-1 and PTP above 200cmH2O sec min-1 suggested difficulty in weaning from the ventilator. ΔVO2 and P0.1 are considered to be the most sensitive indicators, because in the group-F these indicators exhibited significant increases in the early stage of weaning from the ventilator.

Changes in pituitary, hypothalamic and brain progestin-metabolizing enzyme activities during lactation

Progesterone 5α-reductase activity and 5α-dihydroprogesterone 3α-hydroxysteroid oxidoreductase (3α-HSOR) activities (NADH- and NADPH-linked) were measured in anterior pituitaries, hypothalami and brains from lactating rats (8 and 21 days postpartum) and non-lactating (60-day-old cycling) rats. Tissue levels of these three enyme activities varied significantly among the three groups examined. In terms of pituitary, mean levels of both of its 3α-HSOR activities were 40–140% higher in actively lactating rats (8 days postpartum) relative to mean levels in lactating rats at weaning (21 days postpartum) or in non-lactating rats. There were no differences in pituitary progesterone 5α-reductase activity among the three experimental groups. In the hypothalamus, the NADPH-linked 3α-HSOR was elevated (50%) at 8 days of lactation compared to the group at 21 days. Hypothalamic NADH-linked 3α-HSOR levels did not vary among the 3 groups. Hypothalamic progesterone 5α-reductase levels in the actively lactating and weaning groups were 30% lower than those of the non-lactating group. Brain levels of progesterone 5α-reductase were also lower these two lactating groups (35–55%) as compared to the non-lactating control group. In brain, NADPH 3α-HSOR activity did not vary among the three groups, but levels of NADH 3α-HSOR activity were lower (40–50%) in the weaning group as compared to the actively lactating and control groups. These findings suggest the possibility that tissue changes in these progesterone-metabolizing enzyme activities during lactation and at weaning are influencing the in situ supply of 3α,5α-tetrahydroprogesterone and 5α-dihydroprogesterone and their derivative effects on GABA A receptor activity and prolactin and gonadotropin release. The decreased activity of progesterone 5α-reductase in hypothalamus and brain would presumably reduce in situ 5α-dihydroprogesterone formation while increases in 3α-HSOR activity would suggest higher in situ 3α,5α-tetrahydroprogesterone formation especially in the pituitary.

Cohort study of natural transmission and two methods for control of caprine arthritis-encephalitis virus infection in goats on a California dairy

Summary A prospective observational cohort study of 361 dairy goat kids was conducted to compare 2 methods of controlling caprine arthritis-encephalitis virus infection under commercial dairy conditions. To compare effectiveness of feeding kids pasteurized milk vs serologic testing and segregation in addition to pasteurized milk feeding, goats were monitored up to the age of 30 months by use of monthly agar gel immunodiffusion testing. Survival analysis methods were used to determine whether age at seroconversion differed between the 2 groups. Significantly lower rates of seroconversion were observed in the segregated group (P &lt; 0,001), compared with the nonsegregated group. Of 193 goats in the pasteurized milk-only group, 146 (75.6%) seroconverted within the 30-month study period, whereas infection was detected in 39 (23.2%) of 168 goats in the test/segregated group. Nonsegregated goats were 3.37 times more likely to seroconvert by 24 months of age, and 70.3% of seroconversions by 24 months of age could be attributed to nonsegregation. For age-specific intervals beyond 180 days of age, 70 to 100% of seroconversions could be attributed to lack of segregation. Cohort life tables for age at seroconversion were reported for each group. Type of colostrum fed, sex, and weaning group (season) were not significantly associated with age at seroconversion. Saanen goats had lower age-specific risk of seroconversion in the nonsegregated group alone and overall. Non-Saanen goats were 1,5 times more likely to seroconvert than were Saanen goats, when adjusted for a possible confounding effect of weaning group. Results indicate that pasteurized milk feeding and routine test and segregation would be a substantially more effective means of control of the disease in dairy goat herds than would pasteurized milk feeding alone.

Effect of pig weaning weight and associated nursery feeding programs on subsequent performance to 105 kilograms body weight.

An experiment using a total of 210 crossbred pigs from two farrowing groups evaluated the effects of three weaning weights and their associative starter feeding program on subsequent postweaning performance to 105 kg BW. One group of pigs nursed their dams in outside heated hutches (Trial 1), and a second group was raised in a centrally heated farrowing house (Trial II). The three pig weaning weight groups ranged in weight from 1) 4.1 to 5.0 kg, 2) 5.5 to 6.8 kg, and 3) 7.3 to 8.6 kg. Pigs in Group 1 were fed a high nutrient dense diet (HNDD) for a 2-wk period followed by a corn-soybean meal-dried whey (C-SBM-DW) and then a corn-soybean meal (C-SBM) diet, each for a 2-wk period. Group 2 was fed the same diet sequence except that HNDD was provided for 1 wk, whereas Group 3 was provided only the C-SBM-DW and the C-SBM diets each for 2 wk, consecutively. At the end of the nursery period, pigs were fed C-SBM diet formulations to 105 kg BW. Pigs of Trial I averaged 5.2 d older at weaning than those raised in the central farrowing house, but only a 1.5-d difference existed between light- and heavy-weight groups in both trials. Gains and feed intakes for the three weaning groups were higher as weaning weight increased during both the nursery and the growing-finishing period. There did not seem to be a compensatory growth response for lighter-weight weanling pigs even though they had been fed starter diets containing milk products. Consequently, fewer days (approximately 15) were required for the heavier-weight weanling pig group to reach a final weight of 105 kg than for the light-weight group. The medium-weight group required an intermediate number of days to reach 105 kg.

Effects of altered dietary sodium intake on hormonal profiles in salt-sensitive hypertensive rats

Blood pressure and selected putatively influential hormones were measured in Brattleboro rats which were without diabetes insipidus and which were subjected to various manipulations in dietary sodium intake. Rats fed a control diet from weaning to 16 weeks of age showed a slow increase in blood pressure whereas rats fed a sodium-enriched diet for the same period exhibited sustained hypertension (115 +/- 3 versus 169 +/- 5 (S.E.M.) mmHg). In animals fed a sodium-enriched diet plasma concentrations of antidiuretic hormone (ADH) were significantly increased from 55 +/- 8 to 108 +/- 5 fmol/l. Rats fed the control diet from weaning (group A) and subsequently maintained on that diet or changed to a sodium-enriched diet or sodium-deficient diet showed no differences in their blood pressure. Plasma hormone concentrations were similar in these groups, with the exception of aldosterone suppression in rats switched from control to a sodium-enriched diet (0.26 +/- 0.04 versus 0.08 +/- 0.03 nmol/l; P less than 0.001). Animals fed the sodium-enriched diet from weaning to 16 weeks of age (group b) and either maintained on that diet or changed to a control diet showed little change in their established hypertension. Transfer to the control diet was associated with increased plasma renin concentrations (PRC) (13.8 +/- 2.1 to 122.6 +/- 6.2 nmol/l) and plasma aldosterone concentrations (0.04 +/- 0.01 to 0.08 +/- 0.01 nmol/l; P less than 0.001) but corticosteroids and ADH concentrations were unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of Decoquinate Fed to Neonatal Dairy Calves on Early and Conventional Weaning Systems

Forty-four Holstein calves were assigned randomly to treatments in a 2 × 2 factorial arrangement of weaning age (4 or 7 wk) and coccidiostat (treatment or control). The objective of this study was to compare the effectiveness of a coccidiostat, decoquinate, on health parameters and growth of neonatal dairy calves on early and conventional weaning systems. Calves weaned at 4 wk had greater intakes of grain in wk 5 to 7 than did calves weaned at 7 wk. Differences in intakes between weaning groups were not apparent from wk 8 to 24. Fecal coccidia oocyst counts were not affected by age at weaning but were affected by coccidiostat feeding at the rate of .5 mg/kg BW/d offered from 3 d of age and throughout the trial. No effects due to age at weaning or coccidiostat treatment were found in plasma glucose, urea N, and minerals (Ca, P, Na, Cl, K, Mg). Growth parameters were significantly increased in treated animals. Total BW was increased (wk 9 to 24) in treated over control calves (127.3 versus 118.5kg). Height at withers was also increased in treated calves (95.0 vs. 92.8cm). Coccidiosis treatment increased growth of dairy calves from 9 to 24 wk, but no interactions were found between coccidiosis treatment and age at weaning.

The effectiveness of 48-hour calf removal, Syncro-Mate-B or prostaglandin treatments in advancing the breeding season of beef cows

A 3-yr study was conducted to evaluate different methods of inducing beef cows to cycle and successfully breed earlier in the breeding season. Three hundred beef cows nursing their calves were allocated to groups to be treated with Estrumate or Syncro-Mate-B or to serve as untreated controls. Half of the calves in each group were weaned for 48 h prior to the start of the breeding season. The 48-h weaning group had a significantly higher proportion of animals with calving intervals of less than 365 d (P < 0.05), and cows in this group tended to have more calves born in the first 21 d of the next calving season. There was no benefit in using any of the hormonal treatments. Forty-eight h calf removal resulted in a 5% (P < 0.01) reduction in calf weight gain to final fall weaning, regardless of hormonal treatment.

EFFECTS OF DATE OF WEANING ON SUBSEQUENT PERFORMANCE OF BEEF COWS AND THEIR FEMALE CALVES

1233 April/May born calves were weaned either on 30 Sept. (EW) or 31 Oct. (LW) to assess the effects of weaning date on subsequent performance of their dams and female calves. Cows in the EW group lost less weight than those in the LW group in the month of October (0.003 vs. 0.48 kg d−1, P &lt; 0.05). Dam's breed group, year and the interaction between year and age of dam also had significant effects on weight change during October. Cows generally lost weight between weaning and the next calving and the two weaning groups were similar in body weight at calving and reproductive performance. The reproductive performance of the EW and LW female calves were also quite similar. It can be concluded that weaning April/May born calves in September rather than October would not influence the subsequent production of the dams or their female calves, but would probably reduce their maintenance requirements as they enter the cold season in better condition. Key words: Weaning date, beef cows, reproduction, weight changes

Plasma concentrations of insulin-like growth factor-I and insulin in the infant calf: ontogeny and influence of altered nutrition.

The developmental pattern of plasma insulin-like growth factor-I (IGF-I) and insulin in calves subject to different patterns of weaning was investigated from birth until the age of 6 months. Fifteen male Friesian calves were fed on whole milk (10% of body weight per day) for the first 8 weeks after birth, then allocated into three balanced groups. Group 1 was weaned at 8 weeks; group 2 was weaned at 8 weeks, returned to milk-feeding at 13 weeks to be weaned again at the age of 16 weeks; group 3 was weaned at 12 weeks. After weaning the calves were fed on concentrates and lucerne hay. At birth, circulating concentrations of IGF-I correlated with birth weight (r = 0.78, P less than 0.001). There was a significant (P less than 0.001) fall in plasma IGF-I from birth (40.3 +/- 2.5 micrograms/l) until 5 weeks (23.8 +/- 1.3 micrograms/l), and then a gradual (P less than 0.01) rise until week 8 (35.0 +/- 2.2 micrograms/l). Weaning (groups 1 and 2 after week 8) caused a significant (P less than 0.01) decrease in plasma IGF-I (20.5 +/- 1.9 micrograms/l); thereafter plasma levels of IGF-I rose gradually (P less than 0.01) in animals fed on concentrates. The milk-fed calves (group 3) showed a progressive increase in plasma IGF-I with age until they were weaned at 12 weeks (51.0 +/- 3.4 micrograms/l); IGF-I levels then decreased to be similar to group 1 (32.5 +/- 2.1 micrograms/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of weaning weight, co-mingling, group size and room temperature on pig performance.

Four experiments involving 3- to 4-wk-old, ad libitum-fed weanling pigs (n = 809) were conducted to determine the effects of initial pig weight, co-mingling of litters, numbers of pigs/pen and room temperature on pig performance in a conventionally equipped nursery. Pigs that were largest at birth were largest (P less than .01) at weaning (r = .66) and also at 28 d postweaning (r = .62). Light-weight pigs (3.8 kg) at weaning gained more slowly (P less than .05) for 4 wk postweaning than heavy weight pigs (6.5 kg). Growth curves for the light and heavy groups of pigs remained parallel throughout the 4-wk nursery period, indicating that small pigs were not making compensatory gains. Growth rates of average-weight pigs (5.2 kg) were intermediate to and not different (P greater than .05) from light- and heavy-weight pigs. Penning 8, 16 or 24 pigs together while maintaining constant flooring area and feeder and waterer space/pig did not reduce (P greater than .05) intakes, gains or feed:gain ratios. Co-mingled litters grew comparably (P greater than .05) to pigs reared as littermates. In temperature studies, pigs were reared either in a room maintained at 29 +/- 2.8 C throughout the 28-d trials or at 29 +/- 2.8 C the first week postweaning and 24 +/- 2.8 C thereafter. Reducing the nursery temperature to 24 +/- 2.8 C after 1 wk depressed (P less than .05) intakes, gains and feed efficiencies as compared with the warmer temperature regimen.

THE EFFECTS OF WEANING SCHEDULE, DURATION OF MILK FEEDING AND FISHMEAL ON CALF PERFORMANCE

Two experiments were conducted to measure the effects of weaning procedure and duration of milk feeding on calf performance and overall milk consumption. In exp. 1, compared with calves weaned when consuming 500 g d−1 of starter (control), those weaned when intake reached 1000 gd−1 (delayed) consumed 2.5 times as much milk and those fed gradually diminishing milk levels until weaned at 1500 g d−1 of starter intake (gradual) consumed about 1.5 times as much milk. Both the control and delayed groups experienced a growth setback of up to 8 d at weaning. There was no change in growth rate for the gradual weaning group. In exp. 2, the calves were gradually weaned over 7 d commencing at 28 d of age and were fed either supplemental milk, wet fishmeal, dry fishmeal or no protein supplement (control) for an additional 140 d. Calves fed milk grew fastest and had the best feed:gain ratio (P &lt; 0.01). Those fed fishmeal grew faster than the controls and had better feed:gain ratios (P &lt; 0.01). There was no difference between the wet and dry fishmeal suggesting that any increased rumen by-pass through the esophageal groove reflex did not result in improved animal gain. The potential value to the producer of feeding over quota milk to calves marketed at 168 d was calculated to be $15.22 hL−1 on the basis of dry feed replaced and increased weight gain by the milk-fed calves. Key words: Calves, milk, weaning, by-pass protein, fishmeal

Early weaning predisposes rats to exacerbated activity-stress ulcer formation

Rats were weaned early (Day 15), normally (Day 21) or late (Day 27). When they reached 200 g (±10) they were placed into the activity-stress paradigm. Half the rats in each weaning group were housed in activity-wheel cages and fed only 1 hr each day. The remaining rats served as food-yoked home cage controls and were fed only that amount of food eaten by their wheel-housed partners. Early weaned rats ran more than normally or late weaned animals. Early weaned rats also died at a faster rate and exhibited a significantly greater cumulative ulcer length than did normally or late weaned rats, although ulcer incidence did not differ between the groups. No ulcers occurred in home cage control rats. Early maternal deprivation may generally predispose rats to stress-induced gastrointestinal disease, whether or not such disease has an acid etiology.

Poids et métabolisme des réserves lipidiques au cours de la croissance du chevreau

Adipose tissue growth was studied in two experiments. In the first one, 36 Alpine male kids fed with milk replacer only were slaughtered at 8, 14 or 20 kg (groups A, B and C, respectively). Perirenal adipose tissue developed earlier than omental adipose tissue, but from about 30 days of age, the latter was heavier (allometric coefficients: 2.18 and 1.36 for omental and perirenal adipose tissues, respectively). Even in group C animals, subcutaneous adipose tissue was scarce. When expressed in grams of wet tissue, the lipoprotein lipase (LPL) activity of omental adipose tissue decreased with age. This decline was more marked between groups B and C than between groups A and B (37 and 14%, respectively). Total LPL activity of omental tissue was 3-fold higher in group B than in group A and 3.7-fold higher in group C than in group A. This activity apparently had no relation with the amount of milk intake, daily mean weight gain or omental adipose tissue weight. In the second experiment, 18 male kids were slaughtered unweaned at 6 weeks or 2 or 14 days after weaning (groups A, B and C, respectively). After weaning, the weight of all adipose tissues decreased. Perirenal adipose tissue weight diminished earlier and more intensively than in the other adipose tissues (80% weight drop in 14 days). The weight loss of omental, pericardiac and mesenteric adipose tissue was 65, 49 and 15%, respectively. As with other lipogenic enzymes, the activity of LPL was highest in omental adipose tissue. In perirenal, pericardiac and mesenteric tissues LPL activity was 30, 45 and 60% less than omental activity. In sternal adipose tissue, LPL activity was very low. Acetyl CoA carboxylase (ACX) was active in the internal tissues of unweaned kids, but at a low level, i.e. about one-twentieth of that of LPL. Glucose-6-phosphate dehydrogenase (G6PDH) had a higher activity than NADP-malate dehydrogenase (EM). Soon after weaning, all of these enzyme activities dropped sharply. Two days after weaning, LPL activity declined by about 90% in all tissues, but 14 days after weaning it rose again, especially in perirenal adipose tissue. However, it reached a lower value than in unweaned kids. On the contrary, 14 days after weaning, group C ACX activity returned to a lower value than that of group B.

Analysis of some factors which affect the productivity of beef cows and of their calves in a marginal rainfall area of Rhodesia 3. Factors affecting calf birth weight, growth to 240 days and use of concentrates by cows and their calves

ABSTRACTThe birth weight and growth rate of sucking calves reared by three groups of cows grazing on veld and receiving different amounts of concentrates during winter and the first 8 weeks of lactation were studied over four successive calving seasons. Calves were weaned at either 150 or 240 days. The efficiency of use of concentrates for weaned calf production was calculated.Calves from cows given most concentrates were heavier (P&lt;0·01) than othei calves at birth, 150 days and 240 days. Milk consumption during the first 98 days of life accounted for most of the variation in pre-weaning growth. Time of weaning had little effect (P&lt;0·05) on birth weight of the next year's calf and although cows in the early- weaning groups produced calves which were the heaviest at 150 days (P&gt;0·05) these calves weighed less than other calves at 240 days (P&lt;0·001). Simple and multiple regression analyses were used to show that birth weight was affected significantly by cow-weight change during winter and these differences were in part independent of treatment and year. Calf birth weight increased as age of dam increased but this was due to increase in weight of cow with age. Within classes, calf birth weight had a significant and positive effect on weight gain after accounting for milk consumption and this was shown to be an effect of sex. Cows given concentrates produced more weight of 240-days-old weaned calf per year than those given none (P&lt;0·01), and late weaning led to the production of more weaned calf per annum than early weaning (P&lt; 0·001) even when allowance was made for differences in concentrate consumption.