Suckling Treatment Research Articles

Effects of prepartum melatonin treatment and suckling on postpartum reproductive performance of Beetal goats under subtropical conditions

The current study determines the effect of prepartum melatonin treatment on postpartum reproductive cyclicity, uterine involution, the onset of estrus, and ovarian activity in restricted or continuous suckled Beetal goats. Forty-six pregnant goats of 110 days gestation were either inserted with melatonin implants (M; n = 24) or left untreated (control, C; n = 22). Each group was subdivided into continuous (CS) and restricted suckling (RS) groups i.e., MCS (n = 11), CCS (n = 11), a ” ”MRS (n = 13), and CRS (n = 11) to monitor estrous response while uterine involution and ovarian activity were monitored in a subset of goats (n = 8 in each group) via transrectal ultrasonography (7.5 MHz transducer) twice a week. Blood BHBA and glucose levels were monitored 40 days before and 28 days after kidding. Data were analyzed using multifactor analysis of variance (ANOVA) designs, Chi-square, and Student’s t-test (SPSS version 20). Estrous response of goats was similar in MRS (30.8 %), CRS (45.4 %), and MCS (18.2 %) groups; however, MRS and CRS goats had better (P < 0.05) estrous response than those of CCS (0 %) goats. Between the groups, the ovulatory response and interval to 1st postpartum estrus were similar (P > 0.05). Melatonin tended to have shortened (P = 0.07) the interval to 1st postpartum ovulation and placental expulsion time (P < 0.05) in melatonin-treated than untreated goats. Melatonin or suckling treatment did not affect Gestation length, kidding time, uterine involution, and regression of caruncles (P > 0.05). BHBA levels were higher (P < 0.05) at 28 days postpartum than 40 days before kidding in all groups; however, glucose levels were similar in all groups except CCS. In conclusion, restricted suckling and prepartum melatonin treatment have more impact on postpartum reproductive performance than prepartum melatonin treatment alone in Beetal goats.

PSIII-2 Considering a large creep pellet as a means to improve suckling and early weaned pig performance

Abstract This study evaluated the benefit of creep feeding with large pellets (10mm diameter, Masterfeeds, London, ON, Canada) on pre- and post-weaning pig performance. Litters from two farrowing groups were assigned to one of 2 treatments: Control (no creep n= 25 litters) and Creep (large creep pellets n = 24) during the suckling phase. Pellets were provided beginning 7 d after the first sow farrowed within a group until weaning at 21 d. Pellets were placed in shallow plastic feeders three times/day (100-150 g at a time as needed) to ensure access to fresh feed. Creep pellets contained 2500 ppm zinc and ferric oxide-dyed biscuit crumbles were added at 5% inclusion in Phase 1 nursery diet. Therefore, fecal zinc concentration at 2 to 3d prior to weaning and red fecal coloration 2 to 4d after weaning were used to identify “eaters” from “non-eaters”. Pigs were weaned at 21 ± 2 d into pens based on suckling treatment. Data were analyzed as a randomized complete block with the sows as a random effect (PROC MIXED, SAS Inst., Inc., Cary, NC). Post-weaning fecal swabs data were analyzed by frequency test using the PROC FREQ procedure in SAS. There was no difference in pig weight prior to creep pellets. At weaning, Control pigs were heavier due to greater daily gain (P &amp;lt; 0.01; Table 1) than Creep pigs. However, there was no difference in d34 BW due to greater (P &amp;lt; 0.05) daily gain of Creep pigs in the post-weaning period. A greater proportion of Creep pigs were identified as “eaters” on d2 post-weaning (43 vs 33%, □ 2 = 0.004; Figure 1). Lighter weight at weaning in Creep pigs may be due to temporary distraction from suckling; however, exposure to large creep feed pellets pre-weaning improved pig feed intake and growth post-weaning.

The effect of permanent or temporary contact with the lamb and contact with males on the lambing to first ovulation interval in Saint Croix sheep

The effect of suckling and presence of the lamb, or ram, on the lambing to first ovulation interval in Saint Croix sheep was determined. Ten days after lambing 50 ewes and their lambs were assigned to three different suckling treatments: continuous suckling (CS), restricted suckling (RS), restricted lamb presence (RP). Ewes from each treatment were allocated to groups that had contact with a ram (TR) or remained isolated from rams (IR). Therefore, overall, there were six groups with 2 factors: CS-IR (n=7) CS-TR (n=7); RS-IR (n=11); RS-TR (n=11); RP-IR (n=7), and RP-TR (n=7). The presence of the ram (P=0.01) and restricted suckling (P=0.05) reduced the interval from lambing to first ovulation, while no interaction was found (P>0.05) between these two factors. An effect of treatment and its interaction influenced significantly the number of vocalizations and growth rate in lambs. At the day of weaning RP vocalized more than RS (P<0.01), which in turn vocalized more than CS (P<0.01), followed by a general decline to pre-weaning levels 48h later. Lambs in RP had greater growth rate during first 3 d after weaning compared with RS (P<0.05), which displayed greater growth rate that CS (P<0.05). In addition, an effect of treatment (P=0.05) was found in cortisol concentration. Our results indicate that Saint Croix ewes respond to the ram effect in early postpartum, shortening the resumption of postpartum ovarian activity. When this technique is combined with restricted suckling, additional benefits are achieved for lambs with reduced weaning stress.

FLUSHING, SUCKLING AND SEXUAL MATURITY OF SMALL RUMINANTS FED DIET CONTAINING SILAGE OF TRITICALE, BERSEEM OR ITS MIXTURE

objective of this study was to investigate the effect of three types of silage (triticale, berseem and their combination) supplemented to concentrate fed mixture (CFM) on productive, as suckling milk amount, growth rate of newborns and reproductive efficiency, as fertility rate and sexual development of male lambs to be used as sires. Two small ruminate breeds (ewes and does) were assigned into three treatment groups. Forty-two ewes (n=14 ewe in each treatment) and fifty-seven does (n=19 does in each treatment). All animals were received diets at 21 days pre-mating season (as flushing diet) up to weaning. The feeding treatments (T) offered as following: T1 contained 60% CFM + 40% triticale silage, T2 included 60% CFM + 40% admixture silage (50% triticale and 50% berseem) and T3 contained 60% CFM + 40% berseem silage. To determine suckling milk amount of maternal; twelve ewes (n=4 in each treatment) and eighteen does (n=6 in each treatment) symmetrical in reproductive and productive characteristics were used. The maternal in suckling treatment were received the same T1, T2 and T3 diets mentioned above. In respect of the newborn growth rate, all suckling lambs and kids from birth up to weaning were used. In sexual maturation evaluation, fifteen healthy Rahmani lambs with normal genitalia, aged 150 days and at initial body weigh (22.21±0.42 kg) were allocated into three treatments; five lambs / treatment. Results showed that ewes and does in T2 group had a higher reproductive performance, parity patterns and reproductive ability than those in other treatments (T1 and T3). The clearly differences wereobserved among the dietary treatments during suckling period of ewes and does. The maternal fed on T2 produced more (P<0.05) amounts in suckling milk than those maternal fed T1 and T3. Consequently, T2 improved (P<0.05) newborns growth rate compared to newborns in either T1 or T3 groups. Furthermore, T2 group achieved better (P<0.05) sexual developments (i.e., age at puberty, body weight, scrotal circumference, testicular diameter, testicular length, testicular volume and semen characteristics at puberty) than T1 and T3 groups. These findings indicate that the inclusion of admixture silage has no adverse effects on productive and reproductive performance, suckling milk production and growth rate of newborns. Admixture silage causes earlier sexual maturation and goodness semen parameters of Rahmani male lambs. Thus, mixing more than types of silage may be a promising strategy nutrition in the future.

Nursing Reduction Strategies to Enhance Estrus in Lactating Sows and Effects on Performance of Pigs to Market Weight

A total of 135 sows (PIC 1050), ranging from parity 1 to 5 (2.6 ± 1.4), were used in 5 consecutive farrowing groups (February to August). The objectives were to evaluate different suckling reduction strategies for inducing lactational estrus and the effects on sow fertility and piglet growth. Litter size was equalized within parity (11.5 ± 1.1 piglets) at d 2 after farrowing. At d 18, sows were assigned to 1 of 5 treatments (n = 26 to 28) based on parity, farrowing date, and suckled litter size. Treatments were: 1) control; 2) sows that were paired within parity and placed in adjacent stalls, on d 18 all but 5 of the lightest piglets were weaned, and the remaining piglets were combined and alternated between sows at 12 h intervals until d 25 (ALT); 3) piglets separated from sows for 12 h/d from d 18 to 25 (SEP); 4) all but the 5 lightest piglets weaned on d 18, splitweaning (SW); and 5) piglets separated from sows for 24 h on d 18 (24HR). Controls were weaned at d 21 with other treatments weaned at d 25. All sows were provided nose-to-nose contact with a mature boar for 5 min/d from d 18 until weaning without removing them from farrowing crates. Creep feed and water were provided from d 14 to weaning. Offspring ADG was recorded to market for 2 farrowing groups. Sow backfat and BW losses during lactation were similar across treatments. Of the 106 sows subjected to reduced suckling, 80 (76%) expressed estrus during lactation. The SEP and 24HR sows were in estrus earlier (P 0.05) on final BW or carcass composition were observed for the reduced suckling treatments. Altered suckling treatments differed in their ability to induce lactational estrus and their impact on gain immediately post-weaning. However, no benefits were observed for pig growth to market weight.

Luteinizing hormone and growth hormone secretion in early lactating Spanish beef cows

The episodic release of luteinizing hormone (LH) and growth hormones (GH) was studied in three suckling regimens and two breeds of Spanish suckled cows. Parda de Montaña (PA) cows (n = 21) were assigned to once-daily, twice-daily or ad libitum (ADLIB) suckling. Pirenaica (PI) cows (n = 7) were used to evaluate the breed effect in twice-daily suckling. Coccygeal blood samples were collected twice weekly during lactation to determine the interval from calving to first ovulation through peripheral progesterone. On day 32 ± 3 post-partum, jugular blood samples were drawn at 15 min intervals during 8 h to analyse circulating LH and GH. The interval to first ovulation was greater in PA cows suckling ADLIB than in restricted suckling treatment (RESTR1), whereas in RESTR2 it did not differ from the other two treatments. There were no differences between PA and PI cows in the interval to first ovulation. RESTR1 cows showed a tendency to have shorter LH peak widths than ADLIB cows. PA cows showed a tendency to have longer LH peak widths than their PI counterparts. There were no differences across treatments or breeds in any of the GH measures of secretion. The LH release was more affected by breed than by suckling frequency, whereas that of GH was not influenced by any of these parameters. The variables that best allowed discrimination between ADLIB and restricted nursing systems were the interval to post-partum first ovulation, LH peak number and the mean GH concentration.

Desempenho de cordeiras Bergamácia submetidas a dois sistemas de desmama

This study used 26 Bergamasca ewe lambs weaned at 60 days of age and separated into 2 groups – Artificial suckling: 10 ewes separated from their dams 48 hours after delivery and fed with cow’s milk; Controlled suckling: 16 ewe lambs remained with their dams at pasture during the day and then separated at night, returning after morning milking. Following weaning, both groups were confined until they reached 38.6 kg average weight, and then separated into two types of treatment: Pasture rearing: 5 ewes from artificial suckling + 8 ewes from controlled suckling; Confined rearing: 5 ewes from artificial suckling + 8 ewes from controlled suckling. The experimental design was a 2 x 2 factorial, randomized. Average daily milk production for artificial suckling (0.318 kg) was higher than controlled suckling (0.256 kg). The economic return of the controlled suckling treatment was 8.13% higher than for artificial suckling. With regard to the pasture rearing and confined rearing treatment systems, there was no estrus for pasture rearing during experimental period. There was no difference between the weaning systems with regard to eggs per gram. The weaning system influenced the milk production of primiparous females.

Effect of body condition and suckling restriction with and without presence of the calf on cow and calf performance

Nutrition and suckling are largely recognised as the most important factors affecting the postpartum period and consequently the reproductive efficiency of beef cattle. The aim of this study was to evaluate the effects of body condition score (BCS) and suckling restriction with and without the presence of the calf on milk production, reproductive efficiency and calf performance. Sixty-three crossbred (Angus × Hereford) multiparous cows were managed to maintain different BCS at calving and thereafter (low vs moderate; L, n = 31 and M, n = 32). Within each group of BCS (L and M) at week 9 postpartum (66 ± 0.88 days postpartum) cows were assigned to three suckling treatments (ST): (i) suckling ad libitum (S, n = 20); (ii) calves fitted with nose plates during 14 days remaining with their dams (NP, n = 22); and (iii) calves were completely removed from their dams for 14 days, and thereafter returned (CR, n = 21). Milk production was assessed by milking procedure at Day 65 (the day before onset of ST) and every 20–22 days until the end of the experiment. Cows were bled via jugular venipuncture every 28 days from Day –98 (Day 0 = calving) until Day 66. From Day 66 cows were bled every 7 days until the end of the mating period (Day 128). Concentrations of progesterone, non-esterified fatty acids and β-hydroxybutyrate acid and insulin were measured. Presence of corpus luteum (CL) was recorded and maximum follicle diameter was measured in all cows from the onset of the ST (Day 66) and during the following 4 weeks (until Day 94) in a weekly frequency. At Day 94, more cows (P &lt; 0.001) in NP and in CR had CL compared with S cows (68, 57 and 21% for NP, CR and S, respectively). At that time, more cows in M-BCS presented CL than cows in L-BCS (77 vs 25; P &lt; 0.0001). Within M-BCS, there were no differences in milk production between ST groups, while L-BCS cows with NP or CR produced less milk than S cows. Calf liveweight at weaning was 159.3 ± 3.1, 150.1 ± 2.9 and 147.0 ± 3.1 kg for S, NP and CR, respectively (P &lt; 0.001). Suckling restriction with and without the presence of the calf had similar effects on reproductive performance, milk production and calf growth, while BCS interacted with ST to influence milk production. These results indicate that temporary suckling restriction could be an excellent management tool to increase reproductive performance of cows in moderate condition.

Effects of intermittent suckling and creep feed intake on pig performance from birth to slaughter1

An experiment was conducted to determine if the improved creep feed intake observed during intermittent suckling (IS) is important for postweaning performance. Therefore, creep feed intake of litters was assessed, and within litters, eaters and noneaters were distinguished using chromic oxide as an indigestible marker. Batches of sows were suckled intermittently (IS, 7 batches; n = 31) or continuously (control, 7 batches; n = 31). In the IS group, litters were separated from the sow for a period of 12 h/d (0930 to 2130), beginning 11 d before weaning. Litters were weaned at 4 wk of age. Litters had free access to creep feed from 1 wk of age onward. Five days after weaning, the piglets were moved as a litter to weanling pens. At 8 wk of age, 2 barrows and 2 gilts were randomly chosen from each litter and moved to a finishing facility. Feed intake was improved by IS during the last 11 d of lactation (IS, 284 +/- 27 vs. control, 83 +/- 28 g/piglet; P < 0.001) and after weaning during the first (IS, 201 +/- 24 vs. control, 157 +/- 25 g x piglet(-1) x d(-1); P < 0.05) and second (IS, 667 +/- 33 vs. control, 570 +/- 35 g x piglet(-1) x d(-1); P < 0.05) wk. Thereafter, no differences were found to slaughter. Weaning BW was lower in IS litters (IS, 7.1 +/- 0.01 vs. control, 8.1 +/- 0.01 kg/piglet; P < 0.05), but 7 d after weaning BW was similar (IS, 8.5 +/- 0.2 vs. control, 8.7 +/- 0.2 kg/piglet; P = 0.18), and no differences were found to slaughter. The percentage of eaters within a litter was not increased by IS during lactation (IS, 23 +/- 4.5% vs. control, 19 +/- 4.1%; P = 0.15). Weaning BW did not differ between eaters and noneaters (eater, 7.7 +/- 0.1 vs. noneater, 7.5 +/- 0.08 kg/piglet; P = 0.63). From 1 until 4 wk after weaning, piglets that were eaters during lactation had heavier BW than noneaters (eater, 20.3 +/- 0.3 kg vs. noneater, 18.2 +/- 0.2 kg; P < 0.05). The influence of eating creep feed during lactation on BW and ADG and the influence of suckling treatment never showed an interaction. We conclude that IS increases ADFI during lactation on a litter level and improves ADG in the first week and ADFI in the first and second weeks after weaning. No long-term effects on ADFI or ADG were observed throughout the finishing period. In the current experiment, in which creep feed intake was low, the percentage of eaters within a litter was not increased, suggesting that creep feed intake of piglets that were already eating was stimulated by IS. Further, piglets that were eaters during lactation had heavier BW up to 4 wk after weaning.

Weaning strategies to improve the performance of sows and their progeny under smallholder farming conditions

The effect of restricted suckling and split weaning on the reproductive performance of dams and subsequent performance of their litters was studied in an experiment involving 48 Landrace x Large White sows of second and third parity. The sows and their litters were allocated to four treatments as follows: separation to allow either one or two 30 minute periods of suckling per day, reduction of litter size by weaning all piglets attaining 6 kg body weight and a control in which suckling was not restricted. Treatments commenced when piglets attained four weeks of age and were weaned at eight weeks of age. Restricted suckling resulted in an increased creep feed intake by the piglets. Piglets that were suckled once a day consumed 8.76 kg creep feed during the experimental period compared to 8.49, 8.35 and 8.21 kg for split weaning, twice a day suckling and the control, respectively. All intakes were significantly different. No differences were observed between treatments in total weight gain over the four week period. Sows in the control treatment had an average wean to oestrus interval (WOI) of 17 days. Restricting piglets to suckling once or twice a day, or split weaning had a positive effect of significantly reducing the WOI compared to the control. A number of sows exhibited oestrus during lactation, with the sows in the twice a day suckling treatment having a larger percentage than those in the other treatments. Restricting suckling and split weaning have an advantage of improving the reproductive performance of the sows without compromising piglet survival or growth. We recommend restricting piglet suckling to twice a day, and weaning of all piglets attaining six kg live weight.

Manipulation of lactation and suckling on the resumption of postpartum reproductive activity in Damascus goats

The reproductive activity of Damascus goats was studied in does that were not allowed to mate (non-lactating does) (Group C) and lactating does with different suckling treatments (Groups A and B). Time resumption of sexual activity was not significantly different between lactating and non-lactating does or between does’ groups of different suckling treatments. All does started to demonstrate estrous behavior during autumn (September). In Groups A, B and C the mean length of the estrous cycle was 19.0±0.6, 19.5±0.3 and 22.0±2.0 days, duration of the estrous period 29.6±3.0, 31.0±5.3 and 25.3±5.8 h, mean corpus luteum (CL) counts 1.6±0.2, 1.8±0.2 and 1.8±0.3, while mean litter size was 1.1±0.1, 1.2±0.2 and 1.3±0.5, respectively. In the three groups an increase in the plasma progesterone concentrations started from summer (mid-June), indicating the occurrence of one or more ovulatory anestrus (silent ovulation). Plasma prolactin levels were higher ( P<0.01) in lactating does than in non-lactating does and at 4 weeks postpartum. Moreover, prolactin levels were significantly higher ( P<0.01) in does suckling their kids than in does being machine milked. Plasma progesterone levels during postpartum were negatively significantly correlated with prolactin levels. The study demonstrated that lactation and suckling lengths have no effect on the resumption of postpartum sexual activity in Damascus goats and that season is the major factor controlling the ovarian activity.

Restricted suckling of tropical dairy cows by their own calf or other cows' calves.

The objective of this study was to compare restricted suckling of tropical cows by their own or another cow's calf with artificial rearing of the calves and no suckling. In Exp. 1, cows were mechanically milked twice daily, after which for 15 min they were either suckled by their own calf (Treatment O) or multiple-suckled by other cows' calves (Treatment M) or unsuckled, with the calves reared artificially (Treatment A). Machine milk yield was similar for the three treatments, but in the two suckling treatments the additional milk consumed by the calf increased (P = 0.02) total production (2,682, 2,634, and 2,336 kg/lactation for Treatments O, M, and A, respectively). Machine milk fat concentration was reduced (P = 0.05) by suckling (2.90, 3.07, and 3.20% for Treatments 0, M, and A, respectively), but the milk sampled just before suckling (to represent that taken by the calves) had a high fat concentration (mean 7.9%). Machine milk somatic cell count was also reduced (P = 0.05) by suckling, from 106,000/mL (Treatment A) to 85,000/mL (Treatment M) and 95,000 (Treatment O). Cows suckling their own calf lost more weight and body condition than cows whose calves were reared artificially, with multiple-suckled calves intermediate. Cows suckling their own calf had postpartum interval to first estrus increased (P = 0.01) by 31 d and conception rates to first service of 44% compared to 77% for the other two treatments (P = 0.01). The growth of the suckled calves was compared with that of the artificially reared calves, which were given recommended milk allowances. The artificially reared calves consumed more milk and concentrates, which were available ad libitum to all calves, and gained (P = 0.03) 0.07 kg/d more weight than suckled calves. A second experiment determined that suckling once daily did not reduce reproductive performance compared to artificial rearing. We conclude that suckling cows twice daily increases total milk production but reduces body weight in early lactation. Cows suckling their own calves have reduced reproductive performance compared to those suckling other calves or reared artificially.

Ovulation of the first dominant follicle arising after day 21post partumin suckling beef cows

AbstractThe effects of body condition score (BCS) of 2·0 or 3·0 units at calving (low v. moderate), post-partum energy intake at 0·6 or 1·0 MJ metabolizable energy (ME) per day per kg M0·75 (low v. high) and unrestricted or restricted (once daily) suckling on the ability of cows to ovulate were studied in a 2 ✕ 2 ✕ 2 factorial design with each treatment replicated eight times. Calf isolation and restricted suckling were imposed shortly after selection of the first dominant follicle (DF) to emerge after day 21 post partum. The episodic release of LH (sampled at 15-min intervals for 10 h) was determined 48 h before and 48 h after the day calf isolation and restricted suckling commenced. Additional blood samples were collected weekly for plasma insulin determination. The mean interval from calving to first ovulation was shorter for cows in moderate than low BCS at calving (47·8 v. 57·1 days, s.e.d. = 4·50, P &lt; 0·05), and for cows suckling once daily than for those with unrestricted suckling (42·9 v. 62·0 days, s.e.d. = 4·50, P &lt; 0·001). Post-partum nutrition did not affect this interval. Mean LH pulse frequency prior to the start of restricted suckling was higher for cows of moderate than low BCS at calving (3·2 v. 1·6 pulses per 10 h, s.e.d. = 0·60, P &lt; 0·05). Subsequently, LH pulse frequency was higher for cows suckling once daily than for those with unrestricted suckling (4·0 v. 2·2 pulses per 10 h, s.e.d. = 0·82, P &lt; 0·05). More cows in moderate than low BCS ovulated the first DF to emerge after day 21 post partum (within 4 to 6 days) in response to restricted suckling (69 v. 25%, P &lt; 0·05). LH pulse frequency prior to restricted suckling increased (P &lt; 0·05) with plasma insulin concentration (categorized as low, &lt; 5; moderate, 5 to 8; and high, &gt;8 mIU per l). There were indications of interactions between suckling treatment and BCS (P &lt; 0·08), and suckling treatment and plasma insulin concentration (P &lt; 0·06), on LH pulse frequency, which suggested that calf restriction could alleviate the suppressive effects of under nutrition on episodic LH release. Amongst cows suckling once daily, the non-ovulating animals had fewer LH pulses prior to restricted suckling and smaller, slower growing DF, indicating an inability of the DF to respond to increased LH pulse frequency following calf restriction. Cows of moderate BCS, particularly those with moderate to high levels of plasma insulin (³ 5 mIU per l), responded favourably to restricted suckling. In contrast, excessively thin cows with low plasma insulin concentrations (&lt;5 mIU per l), that had most to gain from restricted suckling, responded poorly.

Production responses of tropical crossbred cattle to supplementary feeding and to different milking and restricted suckling regimes

The relationships between cow nutrition, restricted suckling and milking patterns and their effect on milk yield, milk composition and calf growth were examined under tropical conditions in south east Mexico. Eleven Bos indicus× Bos taurus cows, 14 days postpartum, with calves weighing on average 37 kg were used in a change-over experimental design. All cows were fed Cynodon nlemfuensis hay ad libitum, and either 4.0 kg Leucaena leucocephala, 2.0 kg sorghum grain and 0.25 kg sugar-cane molasses on a fresh weight basis (L1), or twice this amount of the same supplement (L2). The calves were offered the same hay ad libitum in addition to suckling milk. The milking/restricted suckling treatments were: twice-daily milking with suckling after morning milking (2×AM), and once-daily milking in the morning with afternoon suckling (1×PM). The two regimes were examined at L1 and L2 feeding levels. A suckling time of 30 min was allowed at each suckling occasion. For 2×AML1, 2×AML2, 1×PML1 and 1×PML2, respectively saleable milk yields (SMYs) (kg/day) were 5.43, 5.99, 3.47, 4.09 (S.E.M. 0.174); calf suckled milk (CSM) (kg/day) 1.36, 1.46, 3.14, 3.43 (S.E.M. 0.160); and total milk yield (kg/day) 6.79, 7.46, 6.62, 7.53 (S.E.M. 0.226). For SMYs, fat contents (g/kg) were 30.0, 29.4, 29.0, 28.7 (S.E.M. 1.11), respectively, and for CSM 59.6, 63.4, 38.8, 42.4 (S.E.M. 2.46). Protein contents (g/kg) for SMYs were 27.5, 29.1, 29.3, 30.4 (S.E.M. 0.67) and for CSM 27.9, 28.4, 29.1, 30.3 (S.E.M. 0.81). Total food intakes of cows were 10.84, 12.12, 10.99, 12.16 (S.E.M. 0.331) kg DM/day. Calf growth rates were, respectively, 0.17, 0.20, 0.41, 0.52 (S.E.M. 0.029) kg/day, and hay DM intake 0.58, 0.49, 0.41, 0.34 (S.E.M. 0.040) kg/day. It was concluded that level of supplementation and restricted suckling and milking regimes could both be used to manipulate TMY, SMY and calf performance.

Effect of calf isolation on follicular wave dynamics, gonadotropin and metabolic hormone changes, and interval to first ovulation in beef cows fed either of two energy levels postpartum.

The effects of postpartum energy intake, restricted suckling, and cow-calf isolation on concentrations of LH, FSH, growth hormone, and insulin-like growth factor-I (IGF-I) and on postpartum anestrous interval were determined by randomly allocating beef cows with a mean body condition score of 2.3 +/- 0.1 to receive either 80 MJ metabolizable energy (low-energy diet [L]; n = 51) or 120 MJ metabolizable energy (high-energy diet [H]; n = 52) per cow per day from calving. At 30 days postpartum, cows within diet were randomized to 1) have continued full access to their calves from birth to weaning (ad libitum suckling: ADLIB), 2) be suckled once-daily with their calves penned adjacent (restricted suckling, adjacent: RESADJ), 3) be isolated from all calves except for a once-daily suckling period (restricted suckling, isolated: RESISO). The mean postpartum interval was similar (p > 0.10) for L and H cows (62 and 63 days, respectively). RESADJ cows had a shorter (p < 0.05) postpartum interval than ADLIB cows, and RESISO cows had a shorter interval (p < 0.05) than RESADJ cows, with all effects independent (p > 0.10) of diet. FSH secretion pattern was not affected by diet, suckling treatment, sequential follicle wave number, or follicle wave retrospectively realigned to emergence of first ovulatory wave. Within 5 days of suckling restriction and calf isolation, the number of LH pulses increased from 0.18 to 0.48 pulses per hour (p < 0.05). Both mean LH and the mean number of LH pulses increased linearly (p < 0.01) during the six follicle waves up to the first ovulatory wave. From 80 days before, until the time of, first ovulation, growth hormone decreased (p < 0.05) while IGF-I increased (p < 0.05), irrespective of treatment. The results indicate that the "suckling effect" in beef cows is the major factor affecting the duration of the postpartum interval and suggests that the maternal bond is more important than suckling in regulating LH pulse frequency, the key endocrine factor determining whether or not a dominant follicles ovulates. Removal of the suckling effect resulted in a rapid increase in LH pulse frequency, which was not dependent on level of postpartum nutrition, at least within the nutritional limits of this study. Mean concentrations of FSH, unlike LH, did not vary with follicle wave number, suggesting that lack of FSH is not a major factor delaying the resumption of ovulation in postpartum beef cows.

Influence of dietary supplementation and partial suckling on body weight and on lactation and reproductive performance of primiparous Boran (Bos indicus) cows in Ethiopia

SummaryThis study was conducted in the central highlands of Ethiopia during 1990–92 to examine the effects of diet and partial suckling on lactation and reproductive performance of Boran (Bos indicus) cows. Primiparous Boran cows were allocated to dietary supplementation or no supplementation with either milking or partial suckling based on body weight at calving. All cows received grass hay ad libitum and the supplemented groups were provided with additional concentrate feed which supplied 222 g/kg DM crude protein and 10 MJ/kg DM energy. Calves were weaned at 8 weeks of age. Mean (±S.E.) dam calving and calf birth weights were 314±11·4 and 25±0·6 kg. Body weights at first postpartum oestrus and at conception were not affected by suckling. Supplemented cows however, were heavier at first oestrus (P = 0·06) and at conception (P &lt; 0·01) than non-supplemented cows. Lactation length was longer (P &lt; 0·01) and mean daily milk yield higher (P &lt; 0·001) in suckled than in milked cows. Diet, however, did not influence either lactation length or daily milk yield. In suckled cows, mean daily milk yield declined sharply after weaning (week 9) and was lower by 38 and 43% of week 8 production in the supplemented and non-supplemented groups, respectively. The overall mean lactation yield was 212·4±64·6 litres; with a significant (P &lt; 0·05) diet × suckling interaction effect. Concentrations of milk fat, total protein and total solids were not affected by either diet or suckling treatment. The postpartum anoestrus interval was longer (P &lt; 0·01) in non-supplemented than in supplemented cows, but did not differ between suckled and milked cows. The percentage of cows cycling by 150 days postpartum was higher (P &lt; 0·05) in supplemented than in nonsupplemented and in milked than in suckled (P &gt; 0·05) cows. By this interval, a higher (P &lt; 0·05) percentage of supplemented-milked (90%) cows cycled than in the other three treatment groups (48·5%). Pregnancy from the first insemination ranged from 45·5 to 63·6% in the four treatment groups. It was concluded that although partial suckling extended the postpartum anoestrus interval, lactation length and milk yield were improved. The negative effects of partial suckling on postpartum reproduction could be overcome with the appropriate dietary supplementation. The economic tradeoff between dietary supplementation, milk yield and reproduction has to be determined in partially suckled cows.

Effect of multiple suckling in early lactation on the performance of May-born calves

ABSTRACTIn three experiments, 16, 24 and 22, May-calving Aberdeen Angus × British Friesian cows were subjected either to single suckling of their natural calves or to single suckling in addition to ‘foster’ suckling for the first 8 to 9 weeks of lactation. Foster suckling was achieved by the removal of cows from pasture twice daily and suckling of male Friesian calves while cows were confined in a creep. Average milk yield per cow removed by foster suckling and milk secretion rates of individual cows were measured at intervals and cows were grazed at equal grazing pressure. Single plus foster suckling increased estimated total yield over single suckling proportionately by 0·55, 0·18 and 0·34 in the three experiments respectively. After foster calves were weaned, milk secretion rate of foster-suckling cows was always higher than that of naturally suckling cows. In addition to a mean yield of about 300 kg milk per cow to foster calves, single plus foster suckling increased calf gain in the natural calves in each experiment although the increases were not significant. The apparent conversion of extra milk consumed by natural calves in the single plus foster suckling treatment was generally low in relation to figures quoted in the literature.

Effect of forty-eight-hour calf removal, once- or twice-daily suckling and Norgestomet on beef cow and calf performance

Trials were conducted in 1980 and 1981 to evaluate the effects of once-daily suckling, twice-daily suckling, 48-h calf removal, and Norgestomet on performance of spring-calving cows and their calves. Eighty-three and 73 Polled Hereford and 29 and 42 Simmental-cross cows were utilized in 1980 and 1981, respectively. Cows were allotted by age, breed, calving date and winter nutrition treatment to one of four groups: 1) once-daily suckle for 24 d starting 11 d before the beginning of the breeding season, 2) twice-daily suckle (same time frame as 1), 3) 48-h calf removal ending immediately before the breeding season, 4) calves remained with cows (controls). One-half.of each group was implanted with Norgestomet b b Norgestomet (17 acetoxy-11 methyl-19 nor-preg-4-ene-3, 20-dione), a synthetic progestogen, was provided by G. D. Searle & Co., Chicago, IL. from 11 until 2 d before the start of the breeding season. Once- and twice-daily suckling increased (P<0.05) the percentage of noncycling cows showing estrus the first 3 wk after the start of treatment. Pregnancy rates for the breeding season were higher (P<0.1) in the once-daily suckle and 48-h calf removal groups for cows that had not exhibited estrus before the beginning of treatment. Norgestomet increased (P<0.05) the percentage of cows showing estrus within 3 wk after the start of treatment within the 48-h calf-removal and control groups. Milk production was not affected (P>0.1) by suckling treatment. Calf weight gains during suckling treatment were greater (P<0.05) in control and twice-daily suckled calves than in 48-h calf removal or once-daily suckled calves. Suckling treatment did not affect (P>0.1) adjusted weaning weights of calves or frequency and duration of suckling recorded 2 wk after the end of suckling treatment.

Effect of suckling intensity on human growth hormone binding, biochemical composition and histological characteristics of ovine mammary glands

Suckling both, or only one contralateral mammary gland during 15 days postpartum was utilized to study lactogenic hormone binding to mammary microsomal membranes and quantitative mammary morphology in ewes. Binding of radiolabeled human growth hormone was specific for lactogenic hormones. Non-radiolabeled human growth hormone, ovine and bovine prolactin and human placental lactogen effectively competed with radiolabeled human growth hormone for binding sites but ovine and bovine growth hormone were completely ineffective. Specific binding of radiolabeled human growth hormone to 600 μg of membrane protein averaged 23 ± 3% in all lactating glands. Neither days postpartum nor treatment of contralateral mammary glands substantially altered hormone binding in lactating glands. Specific human growth hormone binding (6 ± 0.5%) in non-suckled glands (15 days postpartum both udder halves) was significantly lower (P<0.01) than in lactating tissue but only a moderate and variable reduction in specific binding was measured in membranes from glands non-suckled for 15 days but contralateral to a suckled gland (14 ± 4%). Specific binding was approximately doubled in assays with 600 compared with 300 μg of membrane protein and the pattern of binding among variously suckled glands was not changed by treatment of membranes with 4 M MgCl 2 prior to assay. Most secretory cells from all lactating glands had rounded, basally displaced nuclei, apical fat globules, secretory vesicles and abundant densely stained basal cytoplasm (ergastoplasm). Alveolar lumenal area was maximal (50% of tissue area) and stromal tissue area was minimal. After 15 days of non-suckling (both udder halves) mammary cells were engorged with lipid, ergastoplasm was reduced and nuclei were irregularly shaped and randomly displaced compared with lactating tissue. In addition, lumenal area was reduced and stromal tissue more evident. Lack of suckling for 5 days had little apparent effect on mammary cytology. Like lactogenic hormone binding, mammary tissue morphology was only moderately altered by 15 days of non-suckling when the remaining gland was suckled. RNA concentration was lowest (2.1 ± 0.3 mg/g) in mammary tissue from ewes in which neither gland was suckled for 15 days postpartum but non-suckling interval had no significant effect when contralateral glands were suckled. DNA concentration was not significantly influenced by suckling treatments. Relative lactogenic hormone binding closely corresponded to changes in cytological and biochemical indices of secretory cell function.

Variation in chromium excretion in suckled cows at pasture

ABSTRACTThe diurnal cycle of chromium excretion was estimated over the last 24 h of a 13-day period in which nine single- and nine double-suckled cows were dosed twice daily (10.00 and 16.00 h) with shredded Cr2O3 paper. All faecal passages voided were sampled and analysed for chromium. Rectal samples were also taken at 10.00 and 16.00 h during this period. Sources of variation in the patterns of excretion that could be attributed to cow live weight, daily milk yield or total weight of the calf or calves being reared were also investigated.Mean faecal Cr concentrations followed a cyclic pattern which was significantly described by a sinusoidal equation.The estimated fundamental period (0·1334 rad/h) did not differ significantly from the theoretical value (2π/48 = 0·1309 rad/h). Fitting the model for each cow explained from 0·61 to 0·99 of the variation in faecal Cr concentration. Differences between suckling treatments in predicted faecal Cr content at discrete 2-h intervals over the 24-h period were not significant. Equations for heavier cows had lower constant terms, consistent with lower faecal Cr contents expected as a consequence of higher intakes. Differences in cow milk production and total calf live weight being reared were related to the pattern of Cr excretion (P &lt; 0·05) but the reasons for these effects were not readily apparent. Mean Cr concentration in rectal samples was significantly correlated (r = 0·916) with mean 24-h faecal Cr content predicted from the model.