Cow-calf Pairs Research Articles

The impact of elective caesarean section on colostrum characteristics in double-muscled Belgian Blue cows

Identification of factors associated with the quality and quantity of colostrum production has always been a major challenge in cattle industry. In purebred double-muscled Belgian Blue (BB) cows, parturition is mainly performed by elective caesarean section (CS; >90%). However, the CS itself may influence colostrum production characteristics. The present study aimed to evaluate the impact of maternal and newborn calf factors and the duration of the procedure of CS on the quality and quantity of colostrum production in BB cows. The dataset includes 551 records of cow-calf pairs that were presented for an elective CS at the Ghent University veterinary clinic between 2017 and 2019. The quality (measured via a colostrum densimeter) and the quantity (measured via a standard volume scale) of colostrum were measured within 30 min after the end of the CS. Fixed effects were fitted in mixed linear regression models to test for their potential association with colostrum quality (specific gravity; SG) and quantity (liters), and generalized mixed-effects models were constructed to test the associations of fixed effects with the optimal colostrum production index (yes vs no) based on an adequate supply of both colostrum quality and quantity. The fixed effects tested were parity, the gender of the calf, birth weight, duration of CS (min), and season of birth. Our results show that parity (primiparity), duration of CS (longer CS), and calving season (summer) had a significantly negative impact on colostrum production. Concluding, both colostrum quality and quantity can be influenced by intrinsic and extrinsic factors (including duration of CS), which should be considered while feeding newborn calves delivered via CS.

Towards an enhanced management of recreational whale watching: The use of ecological and behavioural data to support evidence-based management actions

Recognition of the potential disturbance from whale-based tourism has stimulated the discussion of whether whale watching remains ‘no take’. Here we use observations and passive acoustic surveillance of tourism activities of foraging gray whales (Eschrichtius robustus) on the west coast of Vancouver Island to better understand the pressures on whales that are repeatedly subject to aerial and vessel-based viewing. Pressure from the fleet was greatest for low prey years, whereby fewer whales were subject to a greater number of encounters with whale watching vessels. The pressure on operators for close encounters was also greater during these years. The acoustic recordings found that whale watching vessels shaped the soundscape, with a distinct diurnal pattern. Acoustic reactions by the whales were also noted. Cow-calf pairs showed increased calling rate in the presence of vessels in the feeding bay, with calling rate of single foraging whales increasing as vessel number, particularly those engaged in whale watching, increased. These responses have implications for energetics, communication success. The implications of acoustic disturbance from whale watching has yet to be well defined, but it is only one of many stressors that gray whales are subject to. The results of this study lead us to argue for greater evidence-based management of whale watching; restrictions on encounters; noise emission limitations; requiems for the whales, and a greater interpretative component for passengers. The aggregate and cumulative effects of disturbance should also be emphasized in vessel-whale interaction guidelines, with the most vulnerable individuals removed from the viewing resource altogether.

Investigating cow-calf contact in a cow-driven system: performance of cow and calf.

In this research communication we describe the performance of dairy cow-calf pairs in two cow-driven CCC-systems differing in cows' access to the calves through computer-controlled access gates (smart gates, SG). We investigated cows' machine milk yield in the automatic milking system (AMS), calf growth, and intake of supplemental milk and concentrate. Two groups each with four cow-calf pairs were housed in a system with a cow area, a calf creep and a meeting area. SG's controlled cow traffic between the meeting area and the cow area where cows could obtain feed, cubicles and the AMS. Calves had ad libitum access to supplemental milk and concentrate. During the suckling phase of 31 d, cow access to the meeting area was free 24 h/d (group 1) or restricted (group 2) based on milking permission. Following the suckling phase, cow access was gradually decreased over 9 d (separation phase). During the suckling phase, cows' machine milk yield (mean ± sd) in the AMS was 11.4 ± 6.38 kg/d. In the separation phase, the yield increased to 25.0 ± 10.37 kg/d. Calf average daily gain (ADG) was high during the suckling phase: 1.2 ± 0.74 kg. During the separation phase, ADG decreased to 0.4 ± 0.72 kg which may be related to a low intake of supplemental milk. Calves' concentrate intake increased with age, and all calves consumed >1 kg/d after separation. We conclude that cows nurse the calf in a cow-directed CCC system well resulting in high ADG, and AMS milk yields were, at least, partially maintained during the suckling phase. Although the AMS yields increased in response to separation, calf ADG was decreased. A low sample size limits interpretation beyond description but provides a basis for hypotheses regarding future research into CCC-systems.

Investigating cow-calf contact in cow-driven systems: behaviour of the dairy cow and calf.

Research is needed on how technology can facilitate cow-calf contact (CCC). This research communication describes the behaviour of dairy cow-calf pairs in two cow-driven CCC-systems differing in cows' access to the calves through computer-controlled access gates (smart gates, SG). Specifically, cow traffic through SG when visiting their calves, allogrooming, suckling and cross-suckling, cows' eating and resting behaviour and finally vocal response to separation were assessed. After 3 d in an individual calving pen, pairs (n = 8) were moved to the CCC compartment with a cow area, a calf creep and a meeting area. During the next 31 d calves could suckle the cows whenever they visited the meeting area (suckling phase). Cows had free (group 1, n = 4 pairs) or restricted access to the calves based on previous activity in the automatic milking system (group 2, n = 4 pairs). SG's controlled cow traffic between the meeting area and the cow area, in which the cows could access resources such as feed, cubicles, and the automatic milking system. Following the suckling phase cow access into the meeting area was gradually decreased over 9 d (separation phase). During the suckling phase, cows paid frequent and short visits to their calves. Pairs spent in total approximately one h/d suckling and allogrooming. However, the duration and frequencies of these events varied among pairs and groups, as did the vocal response to separation. Restricted access - cows performed more (unrewarded) attempts to visit the calves who cross-suckled more. Collectively, free access to the calves may have been more intuitive and welfare friendly. Although a low sample size limits interpretation beyond description and enabling hypothesis formulation for future research, the results indicate that the cow is motivated to visit her calf, albeit through a SG, thus facilitating particular behaviours for which cow-calf pairs are highly motivated.

Low moisture, cooked molasses blocks: A limited intake method for supplementing trace minerals to pre-weaned calves

Two studies were conducted at the Range Cattle Research Education Center (Ona, FL) to evaluate the preference of beef calves for different sources of trace minerals in low moisture cooked molasses blocks (MB; Exp.1) and to evaluate the effects of optimal trace mineral status at weaning while investigating the use of free-choice, MB in a limited intake creep-feeding system (Exp. 2). In Exp. 1, eighteen early-weaned calves (120 d and 185 kg BW) were randomly assigned to 6 bahiagrass pastures (Paspalum notatum; n = 3/pasture). Treatments consisted of 3 MB formulations containing 550, 1650 and 2200 mg/kg of Cu, Zn and Mn from 3 different sources (hydroxychloride, organic and sulfate). Calves had continuous and simultaneous access to each of the 3 MB treatments. Intake was greatest (P = 0.04) for MB fortified with hydroxychloride and was similar between organic and sulfate (0.35, 0.27, and 0.28 kg/d, respectively). In Exp. 2, forty-eight cows with heifer calves (n = 24 pairs/year) were randomly assigned to 12 bahiagrass pastures (n = 2 cow-calf pairs / pasture). Treatments consisted of 2 MB formulations; (1) Control = no added minerals; or (2) Fortified = 550, 1650, and 2200 mg/kg of Cu, Zn, and Mn from hydroxychloride sources. Sodium, Ca, Se, Co, and I were formulated into the Fortified MB treatment at levels to meet NASEM recommendations. Following weaning, calves were transferred to fully covered individual pens for a 30-d evaluation. Molasses block intake was greater (P = 0.01) among calves assigned to Control vs. Fortified treatment (0.35 vs 0.21 kg/d). A treatment × year effect was detected (P ≤ 0.01) for liver trace mineral concentrations, where calves assigned to Fortified vs. Control treatment had greater concentrations of Co, Cu, Mn, and Se at weaning in year 1, but not in year 2. For the Fortified treatment, MB intake was 38 % less in year 1 vs. 2, which correlated with less liver Cu (r = 0.52; P < 0.01) and Se (r = 0.79; P < 0.01). In summary, MB supplements, fortified with hydroxychloride sources of Cu, Zn, and Mn, are preferred by calves when compared to other mineral sources. The supplementation of pre-weaned calves with mineral-fortified low moisture, cooked MB was effective as a limit-feeding vehicle for trace mineral delivery; however, calf mineral status at weaning is dependent upon adequate supplement intake.

Utilizing an electronic feeder to measure individual mineral intake, feeding behavior, and growth performance of cow-calf pairs grazing native range.

Crossbred Angus cow–calf pairs (n = 28 pairs) at the Central Grasslands Research Extension Center (Streeter, ND) were used to evaluate an electronic feeder to monitor individual mineral intake and feeding behavior and their relationship with growth performance and liver mineral concentrations. Cows and calves were fitted with radio frequency identification ear tags that allowed access to an electronic feeder (SmartFeed system; C-Lock Inc., Rapid City, SD) and were provided ad libitum minerals (Purina Wind and Rain Storm, Land O’Lakes, Inc., Arden Hills, MN). Mineral intake, number of visits, and duration at the feeder were recorded over a 95-d monitoring period while pairs were grazing native range. Liver biopsies were collected from a subset of cows on the final day of monitoring and analyzed for mineral concentrations. Data were analyzed with the GLM procedure in SAS for mineral intake and feeding behavior with age class (cows vs. calves), intake category (high vs. low), and the interaction between class and category in the model. Correlations were calculated among cow feeding behavior and calf intake and growth performance with the CORR procedure, and a comparison of liver mineral concentrations among cows of high (>90 g/d; average 125.4 g/d) and low (<90 g/d; average 33.5 g/d) mineral intake was performed using the GLM procedure. High-intake calves (>50 g/d; average 72.2 g/d) consumed greater (P < 0.001) amounts of minerals than low-intake calves (<50 g/d; average 22.2 g/d) intake calves. Cows and calves attended the mineral feeder a similar (P = 0.71) proportion of the days during the experiment (overall mean of 20%, or once every 5 d). On days calves visited the feeder, they consumed less (P < 0.01) minerals than cows (222 ± 27 vs. 356 ± 26 g/d, respectively). Over the grazing period, calves gained 1.17 ± 0.02 kg/d, whereas cows lost 0.35 ± 0.02 kg/d. Calf mineral intake was correlated with cow duration at the mineral feeder (r = 0.403, P = 0.05). Cows with high mineral intake had greater (P < 0.01) concentrations of Se (2.92 vs. 2.41 ug/g), Cu (247 vs. 116 ug/g), and Co (0.51 vs. 0.27 ug/g) compared with low mineral intake cows, but liver concentrations of Fe, Zn, Mo, and Mn did not differ (P ≥ 0.22). We were able to successfully monitor individual mineral intake and feeding behavior with the electronic feeder evaluated, and the divergence in mineral intake observed with the feeder was corroborated by concentrations of minerals in the liver.

Residual feed intake of Nellore calves is not repeatable across pre and post weaning periods

ABSTRACT: This study measured milk and solid feed intake in pre- weaning period and feed intake in postweaning period of Nellore calves, and to correlated them with performance traits and ingestive behavior of animals classified as most and least efficient. During pre weaning phase, feed efficiency was evaluated in 51 cow-calf pairs from 21±5 days after calving until weaning. During post-weaning phase, only male calves (n=23) were evaluated. Pre-weaning milk intake of calves was estimated based on cow’s milk production. Pre-weaning daily metabolizable energy intake (MEI) of calves was estimated as the sum of MEI from milk and solid diet. There was no difference in ADG between calves with negative and positive pre RFI, with a consequent better feed conversion to more efficient calves. The most efficient calves spent less time at the feed bunk, with a shorter feeding duration and higher rate of intake, compared to the least efficient animals. Correlations between feed intake and metabolic body weight of the animals during pre- and postweaning phases were positive, of medium to high magnitude, and significant, while correlation between ADG values was close to zero. Results suggested that part of the animals ranked based on pre weaning feed intake won’t maintain their rank during postweaning phase. In conclusion, calves classified as most efficient during pre-weaning phase have similar weight gain but lower milk intake and MEI than least efficient animals. The estimated pre RFI is weakly correlated with post RFI, showing that RFI is not consistent or repeatable across two periods.

Declining reproductive success in the Gulf of St. Lawrence's humpback whales (Megaptera novaeangliae) reflects ecosystem shifts on their feeding grounds.

Climate change has resulted in physical and biological changes in the world's oceans. How the effects of these changes are buffered by top predator populations, and therefore how much plasticity lies at the highest trophic levels, are largely unknown. Here endocrine profiling, longitudinal observations of known individuals over 15years between 2004 and 2018, and environmental data are combined to examine how the reproductive success of a top marine predator is being affected by ecosystem change. The Gulf of St. Lawrence, Canada, is a major summer feeding ground for humpback whales (Megaptera novaeangliae) in the North Atlantic. Blubber biopsy samples (n=185) of female humpback whales were used to investigate variation in pregnancy rates through the quantification of progesterone. Annual pregnancy rates showed considerable variability, with no overall change detected over the study. However, a total of 457 photo-identified adult female sightings records with/without calves were collated, and showed that annual calving rates declined significantly. The probability of observing cow-calf pairs was related to favourable environmental conditions in the previous year; measured by herring spawning stock biomass, Calanus spp. abundance, overall copepod abundance and phytoplankton bloom magnitude. Approximately 39% of identified pregnancies were unsuccessful over the 15years, and the average annual pregnancy rate was higher than the average annual calving rate at ~37% and ~23% respectively. Together, these data suggest that the declines in reproductive success could be, at least in part, the result of females being unable to accumulate the energy reserves necessary to maintain pregnancy and/or meet the energetic demands of lactation in years of poorer prey availability rather than solely an inability to become pregnant. The decline in calving rates over a period of major environmental variability may suggest that this population has limited resilience to such ecosystem change.

Short- and long-term effects of temporary early cow–calf separation or restricted suckling on well-being and performance in zebu cattle

Information on weaning techniques in the tropics is scarce, particularly regarding the long-term effect of temporary early cow–calf separation or restricted suckling. Therefore, we studied the effects of these two handling practices on well-being and performance at 150 days postpartum in fifteen zebu cow–calf pairs randomly assigned to three treatments. Continuous suckling (CS) where calves remained with their dams from birth to weaning; restricted suckling (RS) calves were allowed to suckle 30 min/day from Day 34 until weaning at Day 150 and kept separated the rest of the time; temporary separation (TS) calves were separated for 72 h from their dams from Day 33 to 36 but remained with their dams the rest of the time. Blood samples and behavioral data were collected on Days 32–36 (1st period) and 149–153 (2nd period). In the 1st period, a greater percentage of RS and TS calves were observed close to the fence line (<10 m) that separated them from their dams (P < 0.0001) and vocalized more than CS calves (P < 0.0001), while in the 2nd period, RS calves had the highest cortisol concentration and vocalization rate (P < 0.05). Similarly, during the 1st period, a greater percentage of RS and TS cows were observed close to the fence line than CS cows (P < 0.0001), with TS cows vocalizing the most (P = 0.001). In the 2nd period, RS cows had greater cortisol concentration than TS (P = 0.037) and CS cows (P = 0.003). More TS and CS cows than RS were observed close to the fence line (P = 0.03 and P = 0.05). On Day 150, TS calves and cows vocalized more than RS and CS animals (P < 0.0001). Before calf–cow separation, 27 out of 45 cows were cycling (CS = 10; RS = 6; TS = 11). After separation, 12 of the remaining 18 cows resumed ovarian activity (CS = 3; RS = 5; TS = 4), and all cows were cycling after estrous synchronization treatment. The pregnancy rate was similar between CS, RS, and TS (60, 53, and 60% respectively). In conclusion, temporary separation increased calf distress response to definitive weaning even four months later, while restricted suckling seemed to reduce it.

Foraging Behavior of Heritage versus Desert-Adapted Commercial Rangeland Beef Cows in Relation to Dam-Offspring Contact Patterns

We compared cow-calf contacts, as well as movement, activity, and pasture use patterns of heritage Raramuri Criollo (RC) and desert-adapted commercial Angus Hereford crossbred (AH) beef cattle grazing Chihuahuan Desert pastures during 4 wk in the summers of 2016 and 2017. Within each herd of 11 cow-calf pairs, a group of 7−9 randomly selected cows were fitted with Global Positioning System collars that recorded animal position at 10-min intervals. Proximity loggers configured to record contact events (< 1-m radius) were fitted on a subset of five cow-calf pairs of each breed. The effect of breed on cow-calf contacts, as well as the dams’ movement, activity, and pasture use patterns were analyzed via mixed analysis of variance models. A higher number of RC cow-calf contacts occurred while the dam was grazing and traveling compared with AH counterparts (P ≤ 0.05). No breed-related differences were observed in the overall number and duration of cow-calf contact events. Compared with AH dams, RC cows traveled farther each day (RC: 7.51 vs. AH: 4.85 km, P < 0.01) at higher movement velocities (5.46 vs. 3.53 m. min−1, P < 0.01) and spent more time traveling (1.05 vs. 0.48 h, P < 0.01), more time grazing (9.37 vs. 7.45 h, P < 0.01), and less time resting (13.07 vs. 15.68 h, P < 0.01). RC cows explored almost three times more daily area than AH (152.30 vs. 57.69 ha, P = 0.01) but spent similar amounts of time within 200 m and 100 m of a drinker. RC calves explored larger daily areas than their AH counterparts (83.0 vs. 20.8 ha, P = 0.05), but no breed differences were detected in the number of contact events near drinkers. RC calves possibly impose fewer constraints on their dams’ movement and activity patterns compared with commonly used British crossbreds when grazing the Chihuahuan Desert during summer.

38 Effects of combining nose flap weaning with short-term creep feeding of beef calves on cow and calf performance

Abstract One hundred four Angus calves were ranked by gender, BW, age, and dam parity, and assigned to 1 of 4 pre-weaning treatments: 1) nose flaps for 7-d prior to weaning (NF), 2) traditional weaning (TRAD), 3) traditional weaning and creep feed for 3-wk prior to weaning (TRADC), or 4) nose flaps for 7-d prior to weaning and creep feed for 3-wk prior to weaning (NFC). Cow-calf pairs were housed in dry lot pens on d -28. From d -21 to 0, calves in creep treatments were provided free choice access to creep feed. Nose flaps were placed on d -7, and calves were weaned on d 0. Calves were vaccinated and dewormed on d -21 and 0. There was no difference (P ≥ 0.97) in calf BW on d -28 or -21. During the 7-d period that nose flaps were placed, NFC calves had greater (P ≤ 0.0001) ADG than NF and TRAD calves, and tended to have greater (P ≤ 0.10) ADG than TRADC calves. At weaning on d 0, TRADC and NFC calves tended to have greater BW (P = 0.07) and had greater overall change in BW (P &amp;lt; 0.0001) during the pre-weaning period than TRAD and NF calves. Additionally, there was a greater (P ≤ 0.001) increase in BW of NFC and TRADC cows during the pre-weaning period compared to NF and TRAD cows. From d -21 to 0 there was no differences (P &amp;gt; 0.41) in plasma concentrations for Bovine Viral Diarrhea Virus (BVD). By d 14, the TRADC calves had the greatest plasma concentrations for BVD (P &amp;lt; 0.04). Therefore, providing short-term creep feed prior to placing nose flaps can improve pre-weaning calf and cow performance compared to traditional and nose flap weaning without creep feed supplementation, however, did not improve response to vaccination.

100 Young Scholar Presentation: Energy and Mineral Supplementation Strategies for Beef Cattle Grazing the Northern Great Plains

Abstract Three experiments were conducted to evaluate supplementation strategies for beef cattle grazing in the Northern Great Plains. In experiment 1, 28 cow-calf pairs had access to electronic feeders (SmartFeed system; C-Lock Inc., Rapid City, SD) that monitored individual vitamin and mineral supplement (VTM) intake. Cows had greater VTM intakes (81.1 ± 8.2 g/d; P &amp;lt; 0.01) than calves (44.2 ± 8.6 g/d) but both attended feeders a similar (P = 0.71) proportion of days. Furthermore, we noted greater (P &amp;lt; 0.01) concentrations of Se, Cu, and Co in livers of HIGH intake cows compared to LOW intake cows. Experiment 2, we used the SmartFeed system to regulate intake of individual heifers (n = 60) in a group pasture scenario assigned to control (CON), VTM, or energy supplement (NRG) treatments, and evaluated supplement intake, and concentrations of liver mineral and metabolites. Though no differences were observed in BW and ADG, treatments that provided VTM enhanced liver concentrations of Se, Fe, Cu, and Co (P &amp;lt; 0.05). No differences (P = 0.85) were observed in concentrations of NEFA; however, NRG heifers had greater (P = 0.01) glucose concentrations than CON and VTM heifers. Experiment 3 objectives were to determine the influence of feeding VTM and NRG supplements to beef heifers (n = 35) during the first 84 days of pregnancy on concentrations of progesterone (P4), corpus luteum (CL) size and fetal body measurements. Providing NRG during early gestation resulted in heavier CLs (P = 0.003) that produced more P4 (P = 0.002) and greater fetal femur growth (P = 0.009) whereas providing VTM enhanced fetal liver growth (P = 0.05). Overall, we were able to successfully monitor and control individual mineral intake, corroborated those differences in liver mineral concentrations, and observed alterations in fetal growth after mineral and energy supplementation.

PSI-3 Effects of housing cow-calf pairs in drylots vs pasture during the summer on cow performance

Abstract The objective was to evaluate the effects of maintaining cows in drylots vs pasture on beef cow performance. Spring-calving, Simmental × Angus cows (n = 108; 84 ± 11 d postpartum) were stratified by age, BW, BCS, calving date, and sex of calves and allotted to 6 groups. Groups were randomly assigned to 1 of 2 treatments for 110 d: drylot (DL) or pasture (PAST). Drylot cows were limit-fed a ration consisting of corn silage, dried distillers grains, hay, corn stalks, corn, and soybean hulls to meet protein and energy requirements. Cows on pasture were rotationally grazed and offered free-choice mineral. On d 0, cows were artificially inseminated (AI). On d 0, 53, and 110 (weaning), cow BW and BCS were measured. On d 54 milk production was estimated using the weigh-suckle-weigh technique. Data were analyzed using the MIXED procedure of SAS. All binary data were analyzed using the GLIMMIX procedure of SAS. On d 0 and 53, cow BW did not differ (P ≥ 0.73) between DL and PAST. On d 110, DL cows had 74 kg greater (P &amp;lt; 0.01) BW than PAST cows. The BCS did not differ (P ≥ 0.66) between treatments. There was no difference in milk production (P = 0.93); however, drylot cows tended (P = 0.10) to have reduced milk fat percentage and had reduced (P &amp;lt; 0.01) milk urea nitrogen. There was no difference (P ≥ 0.34) in AI or overall pregnancy rates between treatments. There was no difference in foot angle or claw set (P ≥ 0.17) of cows at any time point. There was also no difference (P = 0.17) in foot treatments between DL (39%) and PAST (4%). Housing cows in drylots compared to pasture increased BW, but did not affect BCS, milk production, and pregnancy rates.

102 Impact of weaning strategy on beef cow-calf behavior and activity

Abstract The objective of this study was to investigate the impact of three weaning strategies on cow and calf behavior and activity. Research has shown that weaning imposes stress on both the cow and the calf that can alter behavior, activity, and growth performance. Angus-based cow-calf pairs (n = 147) were randomly assigned to one of three treatment groups, abrupt weaning on d0 (Abrupt, n=50), fence-line contact for 7 days and then relocation of the cow on d7 (Fence, n=50), and late weaning by abrupt separation on d84 (Late, n = 47). Both cow and calf behaviors were observed over 7d prior to weaning and 7d post weaning activity for each treatment group. A single observer recorded activity and vocalizations for each animal twice in morning and evening on observation days. Calf activity was also continuously measured using accelerometers secured to collars worn by five calves per treatment group. Observation and activity data were analyzed using PROC MIXED of SAS. Significance was determined at P &amp;lt; 0.05 and a tendency at 0.05&amp;lt; P ≤0.10. The average activity units per day (AU/d) prior to weaning were similar among treatment groups. On d1 of weaning, Fence calves, who still had a visual contact with their dam, tended to have greater AU/d (P = 0.09) than the Abrupt calves and maintained a higher level of activity through d14 (P &amp;lt; 0.001). Late calves tended to have greater AU/d (P = 0.10) than Abrupt or Fence on d0-1 after their weaning. No difference in vocalizations (P = 0.41) by calves 7d post weaning were observed (1% Abrupt, 0% Fence, and 4% Late). More cows on Fence paced (1%) than Abrupt (0%) or Late (0%) (P &amp;lt; 0.05) in the 7d of fenceline contact. Late cows (2%) vocalized more than Abrupt (1%) or Fence (0%) when their calves were still with them (P &amp;lt; 0.05), but not after (P &amp;gt; 0.05) when no vocalizations were recorded. These results differ from the previous year study; therefore, further investigation of the impact of weaning strategy on cow-calf behavior and activity is warranted.

103 Impact of weaning strategy on beef cow-calf behavior and activity

Abstract The objective of this study was to investigate the impact of three weaning strategies on cow and calf behavior and activity. Research has shown that weaning imposes stress on both the cow and the calf that can alter behavior, activity, and growth performance. Angus-based cow-calf pairs (n = 147) were randomly assigned to one of three treatment groups, abrupt weaning on d0 (Abrupt, n = 50), fence-line contact for 7 days and then relocation of the cow on d7 (Fence, n = 50), and late weaning by abrupt separation on d84 (Late, n = 47). Both cow and calf behaviors were observed over 7d prior to weaning and 7d post weaning activity for each treatment group. A single observer recorded activity and vocalizations for each animal twice in morning and evening on observation days. Calf activity was also continuously measured using accelerometers secured to collars worn by five calves per treatment group. Observation and activity data were analyzed using PROC MIXED of SAS. Significance was determined at P &amp;lt; 0.05 and a tendency at 0.05&amp;lt; P ≤ 0.10. The average activity units per day (AU/d) prior to weaning were similar among treatment groups. On d1 of weaning, Fence calves, who still had a visual contact with their dam, tended to have greater AU/d (P = 0.09) than the Abrupt calves and maintained a higher level of activity through d14 (P &amp;lt; 0.001). Late calves tended to have greater AU/d (P = 0.10) than Abrupt or Fence on d0-1 after their weaning. No difference in vocalizations (P = 0.41) by calves 7d post weaning were observed (1% Abrupt, 0% Fence, and 4% Late). More cows on Fence paced (1%) than Abrupt (0%) or Late (0%) (P &amp;lt; 0.05) in the 7d of fenceline contact. Late cows (2%) vocalized more than Abrupt (1%) or Fence (0%) when their calves were still with them (P &amp;lt; 0.05), but not after (P &amp;gt;0.05) when no vocalizations were recorded. These results differ from the previous year study; therefore, further investigation of the impact of weaning strategy on cow-calf behavior and activity is warranted.

Demographic parameters of southern right whales off South Africa

Aerial counts of right whale cow-calf pairs on the south coast of South Africa between 1971 and 1998 indicate an annual instantaneouspopulation increase rate of 0.068 per year (SE = 0.004) over this period. Annual photographic surveys since 1979 have resulted in 901resightings of 550 individual cows. Observed calving intervals ranged from 2-15 years, with a principal mode at 3 years and secondarymodes at 6, 9 and 12 years, but these make no allowance for missed calvings. Using the model of Payne et al. (1990), a maximum calvinginterval of 5 years produces the best fit to the data giving a mean calving interval of 3.12 years (95% confidence interval: 3.07, 3.17). Thesame model produces an estimate for adult female survival rate of 0.983 (95% CI: 0.972, 0.994). The Payne et al. (1990) model is extendedto incorporate information on the observed ages of first reproduction of grey-blazed calves, which are known to be female. This allows theestimation of age at first parturition (median 7.88 years 95% CI 7.17, 9.29). Updates of estimates and confidence intervals for the otherdemographic parameters are: adult female survival rate 0.986 (0.976, 0.999); first year survival rate 0.913 (0.601, 0.994) and instantaneouspopulation increase rate 0.071 (0.059, 0.082). These biological parameter estimates are shown to be compatible with the observed increaserate of the population without the need to postulate immigration.

Population status and habitat use of southern right whales in the sub-Antarctic Auckland Islands of New Zealand

In the winters of 1995, 1996 and 1997, research was conducted in the Auckland Islands to evaluate the status of southern right whales inthe New Zealand sub-Antarctic. Whales were present in high concentrations each year (maximum count of 146 whales) in a small area onthe northeast side of the main island. Cow-calf pairs averaged 12% (range 9% to 14%) of the total population. Most cow-calf pairs weresighted resting at the surface (60%) or travelling (36%) and showed a strong preference for shallow ( &lt; 20m depth) nearshore waters. Theratio of females to males, as determined by molecular sexing using biopsy samples, varied from 54% to 39% over the three years but didnot differ significantly from 1:1 in any year. Both males and females were found in varying group sizes, with the occurrence of social/sexualactivity predominant (85%) in groups of three or more whales. Most single whales were found resting (59%) and occasionally approachedthe research vessel (19%). A total of 217 individual whales have been photo-identified over the three years of this study, 24% of which wereresighted more than once in a season and approximately 15% of which were resighted in more than one year. The high density of whalesin Port Ross during winter months, the presence of cow-calf pairs, including newborns, and the frequency of social and sexual activityindicates that the Auckland Islands are a primary wintering habitat for southern right whales in New Zealand waters. However, the lowresighting rates within season and documented movement to nearby Campbell Island (290km) suggest that some whales are not residentin the Auckland Islands throughout the season. The rarity of right whales along the main islands of New Zealand and their apparent increasein numbers in the Auckland Islands suggests a major shift in habitat use from pre-exploitation times or the loss of a component of ahistorically sub-divided stock.

Effect of a single subcutaneous injection of meloxicam on chronic indicators of pain and inflammatory responses in 2-month-old knife and band-castrated beef calves housed on pasture

One hundred and thirty-one 2 mo. old pasture housed Angus cross bull calves were evaluated for 62 d over two years (Year 1: n = 69, 134.1 ± 20.37 kg BW; Year 2: n = 62, 118.1 ± 15.49 kg BW) to determine 1) the effects of a subcutaneous (s.c) injection of meloxicam on indicators of long term pain after castration and 2) the potential use of cow-calf proximity and home range as indicators of pain. Calves were randomly assigned to treatments using a 3 × 2 factorial design including castration - sham (CT; n = 47), band (BA; n = 46) or knife (KN; n = 38) castration and medication – s.c. meloxicam (M; n = 66) or s.c. lactated ringers solution (NM; n = 65). Measurements included performance, scrotal temperature, swelling (WS) and healing (WH) scores, and pain sensitivity, collected on d -1, 6, 13, 20, 34, 48, and 62 post-castration. Suckling, lying, standing and walking duration, and head-turning, lesion-licking, foot-stamping and tail-flick frequencies were collected immediately following and up to 2-d after castration. Cow-calf proximity and home range were obtained from d 0 to 2 and from d 14 to 16. With the exception of suckling, no medication (P > 0.05) effects were found. Greater (P < 0.05) pain sensitivity was observed in KN from d 6 to 34 and on d 62, and in BA from d 6 to 62 compared to CT calves. Knife calves showed an earlier (d 20) absence of inflammatory responses (WS; P < 0.05) than BA (d 34) and overall, KN calves had greater (P < 0.05) standing, walking, and head turning than BA and CT. Knife and BA had greater (P < 0.05) foot stamping than CT for the first 2 h post-castration, but KN exhibited greater (P < 0.05) frequencies between 9 and 11 h (d 0) compared to BA and CT, and had greater (P < 0.05) tail flicks from d 0 to 2 than CT. Banded calves were closer to their dams on d 15 while KN calves and their dams had a reduced home range on d 0 than CT cow-calf pairs. Although meloxicam did not reduce indicators of pain (with exception of suckling behavior), our results suggest that knife castration causes greater acute pain, while band castration resulted in greater chronic-pain. Cow-calf proximity and home range have some potential to be used as pain indicators post-castration.

Grain Yield and Beef Cow–Calf Growth Performance in Dual-Purpose and Conventional Grain Wheat Production Systems and Stockpiled Tall Fescue Pasturing

Dualpurpose wheat (Triticum aestivum L) can be used for cattle grazing while producing grain from the same crop. In a two-year study, wheat forage production, grain yield, and growth performance of beef cow–calf pairs grazed on wheat pasture for 2–3 weeks in spring was compared with the conventional wheat grain production system and stockpiled tall fescue (Festuca arundinacea (L.) Schreb) pasturing. Grazing wheat resulted in grain yield (4.1 vs. 4.6 t ha−1) and test weight (65.9 vs. 66.7 kg hL−1) similar to the conventional grain production system. Wheat accumulated significantly lower forage dry matter yield (0.9 vs. 1.9 t ha−1) in spring with higher crude protein (190.2–290.2 vs. 122.0–151.0 g kg−1) and low fiber contents compared to the stockpiled tall fescue pasture. Wheat pasture presented risk for the development of grass tetany with regard to N, K, Na, and Mg contents. Calves grazed on wheat gained 1143–1370 gd−1 body weight compared to the 826–879 gd−1 in the stockpiled tall fescue pasturing. Cows had inconsistent and mixed body weight change response. With warmer temperatures and adequate precipitation controlled grazing of wheat in spring by beef cow–calves offered weight gain benefits exceeding the stockpiled tall fescue pasturing and grain production similar to the conventional wheat grain system.

Influence of Beef Cattle Stocking Density on Utilization of Vegetative Communities in a Late-Spring, Early-Summer Native Bunchgrass Prairie

This study evaluated the influence of cattle stocking density on the use of botanical communities on a native bunchgrass prairie. In each of two years, 192 cow-calf pairs and 48 yearling heifers were randomly selected for the following grazing treatments: 1) control, no livestock grazing; 2) low stocking, 0.36 animal units (AU) ∙ ha-1; 3) moderate stocking, 0.72 AU ∙ ha-1; and 4) high stocking, 1.08 AU ∙ ha-1 for a 42-day grazing period. Thirty-six monitoring sites were established uniformly along a grid in each paddock. Standing crop and relative preference data for cattle collected from the treatment area were used to develop the following vegetation community classifications: 1) &gt; 20% introduced; 2) &gt; 40% native bunchgrass with &gt; 50% Idaho fescue (Festuca idahoensis); 3) &gt; 40% native bunch grass with &lt; 50% Idaho fescue; 4) &gt; 50% Forb; and 5) other. Utilization for each community type was collected at the end of the grazing period. High stocking density paddocks had higher utilization across all vegetation classifications compared to other stocking densities (P ≤ 0.04). Moderate stocking density paddocks were utilized 11.5% more than low paddocks, however, utilization of introduced vegetative communities, Idaho fescue dominated bunchgrass communities, and forb dominated communities did not differ in use (P ≥ 0.13). Use of monitoring to actively adjust stocking densities based on differential community utilization may improve the sustainable grazing of sensitive communities because conventional stocking rate calculations based on total productivity do not account for the selective grazing behavior of cattle.