The age of surgical castration affects the healing process in beef calves

Castration is painful for calves. Castrating at an earlier age is often recommended, but little is known about how this affects the healing process or the pain experienced. We compared incision closure, swelling and pain sensitivity of beef calves surgically castrated at 3 (range 0 to 8 d; n = 16) or 73 (range 69 to 80 d; n = 15) d of age. Closure of the incision, as measured with a 5-point scale (1 = fresh wound, 5 = no longer visible), weight gain, and inflammation (skin temperature and swelling, as measured by scrotal circumference) were recorded on d 1, 3, 7, 11, 15, 18, 21, 25, 32, 39, 45, 61, and 77 after the procedure, until all incisions were fully healed. On these same days, pain sensitivity was assessed by applying a known and increasing force with von Frey hairs (0.02 to 300 g-force) at the edge of the castration wound and at a control site, approximately 2 to 5 cm anterior to the teats, until animals showed a behavioral response or the highest force was reached. The incisions of younger calves healed more quickly than older ones [fully healed, median (95% confidence interval); 39 (32 to 61) vs. 61 (61 to 77) d; P = 0.002], however, they had relatively more swelling in the days after castration (P < 0.001). Younger animals reacted to lighter pressure of von Frey hairs compared to older calves especially in the first stages of healing process (P < 0.001), and there were other signs indicative of inflammation processes in this region at this time. However, there was no difference in the control site for either age group. In addition, it took longer for older calves to recover their daily weight gain after the procedure (P < 0.001). Taken together, these results paint a mixed picture about the effects of age of surgical castration. Calves castrated soon after birth experience more tissue swelling and show more signs of pain, but their incisions heal sooner and their weight gain is less affected, when compared to animals castrated around 73 d of age.Peer reviewe

The age of surgical castration affects the healing process in beef calves

Castration is painful for calves. Castrating at an earlier age is often recommended, but little is known about how this affects the healing process or the pain experienced. We compared incision closure, swelling and pain sensitivity of beef calves surgically castrated at 3 (range 0 to 8 d; n = 16) or 73 (range 69 to 80 d; n = 15) d of age. Closure of the incision, as measured with a 5-point scale (1 = fresh wound, 5 = no longer visible), weight gain, and inflammation (skin temperature and swelling, as measured by scrotal circumference) were recorded on d 1, 3, 7, 11, 15, 18, 21, 25, 32, 39, 45, 61, and 77 after the procedure, until all incisions were fully healed. On these same days, pain sensitivity was assessed by applying a known and increasing force with von Frey hairs (0.02 to 300 g-force) at the edge of the castration wound and at a control site, approximately 2 to 5 cm anterior to the teats, until animals showed a behavioral response or the highest force was reached. The incisions of younger calves healed more quickly than older ones [fully healed, median (95% confidence interval); 39 (32 to 61) vs. 61 (61 to 77) d; P = 0.002], however, they had relatively more swelling in the days after castration (P &lt; 0.001). Younger animals reacted to lighter pressure of von Frey hairs compared to older calves especially in the first stages of healing process (P &lt; 0.001), and there were other signs indicative of inflammation processes in this region at this time. However, there was no difference in the control site for either age group. In addition, it took longer for older calves to recover their daily weight gain after the procedure (P &lt; 0.001). Taken together, these results paint a mixed picture about the effects of age of surgical castration. Calves castrated soon after birth experience more tissue swelling and show more signs of pain, but their incisions heal sooner and their weight gain is less affected, when compared to animals castrated around 73 d of age

Domestic cattle (Bos taurus taurus) are motivated to obtain forage and demonstrate contrafreeloading

Domestic cattle (Bos taurus taurus) are adapted to digest high-roughage diets, but in confinement they are commonly fed low-roughage, high-energy diets. This practice may leave cattle with an unfulfilled need to consume forage. A way to quantify motivation is to require animals to work to access a resource. Using this method, we evaluated cattle motivation to obtain forage when fed high- or low-roughage diets during and 30 d before the study. Individual heifers were fed Sudan grass (Sorghum × drummondii) hay (high roughage, n = 6) or a diet with 12% forage (as fed, low roughage, n = 6) in an open feed trough. In a second trough, 200 g/d of Sudan grass hay were fed behind a push gate, to which additional weight was added daily until heifers no longer pushed. We predicted heifers would push heavier weights, show a shorter latency, and spend more time pushing the gate when fed a low- vs. high-roughage diet. Indeed, heifers fed a low-roughage diet pushed the gate immediately after hay delivery (1.7 min) and much sooner than those fed a high-roughage diet (75.7 min). On the day before they no longer pushed the gate, latency for heifers in the low-roughage treatment remained only 3.2 min after hay delivery. The suddenness with which they ceased pushing the next day suggests they were unable to move heavier weights to express their motivation. This may explain why maximum weight pushed and time spent pushing the gate did not differ between treatments. The gate pushing by heifers with unrestricted hay access is the first demonstration by cattle of contrafreeloading: performing work to obtain a resource that is simultaneously available for free. In conclusion, consuming forage is important to cattle and is affected by both their primary diet and an internal motivation to work to obtain feed

Trough with weighted gate heifers had to push to access hay.

<p>The main photo is an overhead view of the outside of the gated trough, and the inset shows the gate from inside the pen. The gate had 2 bars (A) to which weight plates were added. A black line (B) was painted on the wall to mark the position of the gate when fully closed.</p

Domestic cattle (<i>Bos taurus taurus</i>) are motivated to obtain forage and demonstrate contrafreeloading

<div><p>Domestic cattle (<i>Bos taurus taurus</i>) are adapted to digest high-roughage diets, but in confinement they are commonly fed low-roughage, high-energy diets. This practice may leave cattle with an unfulfilled need to consume forage. A way to quantify motivation is to require animals to work to access a resource. Using this method, we evaluated cattle motivation to obtain forage when fed high- or low-roughage diets during and 30 d before the study. Individual heifers were fed Sudan grass (<i>Sorghum × drummondii</i>) hay (high roughage, <i>n =</i> 6) or a diet with 12% forage (as fed, low roughage, <i>n</i> = 6) in an open feed trough. In a second trough, 200 g/d of Sudan grass hay were fed behind a push gate, to which additional weight was added daily until heifers no longer pushed. We predicted heifers would push heavier weights, show a shorter latency, and spend more time pushing the gate when fed a low- vs. high-roughage diet. Indeed, heifers fed a low-roughage diet pushed the gate immediately after hay delivery (1.7 min) and much sooner than those fed a high-roughage diet (75.7 min). On the day before they no longer pushed the gate, latency for heifers in the low-roughage treatment remained only 3.2 min after hay delivery. The suddenness with which they ceased pushing the next day suggests they were unable to move heavier weights to express their motivation. This may explain why maximum weight pushed and time spent pushing the gate did not differ between treatments. The gate pushing by heifers with unrestricted hay access is the first demonstration by cattle of contrafreeloading: performing work to obtain a resource that is simultaneously available for free. In conclusion, consuming forage is important to cattle and is affected by both their primary diet and an internal motivation to work to obtain feed.</p></div

Latency and time spent using each trough.

<p>Back-transformed means and 95% confidence intervals are shown for the latency to use the (A) gated and (B) open trough after the 0800 h feed delivery and means ± SEM for the total time heifers spent using the (C) gated and (D) open trough. All heifers were fed 200 g/d of Sudan grass hay behind a gate that must be pushed to gain access, and to which additional weight was added daily until cattle no longer used it. In the unrestricted open trough, heifers had free access to either a total mixed ration with 12% forage (as fed, low roughage, <i>n =</i> 6) or 100% Sudan grass hay (high roughage, <i>n =</i> 6). To allow for consistent comparisons among heifers, behavior was evaluated on 5 d (relative to the day they pushed the maximum weight), and data are presented across days. Day was included in the model as a continuous variable, but was summarized as categorical for graphing purposes.</p

Feed intake and feeding rate from each trough.

<p>Means ± SEM are shown for intake of (A) Sudan grass hay from the gated trough and (B) the primary diet treatments from the open trough, (C) back-transformed means and 95% confidence intervals for the feeding rate from the gated trough, and (D) means ± SEM for the feeding rate from the open trough. All heifers were fed 200 g/d of Sudan grass hay behind a gate that must be pushed to gain access, and to which additional weight was added daily until cattle no longer used it. In the unrestricted open trough, heifers had free access to either a total mixed ration with 12% forage (as fed, low roughage, <i>n =</i> 6) or 100% Sudan grass hay (high roughage, <i>n =</i> 6). To allow for consistent comparisons among heifers, behavior was evaluated on 5 d (relative to the day they pushed the maximum weight), and data are presented across days. Day was included in the model as a continuous variable but was summarized as categorical for graphing purposes.</p

Descriptive data for diurnal patterns of trough use.

<p>The mean ± SEM amounts of time heifers spent using the (A) gated or (B) open feed trough are shown by hour of the day. At 0800 h, all heifers were fed Sudan grass hay behind a weighted gate that must be pushed open to gain access. The primary diet treatments were delivered to the open trough at 0800 and 1400 h, and consisted of either a total mixed ration with 12% forage (as fed, low roughage, <i>n =</i> 6) or 100% Sudan grass hay (high roughage, <i>n =</i> 6).</p

Ingredients, chemical analysis, and calculated energy for the primary diets.

<p>Ingredients, chemical analysis, and calculated energy for the primary diets.</p