At weaning, sorting pigs according to body weight is a common practice in the commercial swine production systems. Supposedly, this management practice improves growth performance and reduces body weight variation within batch. The aim of this thesis is to evaluate the effectiveness of a nutritional program in promoting a compensatory growth of light-weight piglets than their heavier-weight counter-parts. The experimental test took place at the husbandry “La Grazia” owned by Loris Scarabello in San Biagio di Callalta (TV). A total of 164 pigs were selected at weaning (28 days) and classified into 2 theses: heavy initial weight (20 pigs per pen) and light initial weight (21 pigs per pen) for a total of 8 pens. For each pen, 10 pigs (5 males and 5 females) were randomly chosen and individually identified by numbered ear tag. From weaning to the next 55 days, the weight of each pen and the individual weights of the 80 subjects were recorded weekly (for a total of 9 samples), while every day the consumption of feed and the type of feed administered was recorded. The husbandry has decided to make changes to the conventional nutritional program with the main purpose of promoting the recovery of piglets with light initial weight by differentiating the diets for the two weight classes and at the same time reducing the amount of feed administered in the last three weeks of housing. From the data collected on the sources of variation of the final weights it is evident that the weaning weight affects the subsequent growth performance in fact all the pigs initial heavy weight has reached final weights equal to or higher than the final average weight. Only 27% of piglets light initial weight manages to recover, recording a final weight around or slightly above average. Heavy initial weight piglets have a higher growth rate and this result mimic previous studies in which heavier piglets at weaning increase their weight advantage in the post weaning. During the test the total variability was reduced from 20% to 14%, overall, it is positive that the variability is reduced and this trend is due to the heavy initial weight piglets that remain uniform and to some light initial weight piglets that manage to recover the initial divergence while increasing the variability within their class. As for the effect of the changes in the feeding plan, the reduction of 30% of the amount of feed administered in the last three weeks is reasonable as the piglets of both classes reach the same weight as predicted. The differentiation of the diets between the two classes also brings benefits: in the first period in which feed changes were the same for both classes, average daily gain of the pigs initial heavy weight was approximately 30% greater while starting from day 30 of housing, in which the piglets heavy initial weight pass to feed 4 while the other class continues with the administration of feed 3, the average daily gains are similar for the two groups. So, the differentiation of the diets supports the growth of lighter piglets even if it is not enough to compensate the initial gap. The results of this thesis suggest that weaning weight is a determining factor for subsequent growth performance and that to promote the recovery of piglets light initial weight the best strategy could be to combine the classification according to weight with nutritional program differentiated according to class.
Allo svezzamento, la formazione di gruppi in base al peso è una pratica gestionale molto utilizzata negli allevamenti suinicoli commerciali. Questa strategia gestionale si suppone migliori le performance di crescita e riduca la variazione di peso tra i suinetti dello stesso lotto. Con la presente tesi di laurea si è voluto analizzare la rilevanza di alcune fonti di variazione del peso dei suinetti al termine della fase di post svezzamento e valutare l’efficacia di una curva alimentare nel favorire il recupero del gruppo di suinetti più leggeri allo svezzamento rispetto a quelli più pesanti. La prova sperimentale si è svolta presso l’azienda agricola La Grazia di Loris Scarabello a San Biagio di Callalta (TV). Per questo caso studio sono stati considerati 164 suini svezzati a 28 giorni di età e classificati in 2 tesi: peso in entrata (PVent) maggiore (20 suini per box) e minore (21 suini per box) per un totale di 8 box. Per ogni box sono stati scelti casualmente 10 soggetti (5 maschi e 5 femmine) ed identificati individualmente tramite marca auricolare numerata. Dallo svezzamento fino all’uscita dall’azienda sono stati rilevati settimanalmente (per un totale di 9 campionamenti) il peso di ogni box ed i pesi individuali degli 80 soggetti scelti mentre ogni giorno è stato registrato il consumo di mangime e la tipologia di mangime somministrato. L’azienda ha deciso di apportare delle modifiche al convenzionale piano alimentare con lo scopo principale di favorire il recupero dei suinetti con PVent minore differenziando le curve alimentari per le due classi di peso e riducendo al tempo stesso la quantità di mangime somministrato nelle ultime tre settimane di stabulazione. Dai dati raccolti relativi alle fonti di variazione dei pesi finali è evidente che il peso allo svezzamento influisce sulle performance di crescita successive infatti tutti i suini peso inziale pesante hanno raggiunto dei pesi finali uguali o superiori al peso medio finale. Solo il 27% dei suinetti PVent minore riesce a recuperare, registrando un peso finale attorno o poco superiore alla media. Durante il corso della prova la variabilità totale si è ridotta passando dal 20% al 14%, complessivamente è positivo che la variabilità si riduca e questo andamento è dovuto ai suinetti PVent maggiore che restano uniformi e ad alcuni suinetti PVent minore che riescono a recuperare la divergenza iniziale aumentando però la variabilità entro la loro classe. Per quanto riguarda invece l’effetto delle modificazioni del piano alimentare risulta ragionevole la riduzione del 30% della quantità di mangime somministrata nelle ultime tre settimane in quanto i suinetti di entrambe le classi raggiungono lo stesso il peso predetto. Anche la differenziazione delle curve alimentari tra le due classi comporta dei benefici: nel primo periodo in cui i cambi di mangime sono stati uguali per entrambe le classi è stato registrato un accrescimento maggiore del 30% per i suinetti peso iniziale pesante mentre a partire dal giorno 30 di stabulazione, in cui i suinetti peso iniziale pesante passano al mangime 4 mentre l’altra classe continua con la somministrazione del mangime 3, gli accrescimenti sono uguali per i due gruppi. Quindi la differenziazione delle due curve alimentari supporta l’accrescimento dei suinetti più leggeri anche se non è sufficiente per compensare la differenza iniziale di peso. I risultati di questa tesi di laurea suggeriscono che il peso allo svezzamento sia un fattore determinate per le performance successive di crescita e che per favorire il recupero dei suinetti peso iniziale leggero la strategia migliore potrebbe essere quella di combinare la classificazione in base al peso con delle curve alimentari differenziate in base alla classe.
Fonti di variazione delle prestazioni di suinetti nel post-svezzamento: risultati di un caso studio in un allevamento specializzato del Veneto
CORRADI, ANTONELLA
2021/2022
Abstract
At weaning, sorting pigs according to body weight is a common practice in the commercial swine production systems. Supposedly, this management practice improves growth performance and reduces body weight variation within batch. The aim of this thesis is to evaluate the effectiveness of a nutritional program in promoting a compensatory growth of light-weight piglets than their heavier-weight counter-parts. The experimental test took place at the husbandry “La Grazia” owned by Loris Scarabello in San Biagio di Callalta (TV). A total of 164 pigs were selected at weaning (28 days) and classified into 2 theses: heavy initial weight (20 pigs per pen) and light initial weight (21 pigs per pen) for a total of 8 pens. For each pen, 10 pigs (5 males and 5 females) were randomly chosen and individually identified by numbered ear tag. From weaning to the next 55 days, the weight of each pen and the individual weights of the 80 subjects were recorded weekly (for a total of 9 samples), while every day the consumption of feed and the type of feed administered was recorded. The husbandry has decided to make changes to the conventional nutritional program with the main purpose of promoting the recovery of piglets with light initial weight by differentiating the diets for the two weight classes and at the same time reducing the amount of feed administered in the last three weeks of housing. From the data collected on the sources of variation of the final weights it is evident that the weaning weight affects the subsequent growth performance in fact all the pigs initial heavy weight has reached final weights equal to or higher than the final average weight. Only 27% of piglets light initial weight manages to recover, recording a final weight around or slightly above average. Heavy initial weight piglets have a higher growth rate and this result mimic previous studies in which heavier piglets at weaning increase their weight advantage in the post weaning. During the test the total variability was reduced from 20% to 14%, overall, it is positive that the variability is reduced and this trend is due to the heavy initial weight piglets that remain uniform and to some light initial weight piglets that manage to recover the initial divergence while increasing the variability within their class. As for the effect of the changes in the feeding plan, the reduction of 30% of the amount of feed administered in the last three weeks is reasonable as the piglets of both classes reach the same weight as predicted. The differentiation of the diets between the two classes also brings benefits: in the first period in which feed changes were the same for both classes, average daily gain of the pigs initial heavy weight was approximately 30% greater while starting from day 30 of housing, in which the piglets heavy initial weight pass to feed 4 while the other class continues with the administration of feed 3, the average daily gains are similar for the two groups. So, the differentiation of the diets supports the growth of lighter piglets even if it is not enough to compensate the initial gap. The results of this thesis suggest that weaning weight is a determining factor for subsequent growth performance and that to promote the recovery of piglets light initial weight the best strategy could be to combine the classification according to weight with nutritional program differentiated according to class.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/36746