fix - improve response time of org linked ranchers

apps/livestock/models.py

@@ -1,7 +1,8 @@
+from django.db import models
+
 from apps.core.models import BaseModel
 from apps.herd import models as herd_models
 from apps.tag import models as tag_models
-from django.db import models
 
 
 class LiveStockSpecies(BaseModel):  # noqa
@@ -53,6 +54,7 @@ class LiveStock(BaseModel):
         herd_models.Herd,
         on_delete=models.CASCADE,
         related_name="live_stock_herd",
+        db_index=True,
         null=True
     )
     tag = models.ForeignKey(
@@ -113,9 +115,9 @@ class TemporaryLiveStock(BaseModel):
         null=True
     )
     count = models.PositiveBigIntegerField(default=0)
-    
+
     def __str__(self):
         return f'temporary: {self.id} - rancher: {self.rancher.national_code}'
-    
+
     def save(self, *args, **kwargs):
         return super(TemporaryLiveStock, self).save(*args, **kwargs)